PB00-910401 ‘I

NATIONAL

TRANSPORTATION

SAFETY

BOARD

WASHINGTON, D.C. 20594

AIRCRAFT ACCIDENT REPORT

CONTROLLED FLIGHT INTO TERRAIN

KOREAN AIR FLIGHT 801

BOEING 747-300, HL7468

NIMITZ HILL, GUAM

AUGUST 6, 1997

NTSB/AAR-00/01

DCA97MA058

6952B
National Transportation Safety Board. 2000. Controlled Flight Into Terrain, Korean Air Flight 801, Boeing

747-300, HL7468, Nimitz Hill, Guam, August 6, 1997. Aircraft Accident Report NTSB/AAR-00/01.

Washington, DC.

Abstract: This report explains the accident involving Korean Air flight 801, a Boeing 747-300, which

crashed into high terrain at Nimitz Hill, Guam, on August 6, 1997. Safety issues in the report focus on

flight crew performance, approach procedures, and pilot training; air traffic control, including controller

performance and the inhibition of the minimum safe altitude warning system at Guam; emergency

response; the adequacy of Korean Civil Aviation Bureau and Federal Aviation Administration oversight;

and flight data recorder documentation. Safety recommendations concerning these issues are addressed to

the Federal Aviation Administration, the Governor of the Territory of Guam, and the Korean Civil

Aviation Bureau.

The National Transportation Safety Board is an independent Federal agency dedicated to promoting aviation, raiload,

highway, marine, pipeline, and hazardous materials safety. Established in 1967, the agency is mandated by Congress

through the Independent Safety Board Act of 1974 to investigate transportation accidents, study transportation safety

issues, and evaluate the safety effectiveness of government agencies involved in transportation. The Safety Board

makes public its actions and decisions through accident reports, safety studies, special investigation reports, safety

recommendations, and statistical reviews.

Recent publications are available in their entirety at <http://www.ntsb.gov>. Other information about available

publications may also be obtained from the Web site or by contacting:

National Transportation Safety Board

Public Inquiries Section, RE-51

490 L’Enfant Plaza, East, S.W.

Washington, D.C. 20594

(800) 877-6799 or (202) 314-6551

Safety Board publications may be purchased, by individual copy or by subscription, from the National Technical

Information Service. To purchase this publication, order report number PB00-910401 from:

National Technical Information Service

5285 Port Royal Road

Springfield, Virginia 22161

(800) 553-6847 or (703) 605-6000
Aircraft Accident Report

Controlled Flight Into Terrain

Korean Air Flight 801

Boeing 747-300, HL7468

Nimitz Hill, Guam

August 6, 1997

NTSB/AAR-00/01

PB00-910401 National Transportation Safety Board

Notation 6952B 490 L’Enfant Plaza, S.W.

Adopted January 13, 2000 Washington, D.C. 20594

iii Aircraft Accident Report

Contents

Abbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

1. Factual Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 History of Flight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Injuries to Persons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.3 Damage to Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.4 Other Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.5 Personnel Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.5.1 The Captain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.5.2 The First Officer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.5.3 The Flight Engineer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.5.4 The Flight Attendants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.5.5 The Air Traffic Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.5.5.1 Combined Center/Radar Approach Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.5.5.2 Air Traffic Control Tower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1.6 Airplane Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.6.1 Maintenance Discrepancies Before the Accident Flight . . . . . . . . . . . . . . . . . . . . . 14

1.6.2 Cockpit Instrumentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.6.2.1 Autopilot System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.6.2.2 Ground Proximity Warning System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

1.6.2.3 Instrument Landing System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

1.6.3 Weight and Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

1.7 Meteorological Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

1.7.1 Weather Conditions at Guam International Airport. . . . . . . . . . . . . . . . . . . . . . . . . 20

1.7.2 Air Traffic Control Weather Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1.7.3 Additional Weather Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

1.8 Aids to Navigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

1.9 Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

1.10 Airport Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

1.10.1 Air Traffic Control Services for Guam International Airport . . . . . . . . . . . . . . . . . 25

1.10.1.1 Combined Center/Radar Approach Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

1.10.1.2 Minimum Safe Altitude Warning System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

1.10.1.3 Air Traffic Control Tower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

1.10.2 Instrument Landing System Ground-Based Equipment. . . . . . . . . . . . . . . . . . . . . . 31

1.10.3 Instrument Approach Procedures at Guam International Airport . . . . . . . . . . . . . . 32

1.10.3.1 The Nonprecision Runway 6L Instrument Landing System 

Localizer-only (Glideslope Out) Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

1.10.3.2 Instrument Approach Charts for Guam International Airport . . . . . . . . . . . . . . . 33

1.11 Flight Recorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

1.11.1 Flight Data Recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

1.11.2 Cockpit Voice Recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Contents iv Aircraft Accident Report

1.12 Wreckage and Impact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

1.12.1 General Wreckage Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

1.12.2 Fuselage and Empennage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

1.12.3 Wings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

1.12.4 Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

1.13 Medical and Pathological Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

1.14 Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

1.15 Survival Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

1.15.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

1.15.2 Survivor Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

1.15.3 Emergency Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

1.15.3.1 Emergency Response Planning and Exercises. . . . . . . . . . . . . . . . . . . . . . . . . . . 48

1.15.4 Guam Governor’s Accident Response Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

1.16 Tests and Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

1.16.1 Enhanced Ground Proximity Warning System Simulation . . . . . . . . . . . . . . . . . . . 49

1.16.2 Minimum Safe Altitude Warning System Simulation . . . . . . . . . . . . . . . . . . . . . . . 50

1.16.3 Korean Air Spurious Radio Signal Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

1.16.3.1 Guam Instrument Landing System and Potential Interference 

From Spurious Radio Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

1.17 Organizational and Management Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

1.17.1 Korean Air Postaccident Safety Initiatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

1.17.2 Korean Air Flight Crew Training. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

1.17.2.1 Basic and Advanced Instrument Flight Course . . . . . . . . . . . . . . . . . . . . . . . . . . 56

1.17.2.2 Boeing 747 Flight Crew Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

1.17.2.3 Crew Resource Management Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

1.17.2.4 Postaccident Changes to Flight Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

1.17.3 Korean Air Preflight Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

1.17.3.1 Supervisor of Flying Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

1.17.3.2 Airport Familiarization Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

1.17.4 Korean Air Descent and Approach Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

1.17.4.1 Briefing and Checklist Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

1.17.4.2 Flight Crew Actions and Callouts During Nonprecision Approaches. . . . . . . . . 64

1.17.4.3 Terrain Avoidance Recovery Maneuvers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

1.17.5 Korean Air Accident and Incident History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

1.17.5.1 1983 to 1997 Accident History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

1.17.5.2 1998 and 1999 Accident and Incident History . . . . . . . . . . . . . . . . . . . . . . . . . . 71

1.17.6 Oversight of Korean Air. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

1.17.6.1 Korean Civil Aviation Bureau . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

1.17.6.1.1 Accident and Incident Investigation Authority . . . . . . . . . . . . . . . . . . . . . . . 73

1.17.6.2 Federal Aviation Administration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

1.17.6.2.1 International Aviation Safety Assessment Program . . . . . . . . . . . . . . . . . . . 75

1.17.6.3 Department of Transportation Audit Report on Aviation Safety 

Under International Code Share Agreements . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

1.18 Additional Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

1.18.1 Minimum Safe Altitude Warning System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

1.18.1.1 Postaccident Actions Taken by the Federal Aviation Administration. . . . . . . . . 81

1.18.1.2 Previous Safety Board Recommendations on the 

Minimum Safe Altitude Warning System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

1.18.2 Traditional and Enhanced Ground Proximity Warning Systems . . . . . . . . . . . . . . . 93

1.18.2.1 Traditional Ground Proximity Warning System . . . . . . . . . . . . . . . . . . . . . . . . . 93
Contents v Aircraft Accident Report

1.18.2.2 Enhanced Ground Proximity Warning System . . . . . . . . . . . . . . . . . . . . . . . . . . 94

1.18.2.2.1 Notice of Proposed Rulemaking for Enhanced Ground 

Proximity Warning Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

1.18.2.3 Department of Transportation Studies on Traditional and 

Enhanced Ground Proximity Warning Systems . . . . . . . . . . . . . . . . . . . . . . . . . 95

1.18.2.4 Previous Safety Board Recommendations on Traditional and 

Enhanced Ground Proximity Warning Systems . . . . . . . . . . . . . . . . . . . . . . . . . 96

1.18.3 Controlled Flight Into Terrain Accident Information . . . . . . . . . . . . . . . . . . . . . . 103

1.18.3.1 Flight Safety Foundation Study of 

Controlled Flight Into Terrain Accidents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

1.18.3.2 Factors Involved in Recent Controlled Flight 

Into Terrain Accidents and Incidents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

1.18.3.3 Controlled Flight Into Terrain Training Aids . . . . . . . . . . . . . . . . . . . . . . . . . . 107

1.18.3.4 Previous Safety Board Recommendations Related to 

Controlled Flight Into Terrain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

1.18.3.5 Previous Controlled Flight Into Terrain Accidents Related to 

Nonprecision Instrument Approach Procedures . . . . . . . . . . . . . . . . . . . . . . . . 113

1.18.4 Industry Actions to Improve the Safety of Nonprecision 

Instrument Approaches Conducted by Air Carriers. . . . . . . . . . . . . . . . . . . . . . . . 114

1.18.4.1 Nonprecision Approach Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

1.18.4.2 Approach Chart Terrain Depiction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

1.18.4.3 Federal Aviation Administration Form 8260. . . . . . . . . . . . . . . . . . . . . . . . . . . 116

1.18.4.4 Previous Safety Board Recommendations Related to 

Approach Procedure Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

1.18.5 Flight Crew Decision-making . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

1.18.5.1 Safety Board Study of Flight Crew Involvement in Major Accidents. . . . . . . . 120

1.18.5.2 Previous Safety Recommendations on Flight Crew Decision-making . . . . . . . 122

1.18.5.3 National Aeronautics and Space Administration’s 

Flight Crew Decision-making Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

1.18.6 Previous Fatigue-Related Accidents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

1.18.6.1 Previous Safety Recommendations Regarding Fatigue. . . . . . . . . . . . . . . . . . . 128

1.18.7 Flight Data Recorder Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

1.18.7.1 Previous Safety Board Recommendations on Flight Data Recorder 

Parameter Verification and Documentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

1.18.7.1.1 Digital Flight Data Recorder Advisory Circular . . . . . . . . . . . . . . . . . . . . . 132

1.18.7.2 International Guidance Regarding the Documentation of 

Flight Data Recorder Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

1.18.8 Special Airport Criteria and Designation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

2. Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

2.2 Weather Factors on the Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

2.3 Accident Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

2.3.1 Description of the Approach and Required Flight Crew Procedures. . . . . . . . . . . 136

2.3.2 Flight 801’s Premature Descent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

2.4 Flight Crew Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

2.4.1 The Captain’s Performance of the Approach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

2.4.1.1 Approach Briefing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Contents vi Aircraft Accident Report

2.4.1.2 Expectation of a Visual Approach and Role of the Guam 

Airport Familiarization Video . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

2.4.1.3 Possible Explanations for the Approach Conducted . . . . . . . . . . . . . . . . . . . . . 142

2.4.1.3.1 Confusion About Status of Glideslope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142

2.4.1.3.2 Confusion About Location of DME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

2.4.1.4 Summary of Captain’s Performance on the Approach . . . . . . . . . . . . . . . . . . . 145

2.4.2 Flight Crew Monitoring of the Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

2.4.3 Flight Crew Fatigue Factors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

2.5 Pilot Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

2.6 Air Traffic Control Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

2.6.1 Controller Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

2.6.2 Intentional Inhibition of the Minimum Safe Altitude 

Warning System at Guam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

2.7 Emergency Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

2.8 Controlled Flight Into Terrain. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

2.8.1 Constant Angle of Descent Nonprecision Approaches . . . . . . . . . . . . . . . . . . . . . 161

2.8.2 Safety Aspects of Enhanced Ground Proximity Warning Systems . . . . . . . . . . . . 162

2.8.3 Terrain Depiction on Approach Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

2.8.4 User Review of Instrument Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

2.9 Oversight Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

2.9.1 Korean Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

2.9.2 Korean Civil Aviation Bureau Oversight of Korean Air . . . . . . . . . . . . . . . . . . . . 166

2.9.3 Federal Aviation Administration Oversight of Korean Air 

and Assessment of Korean Civil Aviation Bureau. . . . . . . . . . . . . . . . . . . . . . . . . 167

2.9.3.1 Independent Accident Investigation Authority . . . . . . . . . . . . . . . . . . . . . . . . . 169

2.10 Flight Data Recorder Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

3. Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

3.1 Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

3.2 Probable Cause . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

4. Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

5. Appendixes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179

A: Investigation and Hearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179

B: Cockpit Voice Recorder Transcript . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180

C: Flight Safety Foundation Study Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
Contents vii Aircraft Accident Report

Figures

1. Instrument approach chart for the Guam International Airport 

runway 6L ILS procedure.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2. Side view of FAA radar data with selected ATC 

and CVR communication excerpts.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3. Overhead view of FAA radar data with selected ATC 

and CVR communication excerpts.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4. Captain’s instrumentation panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

5. First officer’s instrumentation panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

6. WSR-88D four-panel base reflectivity product for Guam. . . . . . . . . . . . . . . . . . . . . . . . . . . 22

7. The January 19, 1996, 11-1 ILS runway 6L instrument approach chart. . . . . . . . . . . . . . . . 35

8a. Wreckage from Korean Air flight 801 in relation to 

Guam International Airport runway 6L, the NIMITZ VOR, and Apra Harbor. . . . . . . . . . . 38

8b. Closer view of the wreckage from Korean Air flight 801 and the NIMITZ VOR.. . . . . . . . 39

9. Korean Air flight 801 cabin configuration and survivor seat locations. . . . . . . . . . . . . . . . . 44

10. Vertical profile information from the 40 CFIT accidents 

and incidents between 1986 and 1990. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

Tables

1. Injury chart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2. Information differences between the January 19 and August 2, 1996, 

Guam ILS runway 6L approach charts.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

3. Loss totals and rates for the 10-year period ending December 31, 1998, 

by losses per 1 million departures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

4. Distribution of errors identified in the 37 accidents reviewed 

in the Safety Board’s 1994 safety study. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
viii Aircraft Accident Report

Abbreviations

AC advisory circular

ADF automatic direction finder

ADI attitude director indicator

AFB Air Force Base

agl above ground level 

AIG Accident Investigation Group

ALA approach and landing accident

ALPA Air Line Pilots Association

ARFF aircraft rescue and firefighting

ARTS Automated Radar Terminal System

ASR Airport Surveillance Radar

ATC air traffic control

ATCT air traffic control tower

ATIS automatic terminal information service

ATP airline transport pilot

CAA civil aviation authority

CAMI Civil Aeromedical Institute

CDI course deviation indicator

CERAP Combined Center/Radar Approach Control

CFIT controlled flight into terrain

CFR Code of Federal Regulations

CRM crew resource management

CVR cockpit voice recorder

D-BRITE digital bright radar indicator tower equipment

DFDR digital flight data recorder

DH decision height

DME distance measuring equipment

DOD Department of Defense

DOT Department of Transportation

DOT/IG Department of Transportation Office of Inspector General

EARTS En route Automated Radar Tracking System

EMT emergency management technician

EU European Union

FAA Federal Aviation Administration

FAF final approach fix

FAR Federal Aviation Regulation

FD flight director

FDAU flight data acquisition unit

FDR flight data recorder

F/E flight engineer

FMA flight mode annunciator
Abbreviations ix Aircraft Accident Report

FMS flight management system

FSF Flight Safety Foundation

GCD Guam Civil Defense

GFD Guam Fire Department

GPS global positioning system

GPWS ground proximity warning system

GS glideslope

HAT height above touchdown

Hg Mercury

HSI horizontal situation indicator

Hz Hertz

IAF initial approach fix

IASA International Aviation Safety Assessment

ICAO International Civil Aviation Organization

IFR instrument flight rules

ILS instrument landing system

IMC instrument meteorological conditions

IOE initial operational experience

KCAB Korean Civil Aviation Bureau

kg kilogram

LOC localizer

LOFT line-oriented flight training

MAP missed approach point

MDA minimum descent altitude

MHz megahertz

MOCT Ministry of Construction and Transport

MOU memorandum of understanding

MSAW minimum safe altitude warning

msl mean sea level

NASA National Aeronautics and Space Administration

NDB nondirectional beacon

nm nautical mile

NOTAM Notice to Airmen

NPRM notice of proposed rulemaking

NWS National Weather Service

OSC on-scene commander

OST Office of the Secretary of Transportation

PAPI precision approach path indicator

PF pilot flying

PIC pilot-in-command

PNF pilot not flying

POI principal operations inspector
Abbreviations x Aircraft Accident Report

SIGMET Significant Meteorological Information 

SOF supervisor of flying

SOP standard operating procedure

STAR standard terminal arrivals 

STARS Standard Terminal Automation Replacement System

TACAN tactical air control and navigation

TAESA Transportes Aereos Ejecutivos, S.A.

TAF terminal aerodrome forecast

TAWS terrain awareness and warning system

TCAS traffic alert and collision avoidance system

TERPS Terminal Instrument Procedures

TOD top of descent

TRACON terminal radar approach control

TSA time since awakening

TSO technical standard order

UTC coordinated universal time

VASI visual approach slope indicator

VFR visual flight rules

VHF very high frequency

VMC visual meteorological conditions

VNAV vertical navigation

VOR very high frequency omnidirectional radio range

WSR-88D Weather Surveillance Radar-1988, Doppler
xi Aircraft Accident Report

Executive Summary

On August 6, 1997, about 0142:26 Guam local time, Korean Air flight 801, a

Boeing 747-3B5B (747-300), Korean registration HL7468, operated by Korean Air

Company, Ltd., crashed at Nimitz Hill, Guam. Flight 801 departed from Kimpo

International Airport, Seoul, Korea, with 2 pilots, 1 flight engineer, 14 flight attendants,

and 237 passengers on board. The airplane had been cleared to land on runway 6 Left at

A.B. Won Guam International Airport, Agana, Guam, and crashed into high terrain about

3 miles southwest of the airport. Of the 254 persons on board, 228 were killed, and

23 passengers and 3 flight attendants survived the accident with serious injuries. The

airplane was destroyed by impact forces and a postcrash fire. Flight 801 was operating in

U.S. airspace as a regularly scheduled international passenger service flight under the

Convention on International Civil Aviation and the provisions of 14 Code of Federal

Regulations Part 129 and was on an instrument flight rules flight plan.

The National Transportation Safety Board determines that the probable cause of

the Korean Air flight 801 accident was the captain’s failure to adequately brief and

execute the nonprecision approach and the first officer’s and flight engineer’s failure to

effectively monitor and cross-check the captain’s execution of the approach. Contributing

to these failures were the captain’s fatigue and Korean Air’s inadequate flight crew

training. Contributing to the accident was the Federal Aviation Administration’s (FAA)

intentional inhibition of the minimum safe altitude warning system (MSAW) at Guam and

the agency’s failure to adequately manage the system.

The safety issues in this report focus on flight crew performance, approach

procedures, and pilot training; air traffic control, including controller performance and the

intentional inhibition of the MSAW system at Guam; emergency response; the adequacy

of Korean Civil Aviation Bureau (KCAB) and FAA oversight; and flight data recorder

documentation. Safety recommendations concerning these issues are addressed to the

FAA, the Governor of the Territory of Guam, and the KCAB.

1 Aircraft Accident Report

1. Factual Information

1.1 History of Flight

On August 6, 1997, about 0142:26 Guam local time,1 Korean Air flight 801, a

Boeing 747-3B5B (747-300), Korean registration HL7468, operated by Korean Air

Company, Ltd., crashed at Nimitz Hill, Guam.2 Flight 801 departed from Kimpo

International Airport, Seoul, Korea, with 2 pilots, 1 flight engineer, 14 flight attendants,

and 237 passengers3

 on board. The airplane had been cleared to land on runway 6 Left at

A.B. Won Guam International Airport, Agana, Guam, and crashed into high terrain about

3 miles southwest of the airport. Of the 254 persons on board, 228 were killed,4 and

23 passengers and 3 flight attendants survived the accident with serious injuries.5 The

airplane was destroyed by impact forces and a postcrash fire. Flight 801 was operating in

U.S. airspace as a regularly scheduled international passenger service flight under the

Convention on International Civil Aviation and the provisions of 14 Code of Federal

Regulations (CFR) Part 129 and was on an instrument flight rules (IFR) flight plan.

According to Korean Air company records, the flight crew arrived at the dispatch

center in the Korean Air headquarters building in Seoul about 2 hours before the scheduled

departure time of 2105 (2005 Seoul local time) on August 5, 1997. The original flight plan for

flight 801 listed a different captain’s name. The captain aboard the accident flight had initially

been scheduled to fly to Dubai, United Arab Emirates; however, because the accident captain

did not have adequate rest for that trip, he was reassigned the shorter trip to Guam.6

According to Korean Air personnel, the flight crewmembers collected the trip

paperwork, conducted a self-briefing, and received a briefing from the assigned supervisor

of flying (SOF).7 Flight 801 departed the gate about 2127 and was airborne about 2153.

1 Unless otherwise indicated, all times are Guam local time, based on a 24-hour clock. 

2 The island of Guam is a U.S. territory in the Pacific Ocean and is part of the Mariana Islands. Guam

has an elected governor and a 21-member unicameral legislature. U.S. Naval and Air Force installations

make up 35 percent of the island’s area. 

3 Six of the passengers were Korean Air flight attendants who were “deadheading,” that is, traveling off

duty.

4 Three passengers (including one deadheading flight attendant) initially survived the accident with

serious injuries but died within 30 days after the accident. According to 14 Code of Federal Regulations

(CFR) Section 830.2, such fatalities are to be included in the total number of fatal injuries. A passenger with

serious injuries died at the U.S. Army Medical Center in San Antonio, Texas, on October 10, 1997, but is not

officially listed as a fatality because the passenger’s death occurred more than 30 days after the accident.

5 See table 1 in section 1.2 for the injury chart.

6 The captain began a scheduled round trip to Hong Kong on August 3, 1997, but his return flight was

delayed because of inclement weather. As a result, the captain had to remain overnight in Hong Kong and fly

back to Seoul (as a pilot) on the morning of August 4. 

7 The self- and SOF briefings are required parts of Korean Air’s flight crew predeparture procedures.

See section 1.17.3 for additional information.
Factual Information 2 Aircraft Accident Report

According to the cockpit voice recorder (CVR), the captain was performing the pilotflying (PF) duties, and the first officer was performing the pilot-not-flying (PNF) duties.

Upon arrival to the Guam area, the first officer made initial contact with the Federal

Aviation Administration’s (FAA) Guam Combined Center/Radar Approach Control

(CERAP) controller about 0103:18, when the airplane was level at 41,000 feet mean sea

level (msl) and about 240 nautical miles (nm) northwest of the NIMITZ VOR/DME.8

About 0105:00, the CERAP controller told flight 801 to expect to land on runway 6L,

and the first officer acknowledged the transmission. About 0110:00, the controller instructed

flight 801 to “...descend at your discretion maintain two thousand six hundred [feet msl].”

The first officer responded, “...descend two thousand six hundred pilot discretion.” 

About 0111:51, the CVR9

 recorded the captain briefing the first officer and the

flight engineer about the approach and landing at Guam. The captain stated: 

I will give you a short briefing...ILS [instrument landing system10] is one one

zero three...NIMITZ VOR is one one five three, the course zero six three, since

the visibility is six, when we are in the visual approach, as I said before, set the

VOR on number two and maintain the VOR for the TOD [top of descent],11 I will

add three miles from the VOR, and start descent when we’re about one hundred

fifty five miles out. I will add some more speed above the target speed. Well,

everything else is all right. In case of go-around, since it is VFR [visual flight

rules], while staying visual and turning to the right...request a radar vector...if

not, we have to go to FLAKE12...since the localizer glideslope is out,13 MDA

[minimum descent altitude] is five hundred sixty feet and HAT [height above

touchdown] is three hundred four feet....

About 0113:33, the CVR recorded the captain saying, “we better start descent;”

shortly thereafter, the first officer advised the controller that flight 801 was “leaving four

one zero for two thousand six hundred.” The controller acknowledged the transmission. 

The CVR recorded the captain making several remarks related to crew scheduling

and rest issues. About 0120:01, the captain stated, “if this round trip is more than a nine

hour trip, we might get a little something...with eight hours, we get nothing...eight hours

8 VOR/DME stands for very high frequency omnidirectional radio range/distance measuring

equipment. DME is expressed in miles. 

9 Appendix B contains the CVR transcript. The transcript expresses the times of the CVR comments

and sounds in coordinated universal time (UTC). Guam local time is 10 hours ahead of UTC time.

10 The ILS is a precision approach system that provides lateral guidance (localizer) and vertical

alignment (glideslope) with the runway. The system uses ground-based radio transmitters that provide both

the localizer and the glideslope signals. See sections 1.6.2.3 and 1.10.2 for additional information.

11 TOD is the departing cruise altitude.

12 The FLAKE intersection is 7 DME from the NIMITZ VOR and is on the 242° radial. An intersection

can be defined by the crossing of two radials or by a specific distance on a bearing from a navigational aid.

13 An ILS approach can either be flown as a “full ILS” precision approach or a localizer-only,

nonprecision approach. The criteria for both approaches are often presented on the same chart. For

information on how the accident flight crew was to execute the nonprecision, localizer-only approach for

runway 6L, see section 1.10.3.1. 
Factual Information 3 Aircraft Accident Report

do not help us at all.”14 The captain also stated that “they make us work to maximum, up

to maximum....” About 0120:28, the captain further stated, “probably this way

[unintelligible words], hotel expenses will be saved for cabin crews, and maximize the

flight hours. Anyway, they make us [747] classic guys work to maximum.”15 About

0121:13, the captain stated, “eh...really...sleepy.”

About 0121:59, the first officer stated, “captain, Guam condition is no good.”

About 0122:06, the CERAP controller informed the flight crew that the automatic

terminal information service (ATIS) information Uniform16 was current and that the

altimeter setting was 29.86 inches of mercury (Hg). About 0122:11, the first officer

responded, “Korean eight zero one is checked uniform;” his response did not acknowledge

the altimeter setting. About 0122:26, the captain stated, “uh...it rains a lot.” About

0123:45, the captain stated, “request twenty miles deviation later on...to the left as we are

descending.” About 0124:02, the first officer questioned, “don’t you think it rains more?

in this area, here?” The captain then stated, “left, request deviation” and “one zero mile.”

About 0124:30, the controller approved the first officer’s request to deviate “...one zero

mile left of track [for weather].”

The CVR then recorded about 6 minutes of discussion among the flight crew

regarding the weather conditions and the deviation around the weather. About 0126:25,

the flight engineer stated, “it’s Guam, Guam.” About 0131:17, the first officer reported to

the CERAP controller that the airplane was “...clear of Charlie Bravo [cumulonimbus

clouds]” and requested “radar vectors for runway six left.” The controller instructed the

flight crew to fly a heading of 120°. After this transmission, the flight crew performed the

approach checklist and verified the radio frequency for the ILS to runway 6L.

About 0138:49, the CERAP controller instructed flight 801 to “...turn left heading

zero nine zero join localizer;” the first officer acknowledged this transmission. At that

time, flight 801 was descending through 2,800 feet msl with the flaps extended 10° and

the landing gear up. About 0139:30, the first officer said, “glideslope [several

unintelligible words]...localizer capture [several unintelligible words]...glideslope...did.”

About 0139:44, the controller stated, “Korean Air eight zero one cleared for ILS runway

six left approach...glideslope unusable.”17 The first officer responded, “Korean eight zero

one roger...cleared ILS runway six left;” his response did not acknowledge that the

glideslope was unusable.

14 The accident flight was scheduled to remain on the ground at Guam for 3 1⁄2 hours and then return to

Seoul at 0930 (0830 Seoul local time). 

15 In the aviation industry, a “747 classic” refers to the -100, -200, -300, and -SP (special purpose)

models of the Boeing 747 airplane. Classic 747s have three crewmember seats and mostly analog

(mechanical) gauges. 

16 ATIS information Uniform noted the Notice to Airmen (NOTAM) for runway 6L, which stated that

the ILS glideslope was “out of service until further notice.” See section 1.7.1.

17 The CERAP controller did not advise the flight crew of its position. FAA Order 7110.65, “Arrival

Instructions,” section 5-9-4, paragraph (a) states that a controller is to provide the flight crew with a

“position relative to a fix on the final approach course. If none is portrayed on the radar display or if none is

prescribed in the procedure, issue position information relative to the navigation aid which provides final

approach guidance or relative to the airport.” 
Factual Information 4 Aircraft Accident Report

According to the CVR, about 0139:55 the flight engineer asked, “is the glideslope

working? glideslope? yeh?” One second later, the captain responded, “yes, yes, it’s

working.” About 0139:58, an unidentified voice in the cockpit stated, “check the

glideslope if working?” This statement was followed 1 second later by an unidentified

voice in the cockpit asking, “why is it working?” About 0140:00, the first officer

responded, “not useable.” 

About 0140:06, the CVR recorded the sound of the altitude alert system18 chime.

According to information from the flight data recorder (FDR), the airplane began to

descend about 0140:13 from an altitude of 2,640 feet msl at a point approximately 9 nm

from the runway 6L threshold (5.7 nm from the NIMITZ VOR). About 0140:22, an

unidentified voice in the cockpit said, “glideslope is incorrect.” About 0140:33, as the

airplane was descending through 2,400 feet msl, the first officer stated, “approaching

fourteen hundred [feet].” About 4 seconds later, when the airplane was about 8 nm from

the runway 6L threshold, the captain stated, “since today’s glideslope condition is not

good, we need to maintain one thousand four hundred forty [feet]. please set it.” An

unidentified voice in the cockpit then responded, “yes.” About 0140:42, the CERAP

controller instructed flight 801 to contact the Agana control tower; the first officer

acknowledged the frequency change. The first officer contacted the Agana tower about

0140:55 and stated, “Korean air eight zero one intercept the localizer six left.” Shortly

after this transmission, the CVR again recorded the sound of the altitude alert chime, and

the FDR data indicated that the airplane was descending below 2,000 feet msl at a point

6.8 nm from the runway threshold (3.5 nm from the VOR).

About 0141:01, the Agana tower controller cleared flight 801 to land. About

0141:14, as the airplane was descending through 1,800 feet msl, the first officer

acknowledged the landing clearance, and the captain requested 30° of flaps. No further

communications were recorded between flight 801 and the Agana control tower. 

About 0141:31, the first officer called for the landing checklist. About 0141:33,

the captain said, “look carefully” and “set five hundred sixty feet” (the published MDA).

The first officer replied “set,” the captain called for the landing checklist, and the flight

engineer began reading the landing checklist. About 0141:42, as the airplane descended

through 1,400 feet msl, the CVR recorded the sound of the ground proximity warning

system (GPWS)19 radio altitude callout “one thousand [feet].” One second later, the

captain stated, “no flags gear and flaps,” to which the flight engineer responded, “no flags

gear and flaps.” About 0141:46, the captain asked, “isn’t glideslope working?” There was

no indication on the CVR that the first officer and flight engineer responded to the this

question. About 0141:48, the captain stated, “wiper on.”20 About 0141:53, the CVR

recorded the sound of the windshield wipers starting. The windshield wipers remained on

throughout the remainder of the flight. 

18 The altitude alert system provides visual and aural signals when approaching or deviating from the

selected altitude. See section 1.6.2.1 for more information. 

19 A GPWS is designed to provide the flight crew with visual and aural warnings when proximity to

terrain, closure rate, descent rate, bank angle, and glideslope deviation become excessive. For more

information, see sections 1.6.2.2 and 1.18.2.
Factual Information 5 Aircraft Accident Report

About 0141:53, the first officer again called for the landing checklist, and the flight

engineer resumed reading the checklist items. About 0141:59, when the airplane was

descending through 1,100 feet msl at a point about 4.6 nm from the runway 6L threshold

(approximately 1.3 nm from the VOR), the first officer stated “not in sight?” One second

later, the CVR recorded the GPWS radio altitude callout of “five hundred [feet].”

According to the CVR, about 2 seconds later the flight engineer stated “eh?” in an

astonished tone of voice. 

About 0142:05, the captain and flight engineer continued the landing checklist.

About 0142:14, as the airplane was descending through 840 feet msl and the flight crew

was performing the landing checklist, the GPWS issued a “minimums minimums”

annunciation followed by a “sink rate” alert21 about 3 seconds later. The first officer

responded, “sink rate okay” about 0142:18; FDR data indicated that the airplane was

descending 1,400 feet per minute at that time. 

About 0142:19, as the airplane descended through 730 feet msl, the flight engineer

stated, “two hundred [feet],” and the first officer said, “let’s make a missed approach.”

About 1 second later, the flight engineer stated, “not in sight,” and the first officer said,

“not in sight, missed approach.” About 0142:22, as the airplane descended through

approximately 680 feet msl, the FDR showed that the control column position began

increasing (nose up) at a rate of about 1° per second, and the CVR indicated that the flight

engineer stated, “go around.” When the captain stated “go around” about 1 second later,

the airplane’s engine pressure ratios and airspeed began to increase. However, the rate of

nose-up control column deflection remained about 1° per second. At 0142:23.77, as the

airplane descended through 670 feet msl, the CVR recorded the sound of the autopilot

disconnect warning. At 0142:24.05, the CVR began recording sequential GPWS radio

altitude callouts of “one hundred...fifty...forty...thirty...twenty [feet].” About 0142:26,

the airplane impacted hilly terrain at Nimitz Hill, Guam, about 660 feet msl and about

3.3 nm from the runway 6L threshold. FDR data indicated that, at the time of initial

ground impact, the pitch attitude of the airplane was increasing through 3°. The accident

occurred at 13° 27.35 minutes north latitude and 144° 43.92 minutes east longitude during

the hours of darkness. The CVR stopped recording about 0142:32. 

Figure 1 shows the instrument approach chart for the Guam runway 6L ILS

procedure that was in effect at the time of the accident. Figures 2 and 3 show FDR

information for the last 5 1⁄2 minutes of flight, along with CVR comments and sounds and

air traffic control (ATC) data. 

20 According to FAA radar data and CVR information, the captain’s call for the windshield wipers to be

activated occurred when the airplane was in the vicinity of the outer marker, which was located 1.6 DME

from the NIMITZ VOR.

21 This alert occurs when the GPWS computer determines that the barometric sink rate of the airplane,

beginning at 2,450 feet above ground level (agl), exceeds the designed threshold sink rate value. The

threshold value for approximately 200 feet agl is 1,200 feet per minute.
Factual Information 6 Aircraft Accident Report

Figure 1. Instrument approach chart for the Guam International Airport 

runway 6L ILS procedure.

Reproduced with the permission of Jeppesen Sanderson, Inc. NOT TO BE USED FOR NAVIGATION.
Note: Only selected CVR excerpts are shown. Appendix B contains a complete record of all CVR information and a legend of ATC 

Figure 2. Side view of FAA radar data with selected ATC and CVR communication excer
Note: Only selected CVR excerpts are shown. Appendix B contains a complete record of all CVR information and a legend of A

Figure 3. Overhead view of FAA radar data with selected ATC and CVR communication e
Factual Information 9 Aircraft Accident Report

1.2 Injuries to Persons

1.3 Damage to Airplane

The airplane was destroyed by impact forces and a postcrash fire. The estimated

value of the airplane was about $60 million.

1.4 Other Damage

The accident caused extensive ground scarring and fire damage to trees and foliage

along the wreckage path and in the immediate vicinity of the main wreckage area. Also, a

12-inch fuel oil pipeline located along a vehicle access road that services the NIMITZ

VOR was severed when it was struck by the airplane. The severed pipeline spilled about

1,000 gallons of oil in a localized area. 

1.5 Personnel Information

1.5.1 The Captain

The captain, age 42, was hired by Korean Air on November 2, 1987. He was

previously a pilot in the Republic of Korea Air Force. He held an Airline Transport Pilot

(ATP) certificate issued by the Korean Ministry of Construction and Transport (MOCT)22

on April 19, 1992, with type ratings in the Boeing 727 and 747. The captain qualified as a

727 first officer on December 19, 1988, and as a 747 first officer on February 13, 1991. He

upgraded to 727 captain on December 27, 1992, and 747 captain on August 20, 1995. The

Table 1. Injury chart.

Injuries Flight Crew Cabin Crew Passengers Other Total

Fatal 3 11 214 0 228

Serious 0 3 23 0 26

Minor 0 0 0 0 0

None 0 0 0 0 0

Total 3 14 237 0 254

22 The Korean MOCT is similar in function to the U.S. Department of Transportation (DOT). The

Korean Civil Aviation Bureau (KCAB), a division within the MOCT, is responsible for overseeing the

Korean civil airlines. For more information on the KCAB, see section 1.17.6.1.
Factual Information 10 Aircraft Accident Report

captain held Korean and FAA First Class Airman Medical certificates, both issued on

March 13, 1997, without limitations. 

According to Korean Air records, the captain had accumulated a total of 8,932 hours

of flight time, 2,884 hours as a military pilot and 6,048 hours as a civilian pilot. He had

logged a total of 1,474 and 1,718 hours as a 747 first officer and captain, respectively. Also,

Korean Air’s 747 chief pilot stated, in a postaccident interview, that the captain had received

a Flight Safety Award in May 1997 from the company president for successfully handling an

in-flight emergency involving a 747 engine failure at a low altitude.

The captain had flown 235, 144, 90, and 17 hours in the last 90, 60, 30, and 7 days,

respectively, before the accident. Between December 1992 and August 1993, he had flown

from Seoul to Guam eight times as a 727 captain. In addition, he had flown from Seoul to

Guam as a 747 captain on July 4, 1997 (about 1 month before the accident). National

Transportation Safety Board investigators interviewed the first officer from the July 4,

1997, flight. That first officer stated that the captain had contacted him by telephone 1 day

before the trip and proposed that they obtain a charter briefing for Guam because they did

not regularly conduct 747 operations at that airport. Consequently, the captain and first

officer arrived several hours before the trip departure time and received a charter briefing

from a Korean Air instructor, even though the briefing was not required. The captain and

first officer watched the Guam airport familiarization video presentation23 and studied the

approach charts for the airport. During that time, the captain commented that the area

where the NIMITZ VOR is located was mountainous and required extra attention

(referring to this area as a “black hole”). The first officer said the trip to Guam was routine

and that the weather was good, with scattered cumulous clouds and good visibility at the

airport. Further, the first officer said that the captain briefed and executed the ILS 6L

approach to a routine landing.24

The captain’s last route check was on a round trip flight from Seoul to Narita,

Japan, on July 19, 1997. A company check airman told Safety Board investigators that,

although the weather conditions at Narita and Seoul were above instrument approach

minimums, the captain executed the full ILS approach to each airport and received an

“above standard” evaluation for the flights. The captain’s last proficiency check was

conducted in a Korean Air 747 simulator on June 11, 1997. According to Korean Air, the

captain executed a nonprecision VOR/DME approach to runway 32L at Kimpo Airport

during the proficiency check. The simulated weather conditions for the approach were

900 feet overcast and winds 290° at 11 knots. The captain received an “excellent”

evaluation. A Korean Air representative told Safety Board investigators that the captain

had passed the company’s Level 3 Pilot English Test25 and had attended crew resource

23 For information on Korean Air’s airport familiarization video presentation program, see section

1.17.3.2.

24 The first officer from the July 4, 1997, trip to Guam also indicated that the captain had used the

ground time between that flight and the return trip to sleep in a seat in the first class compartment.

25 Korean Air’s Level 3 Pilot English Test comprises written, listening, and oral sections. An ATCrelated part in the listening section “tests correct understanding and proper usage of ATC transmissions,

ATIS broadcasts, [and] ATC terminology/phraseology.” All Korean Air pilots are required to pass this test.
Factual Information 11 Aircraft Accident Report

management (CRM) training from October 24 to 27, 1989. The captain had not flown with

the flight 801 first officer before the accident flight.

Korean Air records indicated that the captain flew a round trip flight sequence

from Seoul to San Francisco, California, from July 28 to July 30, 1997. He was off-duty

until August 2, when he flew two round trip domestic flights between the hours of 1100

and 2000.26 On August 3, the captain flew an international trip to Hong Kong that arrived

in the early evening. The return flight was delayed because of inclement weather. The

captain remained in Hong Kong overnight and flew back to Seoul the next morning,

arriving about 1230.

After the accident, the captain’s wife told Safety Board investigators, through a

family representative, that the captain normally awoke between 0600 and 0630 and went to

bed between 2200 and 2300. She stated that, on August 2, the captain awoke between 0600

and 0630 and went to bed about 2300. On August 3, the captain awoke about 0630 for the

trip to Hong Kong and remained there overnight. The captain’s wife stated that, after

arriving home on August 4 from the trip, he was involved in routine activities and went to

bed at his accustomed time. According to the captain’s wife, on August 5, he awoke at

0600, worked out in a gym for an hour and returned home for breakfast. He later studied the

flight schedule for the trip to Guam, took a nap from 1100 to 1340, and then ate lunch. She

also stated that the captain departed for the 20-minute drive to Kimpo Airport about 1500

and that the captain had left early to allow time to prepare for the flight to Guam.

1.5.2 The First Officer

The first officer, age 40, was hired by Korean Air on January 10, 1994. He was

previously a pilot in the Republic of Korea Air Force. He held an ATP certificate issued by

the FAA on July 10, 1994, and a Korean ATP certificate issued by the MOCT on

March 28, 1997. He received a 747 type rating on March 11, 1995, and qualified as a 747

first officer on July 23, 1995. The first officer held Korean and FAA First Class Airman

Medical certificates, both issued on June 13, 1997, with no limitations.

According to company records, the first officer had accumulated a total of

4,066 hours of flight time, 2,276 hours as a military pilot and 1,790 hours as a civilian

pilot. He had logged a total of 1,560 hours as a 747 first officer. The first officer had flown

189, 132, 67, and 20 hours in the last 90, 60, 30, and 7 days, respectively, before the

accident. The first officer had flown from Seoul to Guam in August and September 1995

as a 747 first officer. According to company records, he viewed the Guam airport

familiarization video on July 8, 1997, in preparation for a future flight to Guam. 

The first officer’s last route check was conducted in July 1995. The first officer’s

last proficiency check was conducted in a Korean Air 747 simulator on March 28, 1997.

During the proficiency check, the first officer executed a nonprecision VOR/DME

approach to runway 32L at Kimpo Airport. The simulated weather conditions for the

26 The times in sections 1.5.1 through 1.5.3 are expressed in Seoul local time, based on a 24-hour clock.
Factual Information 12 Aircraft Accident Report

approach were clouds 900 feet broken and winds 260° at 11 knots. An instructor noted, in

an overall simulator session evaluation, that the first officer’s “control skills and

knowledge [were] above standard.” The first officer received a “standard” evaluation for

his nonprecision VOR approaches. However, the instructor noted that the “altitude

management on nonprecision approach [was] somewhat less than desirable.” Another

instructor noted that the first officer was “somewhat slow to carry out directions.”

According to Korean Air records, the first officer had passed the Level 3 Pilot English

Test but had not attended CRM training. 

Korean Air records indicated that the first officer returned from an international

trip to the United States on the afternoon of August 2, 1997. He was off-duty on August 3

and flew a round trip domestic flight on August 4, 1997, between 0930 and 1245. The first

officer was then off-duty until the accident flight. Safety Board investigators interviewed

the first officer’s relatives after the accident. They stated that he telephoned his mother

about 1700 on August 5 and that “everything seemed routine.” Because his family lived in

New Zealand, the first officer’s relatives could not be specific about his activities before

the accident flight.

1.5.3 The Flight Engineer 

The flight engineer, age 57, was hired by Korean Air on May 7, 1979. He was

previously a navigator in the Republic of Korea Air Force. He obtained his flight

engineer’s certificate on December 29, 1979, and was qualified on the Boeing 727 and 747

and Airbus A300 airplanes. The flight engineer held a Korean First Class Airman Medical

Certificate issued on June 5, 1997. According to company records, the flight engineer had

accumulated a total of 13,065 hours of flight time, including 11,088 hours as a flight

engineer (1,573 hours of which were as a flight engineer on the 747). Korean Air records

also indicated that the flight engineer had flown 165, 120, 77, and 28 hours in the last 90,

60, 30, and 7 days, respectively, before the accident.

The flight engineer’s last two route checks were in April 1997. He received an

“above standard” evaluation for the first route check and an “excellent” evaluation for the

second route check. The flight engineer’s last proficiency check was in a Korean Air 747

simulator on March 7, 1997. He received an “above standard” evaluation for the session,

and an instructor note stated, “control skills and knowledge are above standard.” The

flight engineer’s crew coordination was also rated as “above standard.” According to

Korean Air records, the flight engineer passed the Level 3 Pilot English Test and attended

CRM training from April 28 to May 1, 1987. A Korean Air official indicated that the

flight engineer had never flown to Guam.

The flight engineer had returned to Seoul on August 3, 1997, after completing a

3-day international trip to Anchorage, Alaska, and San Francisco. Although he was offduty on August 4 and was assumed to have engaged in routine activities at home, the flight

engineer’s wife and son could not provide Safety Board investigators with details of his

activities or sleep patterns before the accident flight.
Factual Information 13 Aircraft Accident Report

1.5.4 The Flight Attendants

Fourteen flight attendants were working on the accident flight. The lead flight

attendant (or purser), age 37, had been hired by Korean Air on July 18, 1988. According to

company records, the purser had completed her basic training on August 28, 1988, and her

most recent recurrent training was completed on December 10, 1996.

One flight attendant, age 43, was hired by Korean Air in August 1981; the other

12 flight attendants, ranging in age from 21 to 25, were hired between November 1992

and March 1997. According to company records, all had completed their basic training,

and their most recent recurrent training was completed between June 1996 and April 1997.

1.5.5 The Air Traffic Controllers 

1.5.5.1 Combined Center/Radar Approach Control

The CERAP controller, age 39, was hired by the FAA on May 30, 1982, in Los

Angeles, California, and initially qualified as a terminal radar approach control

(TRACON) controller. He transferred to the Guam CERAP facility on September 3,

1995,27 where he was certified as a full-performance level controller. Before his

employment with the FAA, the controller worked as a radar and tower controller in the

U.S. Navy. His last duty station in the Navy was at Naval Air Station Cubi Point,

Philippines, from 1978 to 1982. He was medically certified as a controller without waivers

or limitations.

1.5.5.2 Air Traffic Control Tower 

The Agana tower controller, age 39, was hired by Barton ATC International, Inc.—

a nonfederal contract ATC service company—as an air traffic controller at the Guam

Federal Control Tower on May 15, 1995.28 According to company and FAA records, the

controller was fully certified on all positions of operations in the tower, including

clearance delivery, ground control, local control, and controller-in-charge. He was

medically qualified for his duties and held an FAA Second Class Airman Medical

Certificate issued on April 9, 1997, without waivers or limitations. 

Before his employment with Barton ATC International, the controller held a

similar position in the U.S. Navy from 1983 to 1992. During this time, the controller was

trained and qualified in various TRACON positions, including radar approach control,

arrival radar, radar final, departure radar, and precision and surveillance radar. He was

assigned to the Naval Air Station Agana tower in 1989. The controller told Safety Board

investigators that, at the Agana Naval tower, he was qualified in all tower positions and

worked as a flight data controller, radar final controller, tower supervisor, facility watch

27 For information on the CERAP facility, see section 1.10.1.1.

28 For information on the Agana tower facility, see section 1.10.1.3.
Factual Information 14 Aircraft Accident Report

supervisor, and radar branch chief. The controller remained on Guam after he was

discharged from the Navy. 

1.6 Airplane Information

The accident airplane, HL7468, serial number 22487, was one of three Boeing

747-300s in Korean Air’s fleet. The airplane was delivered new to the company on

December 12, 1984, and had been operated and maintained continuously by Korean Air

until the accident. Every Korean-registered aircraft is subject to annual renewal of its

airworthiness certificate from the Korean Civil Aviation Bureau (KCAB); this airplane’s

last airworthiness certificate was issued on July 7, 1997.

At the time of the accident, the airplane had accumulated about 50,105 hours total

time in service and about 8,552 cycles.29 The airplane was equipped with four Pratt &

Whitney JT9D-7R4G2 engines with total times and cycles since new of 26,014 hours and

4,699 cycles (No. 1), 36,611 hours and 6,137 cycles (No. 2), 25,904 hours and 4,383

cycles (No. 3), and 33,889 hours and 5,701 cycles (No. 4). The most recent engine change

before the accident was the replacement of the No. 3 engine on June 11, 1997, after a

compressor surge incident.

According to Korean Air, the airplane was maintained according to the company’s

Continuous Maintenance Program, which was approved by the KCAB. The maintenance

program comprised “A” checks performed at 350-hour intervals and “C” checks at

4,000-hour intervals. (Approximately 12 A checks are performed between each C check.)

The last A check was performed on July 12, 1997, at 49,874 hours. The last C check was

performed on December 16, 1996, at 47,918 hours. During the C check,

operational/functional test work cards were completed for the transponders, radar

altimeters, VOR/ILS navigation receivers, central air data computers, GPWS, autopilot,

automatic direction finder (ADF), altitude alert, inertial navigation systems, weather radar,

DME, and high-frequency radios. Further, the FDR was read out, and the altimeters were

calibrated.

1.6.1 Maintenance Discrepancies Before the Accident Flight

The accident airplane’s logbooks indicated that, from December 1996 (the time of

the last C check) to August 1997, all mechanical discrepancies identified by flight crews

or maintenance personnel had been corrected before the next scheduled flight. Several

discrepancies were deferred, in accordance with Korean Air minimum equipment list

guidelines, and the airplane was flown to Seoul for repair. The airplane’s logbook entries

during this time period detailed the following maintenance deficiencies and corrective

actions:

29 A cycle is one complete takeoff and landing sequence.
Factual Information 15 Aircraft Accident Report

• Between December 18, 1996, and January 5, 1997, five airspeed-related

writeups were logged, including one that identified a discrepancy of up to

50 knots between the captain’s and first officer’s airspeed indicators while in

cruise. Corrective actions were taken.

• On April 9, 1997, the GPWS failed the “below glideslope” test. Contamination

was cleaned from a connector.

• Between May 3, 1997, and June 23, 1997, six writeups were logged about

erroneous fuel quantity indications on the No. 1 fuel quantity indicator. The

system was checked after each event.

• On July 3, 1997, the first officer’s altimeter was replaced.

• On July 30, 1997, during an autocoupled approach at Seoul, autopilot channel

“A” disengaged at a radar altitude of 1,000 feet. (According to a Boeing

representative, because the autopilot is a triple-redundant system, it would

have continued to control the airplane using the “B” and “C” channels.) A pin

on one of the autopilot system’s electrical connectors was subsequently

cleaned.

Korean Air records indicated that the accident airplane had no deferred

maintenance items when it was dispatched on August 5, 1997, and that no discrepancies

had been identified in the airplane’s logbook for the previous 12 flights. The partially

completed logbook page for the accident flight was recovered from the wreckage, and no

maintenance writeups had been logged. 

1.6.2 Cockpit Instrumentation

The captain’s and first officer’s instrumentation panels from the Boeing 747

Classic are shown in figures 4 and 5, respectively. A discussion of the accident airplane’s

autopilot system, GPWS, and ILS follows.

1.6.2.1 Autopilot System

The accident airplane was equipped with a Sperry-Rand (now Rockwell Collins)

autopilot, model SPZ1. The autopilot system consists of a mode control panel and three

pitch and roll computers (with a landing rollout function) that drive the pitch and roll

actuators. In addition, two separate yaw damper computers provide control to the “split”

rudder system (two individual rudder panels).

Boeing engineers stated that, when the autopilot’s ILS mode is selected by the pilot

and a sufficient glideslope signal exists, the glideslope “armed” indicator is annunciated in

the cockpit with an amber light. The pitch and roll computers maintain pitch control and

operate in any of the following modes: “Altitude Hold,” “Altitude Select,” “Indicated

Airspeed Hold,” or “Vertical Speed.” When the deviation of the glideslope signal reaches

a predetermined level, the vertical beam sensor automatically switches the landing rollout

computer function to control the pitch axis of the elevator. The glideslope signal is
Factual Information 16 Aircraft Accident Report

Figure 4. Captain’s instrumentation panel.

Reproduction courtesy of The Boeing Company.
Factual Information 17 Aircraft Accident Report

Figure 5. First officer’s instrumentation panel.

Reproduction courtesy of The Boeing Company.
Factual Information 18 Aircraft Accident Report

validated before the system can arm the glideslope “engage” logic and the vertical beam

sensor. According to Boeing, if the glideslope signal is invalid, the failure will be

annunciated in the cockpit with a steady red “autopilot” warning light.

The altitude alert system is coupled to the autopilot. The altitude alert is armed by

the pilot when the desired altitude is set into the “ALT SEL” (altitude select) window on

the pilot’s control panel (or glareshield). The amber “ALTITUDE ALERT” light

illuminates steadily, and a 2-second aural tone sounds when the aircraft is approaching the

selected altitude from either 900 feet above or below. The light remains illuminated until

the aircraft is within 300 feet of the desired altitude. The light then flashes, and the

2-second aural tone sounds when the aircraft deviates 300 feet above or below the selected

altitude until the deviation exceeds 900 feet, at which time the light extinguishes and the

system automatically resets for subsequent altitude alerting. The “deviation from altitude”

mode of the altitude alert system deactivates when the landing gear is extended.

1.6.2.2 Ground Proximity Warning System

The accident airplane was equipped with an AlliedSignal Mark VII GPWS

Warning Computer.30 The mode 2 warnings “TERRAIN” and “PULL UP” were

desensitized31 during flight 801’s approach while the airplane was in the landing

configuration (gear down/flaps extended). The advisories and alerts that remained active

in the landing configuration were those for excessive descent rate (sink rate); excessive

terrain closure rate; excessive glideslope deviation; minimums (radio altitude decision

height) callout; and 1,000, 500, 100, 50, 40, 30, 20, and 10 feet radio altitude callouts.32

On October 3, 1997, postaccident testing of the GPWS installed on flight 801 was

performed at AlliedSignal facilities in Redmond, Washington. The testing found that the

GPWS was capable of normal operation.

1.6.2.3 Instrument Landing System

The accident airplane was equipped with three Rockwell International/Collins

Model 51RV-5B ILS receivers. No recorded malfunctions or abnormalities with the three

receivers were recorded between the time of their respective installations (from November

1996 to May 1997) and the accident. 

30 For general information on GPWS, see section 1.18.2.1. For information on previous safety

recommendations on GPWS and related systems, see section 1.18.2.4.

31 Desensitizing changes the range of values to which the alerts respond to minimize nuisance warnings.

Desensitizing does not suppress or cancel (inhibit) the alerts. A terrain closure rate must exceed 2,500 feet

per minute to initiate a warning during the time that the terrain and pull up warnings are desensitized. 

32 According to the Boeing 747 Operations Manual used by Korean Air, activation of the pull up alert

(which was desensitized in the landing configuration) requires the recovery maneuver (see section 1.17.4.3)

immediately unless daytime VFR conditions exist and a positive visual verification is made that no hazards

exist. The operations manual further states that flight crews should respond to terrain, don’t sink, sink rate,

too low gear, and glideslope alerts by correcting “flightpath and/or airplane configuration to eliminate the

cause of the aural alert.” 
Factual Information 19 Aircraft Accident Report

In a normally functioning system, ILS information is displayed in the cockpit on

the captain's and first officer's raw data indicators on the attitude director indicator (ADI)

and the horizontal situation indicator (HSI) if they are receiving localizer and glideslope

information. In addition, the ADI’s flight directors (FD) display ILS information if the

appropriate FD mode is selected.33 The ADI and HSI are equipped with a warning flag

that is displayed over the ILS indications (localizer and glideslope) to alert a pilot if either

the ground or airborne system fails or if the receivers are not set to the correct radio

frequency.34

According to the manufacturer, the glideslope warning flag will appear if the

navigation receiver is tuned to an ILS frequency and any of the following conditions exist:

• there is an absence of a glideslope radio-frequency signal or 90- and 150-Hertz

(Hz) modulations;

• the percentage of modulation of either the 90- or 150-Hz signal is reduced to

zero and the other is sustained at 40 percent or more; or

• the level of a standard glideslope deviation signal produces 50 percent or less

of the standard deflection of the deviation indicator.

1.6.3 Weight and Balance

The weight and balance form signed by the captain and the dispatcher for the

accident flight included the following data:35

• zero fuel weight, 197,897 kilograms (kg);

• departure fuel, 51,847 kg;

• trip fuel, 36,923 kg;

• takeoff weight, 249,744 kg;

• estimated landing weight, 212,821 kg;

• passenger weight (including cabin baggage), 17,694 kg;

• cargo in compartments, 7,333 kg;

• takeoff weight center of gravity, 24 percent mean aerodynamic cord; and

• takeoff stabilizer trim setting, 4.4 units.

33 The flight mode annunciator (FMA), although not a part of the ILS system, indicates the mode for the

FD and autopilot. The NAV mode selector switch determines what a flight crew expects to see on the FMA.

“Armed” is indicated with white letters on a black background; “capture” is indicated with black letters on a

green background. The radio magnetic indicator is used to determine VOR passage if the needles are set to

VOR (and not to the ADF). 

34 The FD is equipped with command bars. In a precision approach, the command bars provide guidance

to maintain the glideslope; in a nonprecision approach, the command bars typically provide guidance to

maintain the desired vertical speed. 

35 The maximums for zero fuel weight, takeoff weight, and estimated landing weight were 242,630,

377,777, and 265,306 kg, respectively.
Factual Information 20 Aircraft Accident Report

1.7 Meteorological Information

1.7.1 Weather Conditions at Guam International Airport

Guam’s climate is relatively uniform throughout the year. Guam averages 247 days

each year with measurable amounts of precipitation (rain), and most days begin with

scattered layers of clouds that become broken to overcast by afternoon.

From August to October, visual meteorological conditions (VMC) prevail about

80 percent of the time, and instrument meteorological conditions (IMC) prevail

predominately during the afternoon hours. The rainy season lasts from July to November.

During that time, precipitation averages about 24 days per month, and the prevailing

winds are usually from the east, averaging about 9 knots.

A weather synopsis prepared by the Guam National Weather Service (NWS)

Office on the day of the accident stated:

...a weak low pressure trough is moving slowly [through] the Mariana

Islands...resulting in gentle to moderate easterly winds and scattered showers.

The effects of the upper level low far to the northeast have diminished during the

past 12 hours or so. Light to moderate showers should be expected except for

isolated afternoon thunderstorms due to solar heating. 

About 0122:06 during the accident flight, the flight crew was informed by the

CERAP controller that ATIS information Uniform was current. The content of that report

was as follows:

Agana tower information UNIFORM, time one four five zero zulu, wind calm,

visibility seven, [clouds] one thousand six hundred scattered, two thousand five

hundred scattered, temperature two seven [Celsius], dew point two four, altimeter

two niner eight six, runway six in use. NOTAMs [Notices to Airmen36], runway

six left ILS glideslope out of service until further notice, advise on contact you

have information UNIFORM.

The special surface weather observation for 0132 on August 6, 1997, was as

follows: 

Wind 090° at 6 knots; visibility—7 miles; present weather—shower vicinity; sky

condition—scattered 1,600 feet, broken 2,500 feet, overcast 5,000 feet;37

temperature—27° C; dew point—25° C; altimeter setting 29.85 inches Hg;

remarks—showers vicinity northwest-northeast.

36 NOTAMs are disseminated to flight crews to provide information about conditions or changes in any

aeronautical facility, service, procedure, or hazard.

37 In surface weather observations, cloud bases are measured in feet agl.
Factual Information 21 Aircraft Accident Report

The special surface weather observation for Guam International Airport for 0147

on August 6 was as follows:

Wind variable at 4 knots; visibility—5 miles; present weather—light rain shower;

sky condition—few 1,500 feet, scattered 2,500 feet, overcast 4,000 feet;

temperature 26° C; dew point 24° C; altimeter 29.85 inches Hg.

The Safety Board examined the NWS surface weather observation logs and found

that heavy rain showers were reported at the airport between 0020 and 0029, between

0114 and 0116, and between 0153 and 0158. The weather logs also indicated that light rain

showers were reported at the airport between 0016 and 0020, between 0029 and 0033,

between 0106 and 0114, between 0116 and 0128, and between 0138 and 0148. Further,

light rain and mist were also reported between 0148 and 0153. The maximum windspeed

recorded at the airport between 0130 and 0150 was about 10 knots.

The following terminal aerodrome forecast (TAF) for Guam International Airport,

which was issued by the NWS on August 6 at 0030 as an amendment to an earlier TAF,

was valid at the time of the accident:

Wind 120° at 7 knots, visibility greater than 6 miles, scattered 1,600 feet scattered

4,000 feet scattered 8,000 feet overcast 30,000 feet. Temporary August 6, 0100 to

August 6, 0600, wind 130° at 12 knots gusting 20 knots, visibility 3 miles, heavy

rain shower, broken 1,500 feet cumulonimbus overcast 4,000 feet. 

The radar antenna of the Guam Weather Surveillance Radar-1988, Doppler

(WSR-88D) was located about 5 nm east of the accident site. Data recorded about 0143 on

August 6 (1543 UTC time on August 5, 1997) indicated an area of precipitation over

higher terrain about 4 nm southwest of the airport, including Nimitz Hill. The

precipitation was oriented east to west, about 7 to 8 nm long and 3 to 4 nm wide, and was

moving toward the west. Figure 6 shows the WSR-88D four-panel base reflectivity

product for 0143.

1.7.2 Air Traffic Control Weather Information

The CERAP radar controller stated that, although areas of weather were in the

vicinity of the VOR and airport, he had not received any pilot reports from midnight to the

time of the accident. The controller stated that a “relatively small cell,”38 which he

believed to be of light to moderate intensity, was depicted on the Airport Surveillance

Radar (ASR)-8 display. Further, the controller said that the “relatively small cell”

observed on radar extended about 3 to 5 miles on the final approach course and was about

2 to 3 miles across in the largest area. The controller said that he had no means of

determining the intensity of this or any other weather cell because, unlike other weather

radar displays, the ASR-8 radar display is monochromatic, and it is difficult to

differentiate precipitation intensity without color. However, the controller also said that he

38 The term “cell” is used to describe an area of precipitation depicted on radar.
Figure 6. WSR-88D four-panel base reflectivity product for Guam.
Factual Information 23 Aircraft Accident Report

interpreted the intensity of precipitation by the different levels of opaque (white) shading

and his experience as a controller. 

The CERAP controller stated that he did not advise the flight crew or the Agana

tower controller that he had observed the precipitation on radar while flight 801 was on

the approach course to the airport. The controller said that he had assumed that the flight

crew was using cockpit radar because they had asked him twice for deviations around

weather. The controller stated that the airplane’s cockpit radar was more accurate and

more precise than the radar he was using at the CERAP. The controller further stated that

he did not observe (on radar) the airplane entering the precipitation.

FAA Order 7110.65, “Air Traffic Control,” paragraph 2-6-4 (a) states that a

controller is to “issue pertinent information on observed/reported weather or chaff39 areas.

Provide radar navigational guidance and/or approved deviations around weather or chaff

when requested by the pilot....” Paragraph 2-6-4 (c) states that a controller is to “inform

any tower for which you provide approach control services if you have any weather

echoes on radar which might affect their operations.” Further, paragraph 2-9-2 states that,

in the event of “rapidly changing conditions,” a new ATIS is to be recorded and that the

information is to be issued by ATC. 

The Agana tower controller stated that, although it was not raining at the airport

when flight 801 was inbound, a rain shower was moving in from the northeast over the

airport and down the runway to the southwest. The tower controller said that he did not

know when the rain began at the airport because he was using binoculars to try to locate

flight 801 on the approach. He estimated that the visibility was 7 miles and stated that no

low clouds were visible.

1.7.3 Additional Weather Information

A certified Navy weather observer on Nimitz Hill, about 3⁄4 mile northwest from

the accident site, stated that the cloud ceiling about the time of the accident was

approximately 700 to 800 feet above ground level (agl), or 1,300 to 1,400 feet msl, during

a heavy rain shower. Also, he stated that visibility was about 200 to 300 meters and that

the windspeed was not more than 10 knots. The NWS forecaster on duty at the time of the

accident stated that no SIGMETs [Significant Meteorological Information] were valid for

Guam and that the night was “pretty routine.” 

The flight crew of Continental Air Micronesia flight 960, a Boeing 747 that landed

at Guam about 30 minutes before the accident, stated that visibility was “excellent” from

PAYEE intersection (located about 240 nm north of the NIMITZ VOR) and that scattered

thunderstorms were occurring around the area. Further, the pilots indicated that their

on-board radar depicted rain showers over the NIMITZ VOR but not over the airport.

They also stated the visibility was “good” under 2,000 feet and that they maintained visual

contact with the airport throughout the approach.

39 Chaff is aluminum foil strips dropped by military aircraft as phony targets to confuse radars.
Factual Information 24 Aircraft Accident Report

The flight crew of Ryan International flight 789, which landed shortly after the

accident occurred, stated that the visibility was sufficient to see the lights of Guam from

about 150 nm away. The first officer stated that on-board weather radar indicated showers

northeast of the airport but no thunderstorms. 

Additionally, the Ryan flight crew initially requested a visual approach when the

flight was about 15 nm from the VOR, but the airplane encountered clouds and rain on

approach to runway 6L shortly thereafter. The first officer stated that the airplane

remained in the clouds until it was in proximity of the VOR, at which time the airplane

broke out and the flight crew was able to acquire and maintain visual contact with the

airport. The captain stated that, although clouds and rain were over the island’s shoreline,

the air around the airport and in the vicinity of the accident site was smooth. Further, the

captain, who was also a check airman based at Guam, said that he “noticed that once

[flight] crews are given a visual approach [to Guam International Airport] they have a

tendency to press on even when they lose visual contact in hopes of regaining visual

contact again.... That’s because so many approaches are visual and the clouds and rain

showers are so localized.”

In addition, a witness who was hunting on Nimitz Hill at the time of the accident

stated that it was not raining when he observed flight 801 pass over his position (100 feet

north of the VOR beacon) and crash a very short distance away. He said that there had

been intermittent rain showers shortly before the accident but that, when he saw the

airplane crash, he could see stars directly over the accident site. The witness also said that

the visibility was “very good” at the time of the accident and that, although he could not

see the airport lights, he could see the lights of the town of Tamuning (3 to 4 miles

northeast of his location). He said that the wind was “normal” and that no thunder or

lightning was in the area.

1.8 Aids to Navigation

Guam International Airport is serviced by three navigational aids: the NIMITZ

VOR/DME (UNZ); the Mount Macajna nondirectional beacon (NDB), which was not

operational at the time of the accident; and the ILS glideslope and localizer. 

 The colocated VOR and DME transmitters were equipped with a “selfmonitoring” system that samples radiated transmitter signals to ensure that the system is

operating within prescribed tolerances and parameters. If these tolerances are exceeded,

the monitoring system automatically shuts down the equipment. According to the facility

logs, the VOR was not shut down at the time of the accident.

On the day of the accident, the FAA conducted a flight check of the localizer, outer

marker, and NDB at Guam. The VOR and DME at Guam were not checked by the FAA

until the day after the accident because of rescue operations. The FAA’s flight checks

determined that the respective systems were functioning properly and within prescribed

tolerances.40 The flight checks did not examine the glideslope because it was out of

service and removed at the time (see section 1.10.2 for more information).
Factual Information 25 Aircraft Accident Report

1.9 Communications

No communications problems were reported between the crew of flight 801 and

any of the FAA or contract ATC facilities. (See sections 1.7.2 and 1.10.1 for more

information.) 

1.10 Airport Information

The A.B. Won Pat Guam International Airport is located about 3 nm northeast of

Agana on the west-central coast of Guam at an elevation of 297 feet msl. The airport is

leased to the Guam International Airport Authority by the U.S. Navy, and the associated

navigational facilities are owned and operated by the FAA. The airport has two parallel

runways oriented northeast/southwest: runway 6R/24L, which is 8,001 feet long and

150 feet wide, and runway 6L/24R, which is 10,015 feet long and 150 feet wide. 

Runway 6L is equipped with high-intensity runway edge lights and a mediumintensity approach lighting system with runway alignment indicator lights.41 The runway

was not equipped with runway end identifier lights, centerline lights, or touchdown zone

lights. Runway 6L is also equipped with a four-box visual approach slope indicator

(VASI) calibrated for a 3° visual glidepath angle. The touchdown elevation of runway 6L

is 256 feet but rises to 297 feet at the departure end of the runway.

Guam International Airport was certified by the FAA as an Index D aircraft rescue

and firefighting (ARFF) facility under 14 CFR Part 139. In accordance with this index, the

airport is required to maintain a minimum of three ARFF vehicles capable of carrying a

total quantity of at least 4,000 gallons of water. 

1.10.1 Air Traffic Control Services for Guam International Airport

1.10.1.1 Combined Center/Radar Approach Control 

The Guam CERAP, located at Andersen Air Force Base (AFB),42 provides both

TRACON and en route ATC services. To do so, the CERAP is equipped with two

40 Although the FAA concluded that the outer marker was functioning properly, its aural alert was not

heard on the accident airplane’s CVR, and the CVR contained no indication that the flight crew had seen the

flashing blue light of the marker beacon indicator. However, the alert would not have been audible and the

indicator would not have been seen if the flight crew had turned off the marker beacon aural alert and the

marker beacon indicator. The instruments and switches related to the ILS that were found in the wreckage

did not indicate the operational status of the marker beacon aural receivers and indicators. 

41 The tower controller said that, at the time of the accident, the lights for runway 6L were on step 2, and

the medium intensity approach lights were on step 1 (the lowest of three approach light intensity settings).

These settings were not changed until after the accident when Ryan flight 789 requested that the lights on

runway 24R be changed from step 2 to 3. The controller documented the runway light settings about an hour

after the Ryan flight had landed and said that no one had reset the runway lighting panel during that period.

42 Andersen AFB is located at the northeastern end of the island. It has two runways that are oriented in

the same manner as those at Guam International Airport. 
Factual Information 26 Aircraft Accident Report

independent radar data processing systems that receive radar information from different

radar sites: terminal ATC services are provided by an Automated Radar Terminal System

(ARTS) IIA analog display processor connected to an ASR-8 radar system; en route ATC

services are provided by a digitized, narrow-band Micro-En route Automated Radar

Tracking System (EARTS) processor connected to an FPS-93 long-range radar.43 Each of

these systems independently performs its own minimum safe altitude warning (MSAW)

processing (see section 1.10.1.2) but uses different algorithms that have been optimized

for either terminal or en route operations. Both the FPS-93 and ASR-8 sensors are located

about 1,500 feet apart on Mount Santa Rosa.

The CERAP airspace comprises concentric circles centered around the Mount

Santa Rosa radar antenna site. The 250-nm-radius outer ring, which encompasses all of

the airspace from above the surface, is classified as oceanic airspace. A 100-nm-radius

inner ring, which extends over the Saipan radio beacon and from the surface to

28,000 feet, is classified as domestic airspace.44 The CERAP airspace is adjoined on all

sides by the Oakland Air Route Traffic Control Center oceanic sectors. The airspace over

Saipan and Guam is classified as approach control airspace, and its boundaries extend

from the surface to 17,000 feet. The CERAP was classified as a Level II facility at the

time of the accident.45

The CERAP facility has two en route and one approach control radar positions.

The R-1 en route radar position is responsible for the 100-nm inner circle; the R-4 en route

radar position is responsible for the 250-nm outer circle. The D-3 approach control radar

position, which is located between the en route R-1 and R-4 radar positions, is responsible

for a 25-nm inner ring that extends from the surface to 17,000 feet and includes the

NIMITZ VOR and the Andersen TACAN.46 At the time of the accident, one controller

was performing the functions of all three positions from the R-4 position.

Authorized staffing for the Guam CERAP comprises 14 full-performance level

controllers, 3 supervisors, an Automation Specialist, a Quality Assurance/Training

Specialist, an Air Traffic Manager, and a secretary. According to FAA quality assurance

staff at Guam, afternoon traffic at Guam is primarily overflights of aircraft traveling

northbound, and evening traffic is primarily aircraft traveling inbound from Asia. 

The CERAP controller on duty at the time of the accident told Safety Board

investigators that, after arriving at the facility at 2345 on August 5, 1997, he assumed the

duties at the R-4 en route radar position (and the colocated R-1 en route and D-3 approach

control radar positions). A coworker arrived at the facility and assumed the duties at the

43 The FPS-93 long-range radar system is connected to an Air Traffic Control Beacon Interrogator-5

encoder, and the ASR-8 radar system is connected to an Air Traffic Control Beacon Interrogator-4 encoder.

44 Saipan is part of the Mariana Islands.

45 At the time of the accident, ATC facilities were classified according to the number of flight operations

per hour. Level I had the lowest number of flight operations; Level V had the highest number. ATC facilities

are now classified under a different system that considers other factors in addition to the number of flight

operations per hour. 

46 TACAN stands for tactical air control and navigation. It is the U.S. military’s version of DME.
Factual Information 27 Aircraft Accident Report

D-3 position from midnight to 0110, at which time he went on a break. The controller then

resumed the duties of the D-3 position. (His coworker was not in the control room at the

time of the accident.) 

The CERAP controller stated that he was monitoring the EARTS (en route) radar

display, which was set to 265 nm (but normally covers 250 nm). The controller also said

that the en route radar display (which was located directly in front of him) was set to show

the MSAW area in the lower right corner. (Controllers are able to set radar information to

any position on the radar screen.) According to the controller, the en route radar system

was displaying only secondary radar (beacon) target information47 throughout his shift.

(The system was set up that way when he relieved the previous controller on duty.) He

said the en route radar system was not able to display weather information because the

part of the system that would normally display such information was out of service. 

Further, the CERAP controller told investigators that the TRACON radar display

(which was located to his immediate right) was set to a 60-nm range. The controller also

stated that the approach control radar was set to display the MSAW area in the lower

center of the screen. In addition, the controller said that the approach control radar was

displaying primary and secondary radar return targets48 and areas of weather that were

moving through the Guam area throughout his shift.

The CERAP controller also told investigators that the traffic complexity and

density, that is, the number of aircraft under his control, from the time of initial radio

contact with flight 801 (about 0103:18) to the time he advised the flight crew to contact

the Agana tower (about 0140:42) was “light to moderate traffic and routine complexity.”

The controller estimated that he was handling 10 to 15 aircraft during that time, including

flight 801. 

After the CERAP controller initiated the communications change (instructing

flight 801 to contact the Agana tower controller), he was still responsible for radar

monitoring of the flight because the Agana tower was a VFR facility and none of the

criteria for automatic termination of radar service, as stated in FAA Order 7110.65, “Air

Traffic Control,” paragraph 5-1-13, had been met. However, the CERAP controller was no

longer able to directly contact the airplane after it had switched to the Agana tower

frequency. 

During a postaccident interview, the controller stated that he did not monitor the

progress of flight 801 after the communications changeover because he was performing

other duties that might have precluded further monitoring. According to the transcript

from the recorded voice communications of radio and interphone lines during the period

that flight 801 was in communication with the Agana tower, the CERAP controller made a

radio transmission to another aircraft about 0140:54. From about 0141:14 to 0141:30, he

was on the interphone with a controller at the Oakland Center. About 0142:05, the CERAP

47 Secondary radars transmit interrogation pulses to a receiver aboard an aircraft. The radars display

altitude and identity information sent from the aircraft in response. 

48 Primary radar targets only detect radar energy reflected from the structure of the aircraft itself.
Factual Information 28 Aircraft Accident Report

controller acknowledged a transmission from the flight crew of Ryan International flight

789. The transcript indicated no further activity until about 0143:49, when the CERAP

controller called the Agana tower with a flight plan. The CERAP controller said that he

last observed the target of flight 801 on the terminal radar display when the airplane was

7 miles from the airport at an altitude of 2,600 feet.

Between 0150 and 0151, the CERAP controller was queried by the Agana tower

controller about flight 801. About 0154:44, the CERAP controller contacted Ryan flight

789 and stated, “ryan seven eighty nine roger we may have lost an airplane....” About

0156:03, the CERAP controller requested the Ryan flight crew to “...look for signs of an

accident west of the airport.” About 0156:35, a Ryan flight crewmember advised the

CERAP controller, “...about fifteen minutes ago we saw the clouds light up bright red it

was kinda weird we thought it was just our eyes or something.” About 0156:58, the

crewmember advised the controller, “we got a big fireball on the hillside up here...about

our three o’clock and two miles–ah a mile.” 

1.10.1.2 Minimum Safe Altitude Warning System 

Beginning in 1977, MSAW functions were incorporated into the ARTS software

installed in FAA terminal radar data processing systems.49 According to FAA technical

document NAS-MD-684, MSAW provides general terrain monitoring for all aircraft,

including those not on approach, within a predetermined geographic area and approach

path monitoring for certain aircraft operating within an approach capture box

(a rectangular area surrounding a runway and final approach course). The document also

states that aircraft on approach are to be monitored based on their current or predicted

altitude compared with the lowest MDA for the approach and that warning alerts are based

on an “aircraft’s relative position to a runway threshold and final approach course

centerline.”

The ARTS IIA MSAW system uses computer software that contains a terrain

database customized for the environment around each airport that utilizes ARTS

processors. The MSAW system is designed to visually and aurally alert a controller

whenever an IFR-tracked target with an altitude encoding transponder (Mode C) descends

below, or is predicted by the software to descend below, a predetermined safe altitude. The

ARTS IIA and EARTS MSAW systems use approach capture boxes aligned with runway

final approach courses to identify aircraft that are landing. Within these boxes, MSAW

applies special rules specific to approach and landing operations. The ARTS IIA

adaptation allows the use of a “pseudo-glideslope” that underlies the actual glideslope.

Predicted or actual descent below this pseudo-glideslope normally produces a low-altitude

alert. EARTS approach adaptation is less sophisticated and does not include glideslope

monitoring; instead, a single base altitude is used for the entire approach capture box.

According to FAA records, the Guam terminal (approach) MSAW system was

originally installed in 1990 to provide altitude protection within a 55-nm radius around the

Guam ASR-8 site. In March 1993, a new software package was developed and evaluated

49 See section 1.18.1.2 for information on Safety Board recommendations regarding the MSAW system. 
Factual Information 29 Aircraft Accident Report

by FAA technicians for installation at Guam. The new software was designed to inhibit

MSAW alerts inside a 54-nm radius of the Guam ASR-8 site. Thus, the MSAW was only

available (uninhibited) for a 1-mile radius (from 54 to 55 nm around the Guam ASR-8

site). According to FAA representatives, this change, designed as a temporary solution to

reduce false, or “nuisance,” warnings, was submitted by the Guam CERAP and approved

by the FAA’s Western Pacific Regional Office. The Safety Board requested documentation

of the reasons for the changes, but the FAA was unable to explain the specific reason(s)

for the change in the MSAW configuration.50 The FAA Technical Center in Atlantic City,

New Jersey, modified the software and delivered it to Guam in January 1994, but the

software did not become operational until February 1995. (The EARTS MSAW system at

Guam only generates visual MSAW alerts, and these alerts were not inhibited at the time

of the accident.)

The ARTS IIA system recorded no alerts for Korean Air flight 801 at any time.

The EARTS MSAW alert records showed that a visual approach path warning was

generated at 0142:20, about 6 seconds before the crash of flight 801, and continued until at

least 0142:49.

At the Safety Board’s public hearing,51 the FAA’s Deputy Program Director of Air

Traffic Operations testified that, in some circumstances, controller issuance of an MSAWbased safety alert could be a first-priority duty equal to separation of aircraft. FAA

Technical Center management testified that MSAW is a safety-critical service.

An FAA quality assurance evaluation report, dated July 31, 1995, on the Guam

CERAP facility stated that the MSAW system had been inhibited and that a NOTAM had

been issued about the inhibited MSAW.52 An FAA representative stated that, because no

“established policy” existed for MSAW operations at the time of the 1995 evaluation, the

MSAW inhibition was noted only as an “informational” item in the evaluation team’s

report and, as a result, did not require corrective or follow-up action. The report also

indicated that a new digital terrain map had been ordered and was scheduled for delivery

in April 1995 but that the delivery date had been rescheduled for August 1995.

50 According to FAA Order 7210.3M, “Facility Operation and Administration,” section 13-2-7, MSAW

and conflict alert functions can be temporarily inhibited “when their continued use would adversely impact

operational priorities.” The order also states that a brief written report should be sent to the FAA air traffic

directorate whenever these functions are inhibited.

51 The Safety Board may hold a public hearing as part of its investigation into certain accidents to

supplement the factual record of an accident investigation. The Board calls technical experts as witnesses to

testify, and Board investigative staff and designated representatives from the parties to the investigation ask

questions to glean factual information. The hearing is not intended to analyze any factual information for

cause. The Board held a public hearing on this accident from March 24 to 26, 1998, in Honolulu, Hawaii

(see appendix A). Five issues were addressed at this hearing: controlled flight into terrain (CFIT) accidents,

operation of navigational devices at the Guam airport, MSAW systems and practices related to these

systems, search and rescue operations, and U.S. and foreign government oversight of foreign air carriers

operating into the United States. 

52 Safety Board investigators and FAA representatives were not able to locate a NOTAM addressing the

Guam MSAW system’s inhibited status. However, the FAA stated that a NOTAM would not normally be

issued for an inhibited MSAW system.
Factual Information 30 Aircraft Accident Report

FAA documents revealed that new MSAW software became operational in April

1996, but it contained the same 54-nm-radius inhibition as the February 1995 version.

About 1 year after the installation of the new software, the FAA conducted another facility

quality assurance evaluation of the Guam CERAP. The evaluation report, dated April

1997, did not note that the ARTS IIA MSAW system remained inhibited. 

According to the FAA, the MSAW system at Guam was restored to full,

uninhibited operation on August 23, 1997 (17 days after the flight 801 accident), after the

monitoring software parameters were adjusted to reduce false alert incidents.53 The FAA

indicated that, since that time, controllers had been experiencing about 18 nuisance alarms

per day and that work was ongoing to reduce these alarms. 

1.10.1.3 Air Traffic Control Tower

The Agana tower is responsible for operations within the surrounding Class D

airspace, which is defined as the airspace within a 5-statute mile radius from the center of

the Guam International Airport up to, but not including, 2,500 feet agl. The tower facility

is located on the south-southwest side of the airport and is operational 24 hours a day. The

controller positions are arranged in a semicircular pattern that face generally from the

southwest to the northeast. The four operational positions are the controller-in-charge,

local control, ground control, and flight data. All of the positions are typically worked by

one controller as a combined function, but the positions may be separated depending on

traffic conditions and staffing levels.

In August 1994, Barton ATC International, Inc., was awarded the contract to

provide ATC services at the Agana tower. Barton was purchased by Serco Aviation

Services, Inc., in January 1997. According to a Serco official, 6 controllers with an

average of 15 years of experience worked at the tower at the time of the accident.54 Three

of these staff members, including the Air Traffic Manager, had worked at the facility when

it was operated by the U.S. Navy.

The Guam Air Traffic Manager said that the FAA evaluated the tower facility at

Guam in October 1995 to determine whether a new tower should be constructed or the

existing facility should be upgraded. The FAA also evaluated the Guam tower in

September 1996, and the Air Traffic Manager learned that the facility would be upgraded

with digital bright radar indicator tower equipment (D-BRITE) 55 displays. 

In February 1997, two D-BRITE systems were delivered to the Agana tower, and

the radar displays were installed by the FAA in July 1997. The tower controller on duty at

53 See section 1.18.1.1 for information on other postaccident MSAW-related actions taken by the FAA.

54 In July 1995 and April 1997, the FAA conducted standard evaluations of the Agana tower. In

addition, internal biannual evaluations were conducted during July 1995 and June 1997. After these

evaluations, labor hours were increased to provide dual coverage of ATC positions during peak traffic

periods. Because of this action, Serco began recruitment for an additional air traffic controller in mid-July

1997. The Safety Board was advised during its on-scene accident investigation that, although approval from

the FAA had not been received, an additional controller was hired on August 12, 1997.

55 D-BRITE is a radar display remote linked from approach control to the tower. 
Factual Information 31 Aircraft Accident Report

the time of the accident stated that the D-BRITE radar display was operational but had not

been certified for use. (At the time of the accident, the associated control panels for

configuring the Guam tower D-BRITE video maps and settings were located at the

Andersen AFB tower. According to the FAA, the equipment at the Agana tower was not

certified or commissioned for use because of missing hardware and computer software.)

The tower controller stated that the display showed secondary radar targets but that the

radar setting selected by the Andersen AFB controllers determined whether Mode C

targets would be displayed. He said that the controllers at Guam were not able to

determine an airplane’s position on the video map because it did not depict any final

approach courses or runway orientations for the airport.

By December 1997, the two D-BRITE systems had been tested, and the Agana

tower controllers received training on the systems’ operation. The D-BRITE systems were

certified and commissioned for use on April 11, 1998. The video map has been modified

to depict the airport with extended centerlines for both runways 6L and 6R, and the system

is controlled at the Guam tower.

The Agana tower controller on duty at the time of the accident told Safety Board

investigators that he arrived for duty about 2215 on August 5, 1997. After that time, he

and the controller on duty performed a position relief briefing, which covered airport

conditions, navigation aid conditions, traffic clearances that had been issued, and the

facility equipment status. After midnight, the controller performed daily administrative

duties. The controller said that he was working at the local control position, which was

located in the center of the tower cab facing the runway. The controller also stated that he

was aware of the NOTAM regarding the out-of-service glideslope.

The tower controller said that, when Korean Air flight 801 made initial radio

contact (about 0140:55), it was the only airplane that he was controlling. The tower

controller said that, when flight 801 did not visually appear within 3 to 4 minutes after the

airplane was cleared to land (about 0141:01), he commenced a communications search for

the aircraft.56 The controller attempted to contact flight 801 about 0145:13 and 0150:06.

Between about 0150:00 and 0151:00, the tower controller queried the CERAP controller,

the ramp controller, and an Andersen AFB controller about flight 801.

1.10.2 Instrument Landing System Ground-Based Equipment

FAA Form 6030-1, “Air Traffic Control Facility Maintenance Log,” for July 7,

1997, showed that the Agana tower had been notified by an FAA maintenance technician

that the glideslope portion of the ILS would be out of service starting that day for

extensive reconstruction. The reconstruction work included the replacement of the

glideslope’s equipment shelter and all cabling and the upgrade of the power systems and

grounding. A NOTAM issued by the FAA on July 7, 1997, indicated that the glideslope

would remain out of service until September 12, 1997. The complete ILS system was

56 FAA Order 7110.65, “Air Traffic Control,” paragraph 10-3-1(b), states that controllers are to declare,

in a timely manner, a flight that is overdue.
Factual Information 32 Aircraft Accident Report

flight checked, certified, and returned to service on August 31, 1997. The Safety Board’s

review of the facility maintenance log revealed no entries of pilot reports regarding the

ILS or related navigation systems from July 7 to August 6, 1997.

The accident airplane’s CVR recorded conversation among the flight crew

regarding the operational status of the ILS glideslope as they approached the airport. For

example, as previously stated in section 1.1, about 0139:55, the flight engineer asked, “is

the glideslope working? glideslope? yeh?” About 0139:56, the captain answered, “yes,

yes, it’s working.” About 0140:00, the first officer responded, “not useable.” About

0141:46, the captain asked, “isn’t glideslope working?”

In a postaccident interview, the captain of a Continental Air Micronesia 727-200

stated that, about 1530 on August 5, 1997, he was conducting an in-flight functional test of

a newly installed global positioning system (GPS)57 when the airplane’s instrumentation

showed an indication of the ILS glideslope,58 even though the glideslope was out of service.

Specifically, the captain stated that he was on approach to runway 6L at Guam International

Airport and was centered on the localizer when he noticed that the glideslope was also

centered and that no warning flags were associated with the ILS. In addition, the captain

said that the glideslope always indicated “center” with no warnings even when the airplane

was above the normal glidepath. The first officer confirmed the captain’s observations.

However, the flight crew did not indicate any anomalous glideslope indication to ATC

personnel or submit any maintenance writeups containing such information.

The Continental Micronesia captain told Safety Board investigators that he

originally assumed that the anomalous glideslope indication he experienced was caused

by an airplane anomaly. The captain further stated that he thought the anomaly might have

been a result of the GPS wiring installation. The captain did not report the glideslope

anomaly to his chief pilot until 2 days after the Korean Air accident. The first officer

stated that he and the captain “never thought twice” about the glideslope indications

because they knew the glideslope was inoperative.

According to the maintenance records for the Continental Air Micronesia airplane,

the first officer’s ADI and HSI were removed and replaced on August 5, 1997, after the

functional test flight. In addition, the records showed repeated squawks for the first

officer’s ADI and HSI between August 8 and 25, 1997. 

1.10.3 Instrument Approach Procedures at 

Guam International Airport

Instrument approaches available for runway 6L at the time of the accident were the

ILS (localizer only, glideslope out of service), the VOR/DME, and the VOR. 

57 A GPS is a navigation system that provides precise, real-time information about an airplane’s

position. 

58 The 727-200 was equipped with Rockwell International/Collins Model 51RV-1 ILS receivers.
Factual Information 33 Aircraft Accident Report

1.10.3.1 The Nonprecision Runway 6L Instrument Landing System 

Localizer-only (Glideslope Out) Procedure

The execution of the Guam ILS runway 6L localizer-only (glideslope out)

approach requires the use of the NIMITZ VOR as a step-down fix59 between the final

approach fix (FAF) and the runway and DME to identify the step-down points.60 The

DME is not colocated or frequency paired with the localizer transmitter (which is

physically located at the airport); rather, it is colocated and frequency paired with the

NIMITZ VOR. 

The nonprecision localizer-only approach requires the use of the localizer to obtain

lateral guidance to the runway, the DME to identify the step-down points, and the VOR to

identify the final step-down fix to the MDA. According to Jeppesen Sanderson’s

August 2, 1996, 11-1 ILS Runway 6L approach plate, the airplane should cross the FLAKE

initial approach fix (IAF)—located at 7 DME from the VOR—at or above 2,600 feet msl.

The nonprecision approach procedure prohibits descent below 2,000 feet msl (1,744 feet

above airport elevation) before reaching the outer marker identified as GUQQY, which is

the FAF and is located 1.6 DME from the VOR. Upon crossing the FAF, the procedure

prohibits descent below 1,440 feet msl (1,184 feet above airport elevation) until passing the

VOR. The procedure calls for a descent to 560 feet msl (the MDA, 304 feet above airport

elevation), and the pilot is required to count up from less than 1 DME, as the airplane

passes over the VOR, to 2.8 DME, the published missed approach point (MAP) and

location of the middle marker. If a missed approach is not required, the airplane can

continue its descent to the runway 6L threshold, located 3.3 DME from the VOR.

According to the FAA, the DME and localizer at Guam are now frequency paired

and colocated. In addition, the August 27, 1999, Jeppesen instrument chart for the ILS

runway 6L approach (which became effective on September 9, 1999) states “DME or

RADAR required” and includes “ILS DME” in the frequency box. 

1.10.3.2 Instrument Approach Charts for Guam International Airport

During postaccident examination of the cockpit area (which had separated from

the main wreckage, as discussed in section 1.12), investigators found a clear plastic

sleeve, measuring approximately 8 1⁄2 by 11 inches, that contained the following Jeppesen

approach charts for Guam International Airport, all of which were dated January 19, 1996:

11-1, ILS Runway 6L; 13-1, VOR Runway 6L; 13-2, VOR DME Runway 6L; 16-1, NDB

Runway 6L; and 16-2, NDB DME Runway 24R.61

59 The Safety Board is not aware of any other approaches that use a VOR as a step-down fix on the final

approach segment of a localizer-only approach.

60 The step-down approach technique requires pilots to cross specific navigational fixes at or above

several altitudes while descending to the MDA, at which point the pilot either executes a landing or a missed

approach. 

61 Copies of these approach charts are contained in the Safety Board’s public docket for this accident.

The Board maintains a public docket for each accident it investigates. The docket is used to establish the

permanent record of an accident.
Factual Information 34 Aircraft Accident Report

Charts 11-1 and 13-2 were found side by side and were visible through one face of

the plastic sleeve. Chart 16-1 and the blank side of an approach plate were visible through

the opposite face of the plastic sleeve. Chart 11-1, which is shown in figure 7, had the

following items highlighted with a green fluorescent tint: 62

Plan view

ILS facilities box: 063° (inbound magnetic course), 110.3 (ILS frequency), IGUM

(identifier), and FLAKE (IAF).

VOR facilities box: 115.3 (NIMITZ VOR frequency) and UNZ (identifier).

Profile view

2500’ (msl altitude crossing FLAKE).

1900’ (msl altitude crossing the outer marker).

256’ (touchdown zone elevation–runway 6L).

The instrument approach charts for Guam International Airport in effect at the time

of the accident were issued on August 2, 1996 (with an effective date of August 15, 1996).

Changes incorporated in the August 2, 1996, 11-1, ILS runway 6L approach chart (shown

in figure 1) included the location names, crossing altitudes, and the missed approach

procedure. Table 2 details the specific differences between the January and August 1996

instrument approach charts. 

1.11 Flight Recorders

1.11.1 Flight Data Recorder

The accident airplane was equipped with a Sundstrand Data Corporation model

573A FDR, serial number 2663, which was configured to record 51 parameters. The FDR

recorded information digitally on four tracks using 1⁄4-inch-wide magnetic tape that had a

recording duration of 25 hours before the oldest data were overwritten. Even though the

FDR case was damaged by impact forces, data could be retrieved and analyzed.

Examination of the data indicated that the FDR had operated normally, except for a loss of

synchronization about 3 seconds before the transition to 25-hour-old data. About 3 hours

48 minutes of data were transcribed for the entire accident flight (takeoff to impact).

After an initial readout of the FDR, Korean Air provided the Safety Board with

documentation that indicated that 11 additional sensors had been retrofitted after the

airline took delivery of the airplane. These retrofitted sensors—exhaust gas temperature

and oil quantities for the airplane’s four engines, static air pressure, and the left No. 4 and

right No. 12 spoiler positions—were not reflected in the FDR documentation provided by

the manufacturer or the airline at the time of the initial FDR readout. Documentation for

the additional sensors provided by Korean Air did not include the equations necessary to

62 The plan view is the approach viewed from above; the profile view is the approach viewed from the side.
Factual Information 35 Aircraft Accident Report

Figure 7. The January 19, 1996, 11-1 ILS runway 6L instrument approach chart.

Reproduced with the permission of Jeppesen Sanderson, Inc. NOT TO BE USED FOR NAVIGATION.
Factual Information 36 Aircraft Accident Report

Table 2. Information differences between the January 19 and August 2, 1996, Guam ILS 

runway 6L approach charts.

Chart dated January 19, 1996 Chart dated August 2, 1996

No note regarding DME requirement. Note on chart stating DME REQUIRED. DME from 

UNZ VOR.

MILITARY (in amendment block). AMEND 0 (in amendment block).

HAMAL (IAF) is 8 DME on R-343. HAMAL (IAF) is 7 DME on R-343.

ZEEKE (IAF) defined as 7 DME on R-169. ZEEKE defined as 7 DME on R-169.

FLAKE (IAF) defined as 7 DME on R-242. IAF is defined as 7 DME from UNZ on the 

localizer.

FLAKE (IAF) crossing altitude is 2,500 feet. 7 DME fix (IAF) on the localizer; crossing altitude 

is 2,600 feet.

Outer marker fix designated OM. Outer marker fix designated GUQQY.

Outer marker crossing altitude is 1,900 feet. GUQQY crossing altitude is 2,000 feet.

VOR crossing altitude is 1,300 feet. VOR crossing altitude is 1,440 feet.

Missed approach point designated 2.8 DME at the 

middle marker.

Missed approach point depicted in large, bold font: 

D2.8 UNZ VOR, MM

Touchdown zone elevation for runway 6L. Touchdown zone elevation for both runways 6R 

and 6L.

Sidestep minimums included. Sidestep minimums deleted.

Missed approach procedure: Climb to 2500’

outbound on UNZ VOR R-062, turn RIGHT direct 

FLAKE D7.0.

Missed approach procedure: Climb to 2600, then 

turn RIGHT via UNZ VOR R-242 to FLAKE D7.0 

UNZ VOR and hold SOUTHWEST, RIGHT turn, 

062° inbound.

Holding pattern at FLAKE depicted. No holding pattern at the IAF or FLAKE depicted.

No obstruction symbol depicted at the VOR. 724-foot obstruction symbol depicted at the VOR.

803-foot elevation shown for UNZ VOR. No elevation shown for UNZ VOR.

1,154-foot elevation at outer marker. 1,190-foot obstruction shown at GUQQY.

1.6 DME at outer marker depicted on plan view. 1.6 DME UNZ VOR at GUQQY depicted on plan 

view.

No note for FLAKE. Note added: (FLAKE) for missed approach only.
Factual Information 37 Aircraft Accident Report

convert the recorded information into engineering units.63 The Safety Board applied

equations used in previous readouts of FDRs from similar 747s, but the validity of the

conversion equations could not be verified.

1.11.2 Cockpit Voice Recorder

The accident airplane was equipped with Fairchild model A-100A CVR, serial

number 61216. The CVR case revealed no evidence of structural damage, and the interior

of the recorder and the tape showed no evidence of interior heat or impact damage. The

recording consisted of four channels of “good quality” audio information,64 which

included the captain, first officer, and flight engineer microphones; audio panels; and the

cockpit area microphone. The fourth channel also recorded the interphone and the public

address system. 

The audio portion began about 0111:42 and continued uninterrupted until

0142:32.53. The recording ended shortly after the airplane crashed and the power to the

CVR was lost. The CVR group, consisting of representatives from the parties to the

investigation and the KCAB, collectively transcribed the 31-minute 1-second tape in its

entirety. A bilingual (English and Korean) transcript was produced of the entire recording

(see appendix B).

1.12 Wreckage and Impact Information

1.12.1 General Wreckage Description

Examination of the ground scars and the debris pattern revealed that the accident

airplane impacted high terrain with the left outboard engine, main landing gear, and left wing

at an elevation of about 660 feet msl and on a magnetic heading of approximately 063°.

The Safety Board performed a complete survey of the accident site and airplane

structure. The main wreckage site area was in a gully covered with dense vegetation,

located approximately 2,000 feet southwest of the NIMITZ VOR. The wreckage

distribution area was about 2,100 feet long and 400 feet wide and included airplane debris,

tree strikes, and ground impact marks. All major structural components of the airplane and

control surfaces that were not consumed by the postimpact fire were identified along the

wreckage path. The terrain along the wreckage path was hilly and ranged from about

673 feet msl at the first tree strikes to about 582 feet msl at the main wreckage area. 

63 See section 1.18.7.1 for safety recommendations regarding the need for improved FDR

documentation.

64 The Safety Board ranks the quality of CVR recordings in five categories: excellent, good, fair, poor,

and unusable. For a recording to be considered “good quality,” most of the crew conversations need to be

accurately and easily understood. The transcript developed from the recording might indicate several words

or phrases that were not intelligible; such losses are attributed to minor technical deficiencies/momentary

dropouts in the recording system or simultaneous cockpit/radio transmissions that obscure one another.
Factual Information 38 Aircraft Accident Report

The initial point of impact was evidenced by several cut treetops that extended

along the wreckage path. Several ground impact marks, consistent with the main landing

gear, were found in the vicinity of the broken oil pipeline, located about 400 feet from the

point of initial impact. A ground scar, about 89 feet long, 6 feet wide, and 2 feet deep, was

found about 415 feet from the point of initial impact, and several pieces of the No. 1

engine cowl were found embedded in this area, along with parts of the left wing leading

and trailing edge flap structure.

Numerous parts of the left main landing gear, including two wheels and tires, were

found embedded in a small berm about 1,430 feet from the initial impact point. Most of

the fuselage structure was located in the main wreckage area and was found separated into

five major sections: the empennage, the aft fuselage, the center fuselage, the forward

fuselage, and the cockpit. 

Figures 8a and 8b are photographs of the wreckage from Korean Air flight 801.

Figure 8a shows the airplane wreckage in relation to runway 6L, the NIMITZ VOR, and

Apra Harbor.65 Figure 8b provides a closer view of the wreckage and the VOR. 

Figure 8a. Wreckage from Korean Air flight 801 in relation to Guam International Airport 

runway 6L (upper middle), the NIMITZ VOR (upper right), and Apra Harbor 

(upper left).

65 Apra Harbor is located 5 DME on the approach course.
Factual Information 39 Aircraft Accident Report

1.12.2 Fuselage and Empennage

The cockpit section was located down an embankment beyond the large portion of

the forward fuselage. The airplane’s VHF [very high frequency] navigational radio control

panels were recovered from the wreckage. To determine which radio frequencies were

selected on both the captain’s and the first officer’s control panels in the cockpit, an

examination was conducted on October 2, 1997, under the Safety Board’s supervision, at

Pacific Aero Tech, an FAA-approved repair station for the control panel, in Kent,

Washington. The captain’s frequency selector was found tuned to 110.30 megahertz

(MHz), which was the Guam localizer frequency. The captain’s control panel had been

damaged by impact forces, and the frequency depicted was locked into a position that

could not be changed by turning the frequency selector knob. The first officer’s control

panel selector knob could be easily rotated, and the frequency selector was found tuned to

116.60 MHz, which did not correspond to any voice or navigation frequencies at Guam. 

The cockpit section was found separated about station66 400. Most of the aft nose

wheel well structure (nose gear attachment point) was relatively intact with the trunnion

Figure 8b. Closer view of the wreckage from Korean Air flight 801 and the NIMITZ VOR.

66 Station refers to a specific location on the airplane, as measured from a data point. Examples include

fuselage station, typically measured from a point forward of the nose of the aircraft, and wing station,

typically measured from a point at the wing root and extending outward.
Factual Information 40 Aircraft Accident Report

support fittings, drag brace fittings, and transverse beam still attached. Examination of the

nose landing gear and the wing- and body-mounted landing gear revealed that they were

in the extended position at the time of impact. This section of fuselage structure revealed

no evidence of fire damage. 

The forward fuselage section approximately from stations 400 to 1120 was located

on the upslope of a hill beyond the center fuselage section. The fuselage structure was split

above the main deck floor on the right side, and most of the internal structure (frames,

stringers, and fractured floor beams) remained attached. The structure exhibited extensive

fire damage, including burn-through of the crown area (upper forward fuselage),

sidewalls, and floor. 

Examination of doors 1L, 1R, 2L, and 2R could not be performed in detail because

the airframe structure around these doors was heavily burned, and only portions of the

doors were located in the main wreckage site. The door identified as 3L was found closed

and locked. Door 3R was found separated from the fuselage, with more than one-half of the

door frame area missing because of fuselage separation in this area. According to Korean

Air records, the 3L and 3R doors were deactivated before the company took delivery of the

airplane. The doors identified as 4L and 4R were found detached from their respective

mounted positions, and approximately one-third of the 4R door frame was missing. Door

5L was found closed and locked. Door 5R was found in the open position; however, the

door handle was not in the full open position. The upper deck doors were not located; these

doors were mounted in an area of the fuselage that sustained extensive fire damage. 

The center portion of the fuselage structure, extending from stations 1120 (left

side) to 1240 (right ride) and aft to station 1780, was found attached across the crown area

and to the right wing by the landing gear beam. The landing gear beam at station 1350 was

attached to the fuselage section. The entire center section was found rotated about 180° to

the debris path, with the forward end of the section facing the aft body and empennage.

The interior was extensively damaged by fire throughout the section. The exterior fuselage

skin bore fire damage primarily adjacent to the break, and the right-side fuselage skin was

heavily burned between doors 3R and 4R.

The exterior fuselage surface was lightly sooted on the left side of the center

section, and the exterior of the right side bore evidence of light soot and areas of fire

damage around the periphery of door 5R. The interior was damaged by fire from the main

deck floor level to the belly; however, the upper portions of the internal structure were not

burned significantly. The aft pressure bulkhead was intact, with the lower portion

deformed. The bulkhead was not damaged by fire.

The empennage was found separated from the aft fuselage in an upright position.

The empennage had sustained impact damage and some light fire damage. The left- and

right-side horizontal stabilizers, their respective elevators, and the vertical fin (with the

rudder attached) remained attached in their respective mounted positions.
Factual Information 41 Aircraft Accident Report

1.12.3 Wings

The left and right wings were located on the left side of the airplane in the main

wreckage area. The right wing remained attached to the fuselage center section, and the

left wing was located under the fuselage and right wing.

The outboard section of the left wing was located approximately parallel to and

under the right wing section. This portion of the left wing structure was approximately

80 percent intact and had sustained extensive postimpact fire damage to the upper skin and

midspar (between wing stations 470 and 1200), including the midspar web and chord

structure. The corresponding lower skin and stringers also exhibited considerable fire

damage. Exposure to the postimpact fire resulted in various degrees of damage to the

remaining wing structure, including the leading edge and trailing edge flap structure. The

outboard wing tip, which comprised 10 composite aluminum and fiberglass structures,

was found separated from the wing box at the surge tank end rib at wing station 1548 and

was not damaged by fire.

Most of the right wing inboard and outboard trailing edge flaps and support

structure were found intact and attached to the wing box, except for approximately 6 feet

of the inboard fore, mid, and aft flap structure of the inboard-most section of the flap. This

section had separated and was found in the debris path in the vicinity of the initial impact

point. Examination of the ball screw indicated the flap extension was approximately 25°.

All of the leading edge variable camber flap and inboard Krueger flap structure

was destroyed by impact forces and the postcrash fire. The trailing edge flaps and control

surfaces were found relatively intact with some localized fire damage, except for the

inboard flap system, No. 4 flap track, and No. 6 spoiler, which separated from the wing

box during initial impact.

The No. 1 through No. 5 flight spoilers were found in place in a neutral position at

the in-spar box structure. The spoilers exhibited extensive fire damage. The No. 6 ground

spoiler had separated from the wing and could not be located among the wreckage.

Examination of the spoiler support beam revealed evidence consistent with overload from

impact forces. 

The full combination of outboard flap and support structure on the left wing was

found in place on the wing box with a detent extension indicative of approximately 25°.

All of the inboard flap and most of the support structure had separated from the wing box

and was found along the wreckage path, with numerous parts in the area of the initial

impact point.

1.12.4 Engines

All four of the engines were found separated from their respective mounted

positions on the airplane. The No. 1 engine was located about 970 feet from the initial
Factual Information 42 Aircraft Accident Report

impact point and about 1,300 feet from the main wreckage site. The other three engines

were all located within the main wreckage site. 

All of the engines sustained damage to the fan blades, with the tips and leading

edges bent opposite to the direction of rotation. Further, vegetation and dirt had been

ingested into the fans and low-pressure compressors of each of the engines. Examination

of the rotating parts within each engine revealed evidence of rotational smearing, rubbing,

and blade fractures that were consistent with the engines producing power at the time of

impact. Further, none of the four engines exhibited any evidence of uncontained failures,

case ruptures, or in-flight fires. All of the thrust reverser actuators that were found

indicated that the thrust reversers on each of the engines were in the stowed position.

1.13 Medical and Pathological Information

Tissue and fluid samples from both pilots and the flight engineer were transported

to the FAA’s Civil Aeromedical Institute (CAMI) for toxicology analysis. The CAMI

laboratory performed its routine analysis for major drugs of abuse and prescription and

over-the-counter medications, and the results were negative. The analysis detected ethanol

in the blood and tissue samples of both pilots and the flight engineer, but no ethanol was

detected in the vitreous (eyeball) fluid sample taken from the captain. All specimens were

noted in the laboratory report to have been received by CAMI in a “putrefied” condition. 

According to the captain’s medical records, he consulted a personal physician on

July 27, 1997, and was diagnosed with bronchitis. The physician prescribed three

medications: Copan (clenbuterol), a medication to open the upper airways; Vibramycin

(doxycycline), an antibiotic; and Sentil (clobazam), a medication in the benzodiazepine

class of drugs that is frequently used as a sedative.67 The postmortem tests conducted by

CAMI on the captain’s blood specimen were negative for benzodiazepines, and no CAMI

testing was available for the detection of Copan or Vibramycin.

The remains of deceased airplane occupants were examined by the Disaster

Mortuary of Guam to determine the cause of death. Because many of the remains were

fragmentary, the total number of remains sets (300) exceeded the number of accident

fatalities. Autopsy examinations and toxicological analysis determined that the airplane

occupants died of blunt force trauma, thermal injuries, and carbon monoxide inhalation.

Complete autopsies and toxicological evaluations were performed on the remains of the

three flight crewmembers (as discussed previously.) Of the 297 non-flight crewmember

67 The captain did not advise Korean Air, before the July 28 to July 30, 1997, round trip flight from

Seoul to San Francisco that he had been diagnosed with bronchitis and prescribed medications for the

condition, nor did he receive medical approval from the company to conduct this trip. Korean Air’s

Operations Manual, chapter 4-12-4 (dated May 21, 1997), requires that a crewmember who “must be on

duty under influence of medication, shall follow the direction of an Aeromedical Specialist.” International

Civil Aviation Organization (ICAO) Annex 1, section 1.2.6 (dated November 16, 1989), specifies that

license holders should not exercise the privileges of their licenses and related ratings at any time when they

are aware of any decrease in their medical fitness that might render them unable to safely exercise these

privileges.
Factual Information 43 Aircraft Accident Report

sets of remains, about 145 sets could not be evaluated for soot in the airway because the

condition of the remains precluded an evaluation. Of the 137 remains sets that could be

evaluated, soot was found in the airway of 20 sets, no evidence of soot was found in

41 sets, and no definitive observations could be made regarding soot in the airway for

76 sets (in many of these 76 cases, however, the traumatic injuries described would have

precluded survival after the impact sequence). Information was not available for the final

15 sets of remains.

1.14 Fire

A fire erupted during the impact sequence and was sustained by the fuel on board

the airplane; the last report of small remaining fires was about 0800. The Safety Board’s

investigation revealed no evidence of an in-flight fire.

1.15 Survival Aspects

1.15.1 General

The 747-300 cabin contained a total of 385 passenger seats and was divided into

three sections: first class, prestige (business) class, and economy class. The airplane was

configured with four rear-facing, double-occupancy flight attendant jumpseats and six

rear-facing, single-occupancy flight attendant jumpseats, all of which were equipped with

a four-point restraint system. The flight attendant seats were located at each of the four

emergency exit doors located on the left and right side of the cabin.

Of the 237 passengers aboard flight 801, 3 were children between 2 and 12 years

old, and 3 were children 24 months or younger. Thirty-one airplane occupants were found

alive by rescue workers Two passengers died en route to area hospitals. The autopsy report

for one of these two passengers did not identify a single cause of death (her remains

showed evidence of multiple internal injuries but no burns or soot in her airway). The

autopsy report, however, identified that she was alive when medical personnel arrived at

the accident scene and that she was treated aggressively as a result of serious injuries. In

addition, 3 passengers died of their injuries within 30 days after the accident, bringing the

official total number of accident survivors to 26. 

Of the 26 survivors of the accident, 7 passengers and 1 flight attendant were seated

in the first class section, 1 flight attendant was seated in the prestige class section,

7 passengers were seated in the forward economy class section, and 9 passengers and

1 flight attendant were seated in the aft economy class section. Two of the surviving flight

attendants and 13 of the surviving passengers were seated on the right side of the airplane;

6 of these 13 passengers were seated over the right wing. Figure 9 shows the 747-300

cabin configuration and the survivor seat locations.
Factual Information 44 Aircraft Accident Report

Figure 9. Korean Air flight 801 cabin configuration and survivor seat locations.
Factual Information 45 Aircraft Accident Report

1.15.2 Survivor Statements

Safety Board investigators and MOCT officials interviewed a surviving flight

attendant and several passengers in a Guam hospital on August 9, 1997. In addition,

11 passengers responded to a Safety Board “Survivor Questionnaire” after returning to

Korea. Information obtained from the interviews and questionnaire responses indicated that

these survivors either had been ejected from the airplane during the impact sequence or had

extricated themselves from the wreckage. Most of these survivors indicated that they were

injured as a result of the impact; however, two survivors stated that they were injured by

fire. Further, the survivors stated that, during their egress from the airplane, they

encountered damaged seats, overhead bins that had fallen, and other unidentified obstacles.

A flight attendant who was seated in the R1 jumpseat (in the first class section)

stated that she heard a loud “boom” before the airplane began shaking violently and

breaking up. The flight attendant said that she was thrown from the airplane in her

jumpseat during the impact. She then unfastened her restraint system, walked about

30 feet beyond the right side of the airplane, and assisted a female passenger.

Several surviving passengers stated that, after the impact, baggage from the

overhead bins fell to the floor and that “intense flames and heat swept through the cabin.”

One survivor, who was seated in the aft economy class section (row 34), stated that her

husband was engulfed by fire in the seat next to hers. Another passenger, a professional

helicopter pilot, stated he felt what he thought was a “hard landing” but that the airplane

then rolled and began to disintegrate. The passenger stated that he exited the burning cabin

by walking through a large hole in the fuselage. He also said that a “ball of flame was going

down the center of the airplane” and that passengers were screaming and calling for help.

1.15.3 Emergency Response

About 0150, the Guam Fire Department (GFD) communications center received

an emergency call from a local resident, who reported seeing a fire in the hills near the

airport. About 0158, after receiving notification of the accident from the CERAP

controller (based on the Ryan International flight crew’s observation of a “big fireball on

the hillside”), the Agana tower controller alerted ramp control about the crash of Korean

Air flight 801.68 According to airport ramp control logs, ramp control initiated the required

emergency notifications at 0202, including a call at 0208 to the Naval Regional Medical

Center to place its personnel on standby. According to GFD communications center logs,

notification of a downed aircraft was received from the Guam ramp control at 0207.

Immediately afterward, the GFD communications center dispatched Engine Company

No. 7, which was located about 3 1⁄2 miles from the accident site. According to the GFD

chief, the departure of Engine No. 7 was delayed because its brakes had been drained to

prevent an overnight buildup of condensation in the brake lines.69 Thus, the brake lines

had to be first recharged with air. Engine No. 7 departed the station at 0219 (12 minutes

68 According to the Guam airport emergency response guidelines, ramp control is responsible for

providing all communication/dispatch functions in the event of an emergency.
Factual Information 46 Aircraft Accident Report

after being notified) and arrived 15 minutes later (at 0234) at the gate to the pipeline/VOR

access road (which was the only vehicle ground access to the accident site).

The Federal Fire Department’s Station No. 5, located on Nimitz Hill 1 mile away

from the accident site, was the nearest fire station.70 GFD communications center logs

indicated that the federal dispatch facility was notified of the accident at 0207, but the

federal dispatch facility records indicated that notification was received at 0234 and that

Engine No. 5 arrived at the scene at 0239. 

The Chief of Staff, Commander, U.S. Naval Forces, Marianas, who was also the

wife of the airport director, testified during the public hearing that she first became aware

of the crash after an airport official called her husband at 0216 to report that a Korean Air

747 was missing over the Nimitz Hill area. The Chief of Staff went outside and observed a

“bright orange glow” in the sky. She then notified the Navy Security Office and Command

Duty Officer to activate the Navy’s “first responders,” search and rescue assets, and

hospital mass casualty units.

The GFD incident on-scene commander (OSC) told investigators that he arrived at

the accident site about 0234 and proceeded down the access road toward the wreckage.

The access road to the site—a narrow (one-lane) dirt and stone road with a drainage ditch

on both sides—had been blocked by a section of damaged oil pipe. The pipe, which was

located next to the road and elevated about 3 feet, was removed 1 hour later by a truckmounted winch after efforts to remove it by hand were unsuccessful. According to GFD

documents, Engine No. 7 became stuck in mud when the driver tried to maneuver around

the oil pipe obstruction. The GFD chief stated that, once the broken pipeline had been

removed and the fire truck had been towed out of the mud (about 0345), no further

blockages of the access road were reported.

In a postaccident interview and at the Safety Board’s public hearing, the OSC

testified that he and other rescue personnel abandoned their vehicles and approached the

accident site on foot. The OSC indicated that he and the rescue personnel carried

flashlights, rope, and a trauma kit. The OSC stated that he heard people screaming and

could see small areas of fire. The OSC said that the darkness and terrain made access to

the accident site difficult. 

The OSC stated, “we had to go across all types of vegetation, sword grass, all types

of trees...it was very rough getting down to the crash site, especially with no light

whatsoever but flashlight alone...we had to deal with all kinds of bugs down there,

snakes...we tried to pull out the survivors the best way we could and from what we

received in fire-fighting training.” The OSC also stated that 

69 After the accident, GFD policy was changed to drain fire truck brake lines only during periodic

maintenance to prevent moisture from contaminating the lines. The GFD chief stated that a fire truck would

not be taken out of service without having another vehicle in its place.

70 The Federal Fire Department’s Station No. 5 is responsible for providing fire protection to U.S. Naval

facilities on Guam.
Factual Information 47 Aircraft Accident Report

the airplane [had been] totally engulfed [in fire] when we got there...already to the

point where the fires weren’t really bothering the rescuers. The rescue personnel

were actually going into the plane checking passengers...who was still alive and

who was not.... We had to go back up on those slippery hills without any

rappelling gear whatsoever.... We were holding the victims in one arm and

holding the tools in the other so we just could make it to the top.... We did this

until we could clear a landing site for the choppers.... 

The OSC stated that a command post was established to the east (on higher terrain)

of the main wreckage site, where requests for resources and personnel were relayed by

radio to the GFD dispatcher. The dispatcher then relayed the information to the response

activity coordination team located at Guam Civil Defense (GCD) headquarters. 

The GCD director told Safety Board investigators that he arrived at the access road

gate about 0235. The director stated that the GCD owned a command post vehicle but that

he did not use the vehicle because it was outdated and had been out of service for several

years. He stated that funds were not available to repair and equip the vehicle.71

A U.S. Navy emergency medical technician (EMT) assigned to the Naval Regional

Medical Center told Safety Board investigators that he received verbal notification of the

accident between 0200 and 0230 from personnel at the Guam Naval Activities Station,

which is located about 8 miles southwest of Nimitz Hill. The EMT reported that he arrived

at the accident site on foot between 0245 and 0300. Upon arrival, the EMT observed the

fuselage and interior engulfed in “bright blue flames.” The EMT stated that he approached

the burning wreckage to within about 150 feet and saw about 14 survivors outside the

airplane with various injuries, most of which were burn related. The EMT said that many

of these survivors were clustered together and that they appeared to have extricated

themselves from the wreckage.

The EMT told investigators that it was difficult to maneuver around the wreckage

because of darkness, intermittent rain, soft ground, tall grass, and rugged terrain. Further,

the EMT stated that two triage areas had been set up: one near the front of the airplane

(near the nose section), and the other between the fuselage wreckage and the access road. 

A Guam Department of Public Health physician told Safety Board investigators

that she was notified of the accident by GCD about 0245 and arrived at the accident site

about 0315. Upon arrival, she noted that the triage and transportation activities were

“functioning well” but that medical and evacuation efforts lacked coordination.

Additionally, she said that, after assessing the situation, she established another triage area

near the VOR, where the terrain was level. 

Some of the survivors that had been treated at the triage area near the airplane were

evacuated by military helicopters, whereas others had been carried to the triage area near

the VOR to be treated and then transported by ambulance via the access road. The OSC

71 After the accident, the regional director of the Federal Emergency Management Agency stated that

the agency would provide money to refurbish the command post vehicle.
Factual Information 48 Aircraft Accident Report

stated that the first survivors were transported to hospitals between about 0300 and 0330.

The EMT stated that the last survivor was found about 0430. According to hospital

records, the first survivor transported by helicopter to the U.S. Naval Hospital arrived

about 0334, and the last survivor arrived by helicopter about 0710. Also, hospital records

indicated that the first survivor transported to Guam Memorial Hospital arrived by

ambulance about 0420 and that 16 other survivors were transported by ambulance to

Guam Memorial, the last of which was admitted about 0709.72

1.15.3.1 Emergency Response Planning and Exercises

At the Safety Board’s public hearing, the GCD director testified that, in April

1997, a joint full-scale disaster drill had been conducted on the airport with Guam airport

authorities.73 The GCD director stated that no off-airport drills had been conducted before

the accident but that an off-airport aircraft accident drill had been scheduled for September

1998. The GCD director added that, after the accident, new radios had been purchased to

allow interagency communication and coordination during emergencies.

The GCD director also testified that, before the accident, GCD authorities had a

memorandum of understanding (MOU) with the U.S. Air Force for emergency response

but had not established an MOU with the U.S. Navy or U.S. Coast Guard. The GCD

director stated that, after the accident, Guam authorities formed an emergency response

committee, which included the Navy, the Coast Guard, and the Air Force, and that an MOU

involving all emergency response agencies on the island had been drafted. The director

stated that the MOU called for emergency response drills involving all of the agencies. 

In June 1999, the GCD acting administrator stated that, instead of the MOU, a final

draft of “Joint Standard Operating Procedures for Mutual Civil Emergency Support for

Emergencies or Disasters Without Presidential Declaration” was circulated to the GCD

office; Commander, Naval Forces Marianas; U.S. Coast Guard Marianas Section; and the

U.S. Air Force 43rd Air Base Wing. The acting administrator indicated that the procedures

could be implemented by the end of June 1999. The Safety Board’s latest information from

the GCD office (August 1999) indicated that the procedures had not been implemented. 

Officials from the GCD office stated that the planned September 1998 off-airport

exercise did not take place. In June 1999, the GCD acting administrator stated that

planning for a major off-site exercise had started.

72 Admittance times may be different than arrival times because patients received immediate emergency

room treatment before being officially admitted to the hospital.

73 Title 14 CFR Section 139.325, “Airport Emergency Plan,” paragraph (g)(4) and (5), requires the

certificate holder, that is, the airport, to “at least once every 12 months, review the emergency plan with all

the parties with whom the plan is coordinated...ensure that all parties know their responsibilities...and hold

a full-scale airport emergency plan exercise at least once every three years....”
Factual Information 49 Aircraft Accident Report

1.15.4 Guam Governor’s Accident Response Review

The Guam government conducted a review of its response to the accident and

issued a report, titled Korean Air 801 Incident Report. According to the report, the “focus

of the investigation was to identify an accurate timeline of emergency response during the

first hours of the incident, and to address issues/questions raised concerning the rescue

efforts. Those issues/questions concerned fire suppression, command structure and

activity of key members of the rescue team.”

Problems discussed in the report included the lack of radio communications

between key personnel, which complicated the command situation. The report stated,

“...the civilian and military components were on different and incompatible radio

systems...radios had to be shared in the command post so that the various agencies could

communicate.”

Additionally, the report cited the remoteness of the accident site and the difficulty

in bringing fire trucks close enough to the site to be effective. However, the report stated

that “no fire suppression was used” because it would have “interfered with rescue

operations.”74 The report also cited accounts from rescuers that indicated, “...most of the

survivors were initially located away from the flames of the aircraft.... It is noted that the

first rescuers arrived approximately 55 minutes after the plane had crashed.... If the fire

was as intense as originally reported [immediately after impact], fatalities caused by fire

and smoke inhalation would have occurred before the rescuers arrived.” 

1.16 Tests and Research

1.16.1 Enhanced Ground Proximity Warning System Simulation

Because of advances in computer technology and terrain mapping capabilities,

GPWS manufacturers have developed improved terrain avoidance systems. In 1997, the

FAA certified a new terrain awareness and warning system (TAWS), also known as

enhanced GPWS. (See section 1.18.2.2 for general information about enhanced GPWS.)

This system was not installed or required on the accident airplane.75

An enhanced GPWS simulation was conducted after the accident to determine the

additional forewarning that the flight crew of Korean Air flight 801 would have received

if such a system had been installed on the airplane. The simulation revealed that the flight

crew would have received an aural “CAUTION TERRAIN” warning and a yellow visual

terrain depiction on the weather radar about 60 seconds before impact. In addition,

74 The report stated that water and foam were available on the fire trucks at the scene but that “water

would have spread...fire caused by fuel” and “foam would have caused further injury to those with burns

and/or open wounds.” The report also added that airborne water buckets would have pushed the toxic gases

and smoke onto rescuers.

75 At the time of the accident, no enhanced GPWS system had been certified for the 747-300 series

airplane.
Factual Information 50 Aircraft Accident Report

enhanced GPWS would have provided the aural annunciations “TERRAIN, TERRAIN”

and “PULL UP” and a red visual terrain indication on the weather radar display about

45 seconds before impact; the annunciations would have sounded continuously until

completion of a successful escape or impact with terrain.

In July 1999, Korean Air announced that it would equip all of its aircraft with

enhanced GPWS by the end of 2003. The KCAB subsequently confirmed Korean Air’s

announcement. 

1.16.2 Minimum Safe Altitude Warning System Simulation

An ARTS IIA MSAW simulation was conducted after the accident at the FAA

Technical Center in Atlantic City, New Jersey. The simulation indicated that, without the

54-nm-inhibited ring, a visual and aural low-altitude alert would have been generated for

flight 801 on the terminal ARTS IIA display at the CERAP facility. Further, the simulation

indicated that the visual and aural approach path alert would have been generated at

0141:22, as the airplane was descending through 1,700 feet msl, or about 64 seconds

before the airplane crashed. 

1.16.3 Korean Air Spurious Radio Signal Tests

After the accident, the KCAB and Korean Air conducted a series of independent

tests on a Boeing 747 on the ground to determine if spurious radio-frequency energy could

induce an abnormal (“false”) glideslope indication. These tests were not intended to

represent conditions at the time of the accident; rather, the tests were designed to explore

ILS system sensitivity to spurious signals. According to Korean Air engineers, the tests

revealed that the glideslope deviation needle could be positioned near the middle of the

glideslope reference scale, and the warning flag could be retracted by introducing a “335

MHz signal (120 Hz signal modulated at 100 percent)” near the ILS receiver antenna.76

The KCAB and Korean Air technical staff demonstrated their test results to the

Safety Board and parties to the investigation at a January 1998 meeting. The

demonstration, which was conducted using a portable 51-RV5(B) receiver and a signal

generator, indicated that a single 120-Hz signal with 100-percent modulation at the Guam

ILS frequency resulted in an out-of-view glideslope flag and glideslope indicator

movement.

If a glideslope signal is not being generated by the transmitter (resulting in an open

frequency channel/band), the airborne glideslope receiver will continue to hunt for a

glideslope signal. Although the radio-frequency filters built into the receivers are designed

to bias out the majority of spurious radio signals, the postaccident testing by the KCAB

and Korean Air revealed that, in the absence of a valid glideslope signal, it is possible for

an airborne glideslope receiver to momentarily receive a spurious signal in the frequency

76 See Public Hearing exhibit 9F for detailed information regarding these spurious signal tests.
Factual Information 51 Aircraft Accident Report

band of the glideslope signal. The reception of such a signal could result in the movement

of the glideslope receiver needle and present a false indication to the pilot. 

1.16.3.1 Guam Instrument Landing System and Potential Interference 

From Spurious Radio Signals

An FAA National Resource Engineer for Navigation testified at the Safety Board’s

public hearing about the Guam ILS system and the potential for interference from

spurious radio signals. The engineer stated that “the pilot would normally be warned that a

signal is not present by the presence of a flag, a warning flag, that indicates that something

about the receiver system or something about the ground system is abnormal....” The

engineer testified that he assumed that the accident flight crew’s remarks regarding the

glideslope (as recorded on the CVR) had to do with the presence or absence of flags. He

concluded that “...there must have been some sort of flag activity coming into view,

disappearing from view, some time during the approach” and that the comments, although

they did not convey information about the duration of any flag activity, indicated that

“...there must have been enough absence of the flag for the crew to occasionally decide

that the system was on the air when in fact it wasn’t....” 

The FAA engineer also testified that, although the glideslope at Guam

International Airport had been removed from its shelter, radio signals generated by some

other source could have provided an intermittent signal to the glideslope receiver, which

might have prevented the instrument warning flag from remaining in view. The engineer

explained that potential external sources of noise and unintended signals, which are

normally too weak to be heard, can be heard on an empty channel and that, during

airborne flight tests of ILSs in which the localizer or the glideslope is turned off, it has

been fairly common for the cockpit instrumentation to record intermittent indications of

flag and needle activity. However, he expressed that this sort of activity on the

instrumentation (referred to by pilots as “flag pops”) is typically intermittent and of very

short duration. 

The engineer testified about the types of radio signals that could potentially cause

a movement of the flag. He stated that the ILS transmits two tones and that the difference

in the signal strength of the tones deflects the glideslope fly-up and fly-down needle. The

engineer indicated that the receiver has some circuits that look for these two tones and that

the fly-up/fly-down needle indicates the difference in strength of those two tones. He

added that “...the difference will be zero, and the needle will be centered when the two

tones are equal....” 

Further, the FAA engineer stated that the flag circuit, the other indication that a

pilot sees, is driven by a signal that is the sum of the two circuits or the two signals. He

indicated that “as long as the 90 and 150 [Hz] signals are both present at sufficient

strength, the flag will remain out of view.” The engineer also stated that, if there is no

ground station transmitting and no intended ground station but some other signal, then

those portions of the signal that contain 90- and 150-Hz tones77 would still get through

those filters and could cause the needles to deflect. The engineer added that, depending on
Factual Information 52 Aircraft Accident Report

the shape of the filters’ response (which varies according to receiver model and

manufacturer), the circuits would experience varying amounts of intermittent deflections. 

1.17 Organizational and Management Information

Korean Air evolved from Korean National Airlines, a government-owned carrier

established in 1948 to provide domestic air service from Seoul to Pusan. The airline was

privatized in 1969 and renamed Korean Airlines. The name was again changed to Korean

Air Company, Ltd., d.b.a. Korean Air, in the 1980s. 

Korean Air, based at Seoul’s Kimpo International Airport, operates domestic

routes to 16 airports and international routes to 54 airports, including those in North

America, Europe, the Middle East, Southeast Asia, China, Australia, and Japan. 

At the time of the flight 801 accident, Korean Air had a fleet of 116 airplanes:

2 Boeing 747-SPs, 15 Boeing 747-200s, 3 Boeing 747-300s, 26 Boeing 747-400s,

2 Boeing 777s, 5 McDonnell Douglas MD-11s, 14 McDonnell Douglas MD-82s,

10 Airbus A-300s, 2 Airbus A-330s, 25 Airbus A-300-600s, and 12 Fokker F.100s.

Korean Air stated that its fleet was expected to grow to approximately 175 aircraft by 2005.

Korean Air employed approximately 1,600 flight crewmembers at the time of the

flight 801 accident. In an interview with Safety Board investigators, Korean Air

management personnel stated that pilot recruitment at the company had historically been

from the Korean military. However, as the airline grew, the supply of available Korean

military pilots could not keep pace with the rapidly increasing demand for pilots at the

company. Because of this shortage, Korean Air recruited foreign nationals to supplement

its pilot force. At the time of the accident, 167 foreign national pilots were employed by

Korean Air. (Most of these foreign pilots were from the United States and Canada and

were hired through several crew leasing companies; the pilots’ employment was subject to

the terms of a renewable contract.) Of the 128 captains assigned to 747-200, -300, and -SP

airplanes at the time of the accident, 69 were foreign national pilots. 

Also, partly as a result of the pilot shortage, Korean Air began what it referred to as

an “ab-initio” (that is, from the beginning) program in 1989 that was designed to select and

train candidates from zero flight time. According to a Korean Air representative, ab-initiotrained pilots were initially assigned to the smaller airplanes used to fly domestic routes. As

the pilots gained experience, they were upgraded to the larger airplanes used primarily to

fly international routes. At the time of the accident, 389 pilots had been trained under the

ab-initio program, and Korean Air estimated that the first group of ab-initio pilots would be

evaluated for possible upgrade to captain during 1998. In September 1999, a KCAB official

stated that the first ab-initio-trained pilots were being upgraded to captain. 

77 The FAA engineer indicated during his testimony that voices and music contain 90- and 150-Hz

components.
Factual Information 53 Aircraft Accident Report

The Korean Air Deputy Director of Flight Operations testified at the Safety

Board’s public hearing that the Korean economy had been in a recession and that,

although 1995 was “a good year,” 1996 and 1997 were “in the red.” This official also

testified that, despite economic pressures, additional funding had been allocated by the

company for safety programs. The Deputy Director of Flight Operations, in his closing

remarks at the public hearing, stated:

Looking back upon this accident we feel that most of our management up to now

has been [ ] perhaps too short-term, short-[sighted], and superficial in its nature.

...from this point on for the purpose of ascertaining safe flight operations we plan

to make long-term plans and spare no resources in [attaining] this final objective

of flight safety. Accordingly, we will adjust our management systems and invest

all the more heavily into training and program development.78

In a March 26, 1998, letter, however, Korean Air requested that the Safety Board

remove the Deputy Director of Flight Operations’ statement from the public hearing

record. In its letter, Korean Air maintained that the deputy director’s statement was

“personal in nature” and “made in accordance with the Korean custom to express

condolences on public occasions to those affected by an accident.” The letter also said that

“the statement could suggest a finding by [Korean Air] of management deficiencies

having been ascertained as a result of internal review” and that “there has been no such

finding or review.” Further, the letter expressed Korean Air’s belief that the company’s

management structure “is competent to perform its functions.” The Safety Board did not

delete the statement from the record.

According to the KCAB, Korean Air’s president resigned in April 1999 as a result

of government criticism. The vice president of Korean Air was subsequently promoted to

president and chief executive officer.

1.17.1 Korean Air Postaccident Safety Initiatives

On October 9, 1998, the MOCT ordered Korean Air to suspend 138 flights per

week on 10 of its domestic routes for 6 months. According to the MOCT, the action

followed seven accidents/incidents (including the August 5 and September 30, 1998,

events listed in section 1.17.5.2). The MOCT ordered the airline to reduce service on its

Seoul to Tokyo route from 28 to 26 flights per week. According to a KCAB

representative, “these accidents/incidents were without human casualties, but we mete out

the severe punishment as a warning.” The KCAB indicated that other administrative

actions against Korean Air included the following:

• increased captain qualification requirements for large aircraft (including the 747),79

• prohibition of initial assignment of large aircraft for first officers,

78 Korean Air’s Deputy Director of Flight Operations further testified that “...starting on the 1st of April

[1998] the company is under contract to receive expert consultation of comprehensive nature from a wellknown and well-respected international organization.”
Factual Information 54 Aircraft Accident Report

• increased simulator training for CRM and line-oriented flight training (LOFT), and

• special simulator training for adverse weather conditions. 

After the MOCT took action, Korean Air announced that it planned to spend more

than $100 million over the next 2 years on safety initiatives, including changes in pilot

training and maintenance operations. Korean Air also stated that it planned to accomplish

the following: 

• install enhanced GPWS on all new aircraft and upgrade traffic alert and

collision avoidance systems (TCAS) on all airplanes; 

• recruit safety specialists to provide safety awareness training to all flight

crewmembers;

• conduct regular aircraft-specific safety and training sessions for flight crews,

including an expanded controlled flight into terrain (CFIT) awareness program

in both initial and upgrade training;

• develop a “safety alert system” in which data about incidents, accidents, and

irregular operations are gathered from every department and analyzed to

identify trends and develop accident prevention strategies; 

• revise simulator scenarios that reflect a variety of situations that may be

encountered during line operations, including takeoffs and landings from

different airports, TCAS avoidance maneuvers, and ground proximity escape

maneuvers;

• standardize pilot callouts, improve takeoff, approach, and landing checklists,

and enhance pilots’ knowledge of local terrain; and

• ensure that all flight crewmembers receive CRM and LOFT classes that require

“efficient and effective communication in the cockpit and cabin through

simulated situations.”

Korean Air also indicated that it planned to mandate a 30-day English language

training course and implement a confidential pilot reporting system so that errors and

concerns can be reported to the chief pilot without fear of reprisal. In addition, the airline

implemented a “maintenance error decision air program” designed to detect potential

maintenance anomalies caused by human error. 

In May 1999, Korean Air’s new president issued a safety policy statement and

additional material to support the company’s planned safety enhancements. Specifically,

Korean Air reevaluated its operational philosophy and adopted a five-point “Immediate

Action Plan,” which contained safety measures that were designed to “minimize exposure

79 The increased requirements were a 2-year freeze period as a captain on small- and medium-sized

aircraft in Korean Air’s fleet, 500 landing cycles on small- and medium-sized fleet aircraft, 350 landing

cycles on large fleet aircraft, and 4,000 hours of flight time with the company. 
Factual Information 55 Aircraft Accident Report

to risk, eliminate known hazards, and curtail operations under circumstances where there

may be reduced margins of safety.” 

First, the Immediate Action Plan imposed operational limits at five airports in

Korea to minimize exposure to risk when the margin of safety may be reduced. For

example, at three of the five airports, no operations can be conducted at night when the

runways are wet or crosswinds exceed 15 knots. Second, the plan contained Korean Air’s

revised policies and procedures for operations under slippery runway conditions80 and the

use of automation.81 Third, the plan included Korean Air’s decision to outsource flight

simulator training.82

Fourth, the Immediate Action Plan stated that Korean Air’s most important

operating priority is safety. According to Korean Air, every company line captain

participated in a series of seminars in April 1999 in which the captain’s decision-making,

authority, and responsibilities were redefined. These seminars reemphasized that the

captain “serves as the first, and last, line of quality assurance for [Korean Air], and is

charged with final responsibility for the safety of its flight operations.” 

Last, the plan provided senior management’s commitment to enhance decisionmaking, especially as it relates to flight safety matters. The plan stated that Korean Air

created an Executive Action Council to resolve critical operational and support issues in a

timely manner and a Flight Operations Action Team to identify and resolve critical flight

operations issues. 

According to Korean Air, new flight crew work rules will become effective in

October 1999. The new rules are expected to be similar to the duty and rest standards

established under 14 CFR Part 121 and the practices of leading airlines in the industry.

Korean Air indicated that its goal was to eventually achieve a standard of 80 hours of

flying time per month. Also, Korean Air stated that it was in the process of implementing

an automated flight crew scheduling system purchased from Sabre Technologies. This

new system was designed to monitor crew training and instrument and landing currency

and automatically update compliance with flight and duty limitations. The system was

expected to be fully implemented by the end of 1999. 

80 Regarding Korean Air’s revised policy on slippery runway conditions, the Immediate Action Plan

stated that “wind gusts are to be taken into account when computing maximum allowable cross/tailwinds,

allowable wind conditions must be adjusted to take into account braking action categories...[and] auto land

approaches, new minimum stopping distances...[and] improved guidelines for determining wet runways

must be observed, and more stringent takeoff and landing restrictions for marginal runway conditions have

been adopted.” 

81 According to Korean Air’s Immediate Action Plan, “automation should be at the most appropriate

level. The level used should permit both pilots to maintain a comfortable workload distribution and maintain

situational awareness.” 

82 Korean Air decided to outsource all simulator training activities to FlightSafetyBoeing. The details

for this arrangement were finalized in June 1999. Korean Air expected that the outsourcing program would

begin in the latter part of 1999. 
Factual Information 56 Aircraft Accident Report

In addition, Korean Air indicated that it has been revising its Flight Operations

Manual, Aircraft Operating Manual for each aircraft type, Operations Data Manual, and

Aircraft Restriction Manual from the manufacturer-supplied versions to reflect the

company’s standard operating procedures and achieve standardization. According to

Korean Air, 8 of the total 21 chapters of the Flight Operations Manual were revised and

distributed to all flight crewmembers on August 1, 1999, and the rest of the chapters were

expected to be revised and distributed during October 1999. Korean Air also indicated that

all of the company’s Aircraft Operating Manuals had been revised and issued according to

each aircraft manufacturer’s schedule. A Korean Air representative said in September

1999 that the Boeing 747 operating manual had been revised four times since the flight

801 accident.

1.17.2 Korean Air Flight Crew Training

Flight crew training is currently conducted at one of two facilities in Korea.

Ground instruction is conducted at the Korean Air Flightcrew Training Center in Seoul,

and simulator flight training is conducted at the Korean Air Simulator Flight Training

Facility in Inchon. (Korean Air conducts its ab-initio training at the Sierra Academy of

Aeronautics in Livermore, California, and then at its Cheju flight training facility.) To

become qualified as a Korean Air flight instructor or evaluator, candidates must attend

1 week of ground school, 10 days of simulator observations, 10 days of practice simulator

instruction, CRM and LOFT seminars, and check rides. Program managers and senior

flight instructors provide supervision and ensure standardization.

1.17.2.1 Basic and Advanced Instrument Flight Course

Korean Air provides basic and advanced instrument flight courses for every

specific airplane training program. Pilots receive this training before their initial training

on the particular airplane for which they are qualifying. Because the captain of the

accident flight was initially trained on the Boeing 727, he took the 727 basic and advanced

instrument flight courses; likewise, because the first officer was initially trained on the

Boeing 747, he took the 747 basic and advanced instrument flight courses. (The captain

received training on the 747 in transition courses, which are discussed in section 1.17.2.2.)

According to Korean Air’s flight training curriculum at the time of the accident,

the basic instrument course consisted of eight 4-hour simulator periods and included

modules in air work and instrument departures, arrivals, and approaches. The advanced

instrument course, which expanded on the procedures taught during the basic course,

included avionics operation, standard instrument departures, noise abatement procedures,

standard terminal arrivals (STAR),83 and engine-out procedures. The advanced course

consisted of 10 4-hour simulator periods. The countdown/count up DME/localizer

procedure, such as the one depicted in the Guam ILS runway 6L localizer-only (glideslope

83 STARs are routes established for arriving IFR aircraft. Their purpose is to simplify clearance delivery

procedures and facilitate the transition between en route and instrument approach procedures.
Factual Information 57 Aircraft Accident Report

out) approach, was not included in any of the Korean Air simulator training scenarios for

either the basic or advanced instrument courses. 

1.17.2.2 Boeing 747 Flight Crew Training 

Korean Air’s Boeing 747 flight crew training includes initial and transition

training, which are presented in five units: ground school, cockpit procedures training,

simulator flight training, airplane local training (as required), and route training. The

captain and the flight engineer on the accident flight were trained according to the 747

transition training syllabus, and the first officer was trained according to the initial training

syllabus.

At the time of the accident, the 747 initial and transition ground school training

included instruction on general aircraft systems, normal procedures, abnormal and

emergency procedures, weight and balance, performance, limitations, differences,

Category II instrument approaches,84 a review period, and a test. The initial ground school

training syllabus allocated 177 hours of instruction for both pilots and flight engineers and

required about 28 hours of cockpit procedures training. The transition ground school

syllabus allocated about 153 hours of instruction for captains and first officers with type

ratings on other airplanes and about 157 hours for flight engineers with qualifications on

other airplanes. Pilots and flight engineers were required to complete about 24 hours of

cockpit procedures training.

Flight training for the initial and transition courses included 40 hours of simulator

time (10 4-hour training periods in which each pilot performed as a PF and a PNF for

2 hours) and a 2-hour proficiency check period. At the time of the accident, the Korean

Air simulator training syllabus for 747-100, -200, and -300 initial and transition training

consisted of 10 profiles that described the events to be accomplished during each training

period. Each profile listed the approaches to be performed, including the specific airport,

runway, weather, and airplane malfunction, and information on whether the approach

would be made to a landing or the reason for a missed approach or go-around. The

10 training profiles consisted of the following approach scenarios:

• 23 ILS approaches to runway 14 at Kimpo Airport;

• 5 VOR and VOR/DME approaches to runway 32 at Kimpo Airport;

• 2 NDB approaches, one to a runway at Cheju Airport and one to a runway at

another airport; and

• 1 localizer (LOC) approach to runway 14 at Kimpo Airport.

After accomplishing the 10 simulator training profiles, pilots were given a

proficiency check using the scenarios contained in the 11th simulator profile. Korean Air

84 Category II instrument approaches have minimums of 100 feet decision height (DH) and a runway

visual range of 1,200 feet.
Factual Information 58 Aircraft Accident Report

training records indicated that the 11th simulator profile consisted of four ILS approaches

to runway 14 at Kimpo Airport and one VOR/DME approach to runway 32 at Kimpo.

The 747-200 Simulator Training Guide for Instructors, dated February 1997,

detailed the various training scenarios used in 747-100, -200, and -300 simulator training

at the time of the accident.85 The training guide described only one of the nonprecision

approaches: the VOR/DME approach to runway 32 at Kimpo Airport. The description for

this approach included the DME distance to initiate gear and flap configuration changes

and specific vertical speed settings during step-down fixes on the approach procedure.

Also, this nonprecision approach scenario always involved DME that was located on the

airport and colocated and frequency paired with the primary approach navigational

facility. Thus, all simulator approach scenarios using DME were approaches for which the

pilot had to count down toward the MAP. 

The simulator training curricula did not contain nonprecision approaches to other

airports or with varied or diverse scenarios. For example, no approach scenarios required

the pilot to count down to the DME, fly past the DME, and count up to the MAP, which

was required for the runway 6L ILS localizer-only (glideslope out) approach to Guam. At

the Safety Board’s public hearing, Korean Air’s Director of Academic Flight Training and

a Korean Air check airman testified that the simulator scenarios were to be followed as

published in the training curricula. They also indicated that there were no provisions or

guidance that enabled instructors to vary the nonprecision approach scenarios from those

published. 

The Korean Air Simulator Training Guide contained specific approach scenarios

to be used during proficiency checks and type rating simulator checks. These approach

scenarios were the same ones taught and practiced during the initial and transition training

sessions.

After the accident and subsequent discussions with the Safety Board, the KCAB

asked Korean Air to modify its simulator training syllabus to include diverse approaches.

The Safety Board notes that the Korean Air simulator training now incorporates a variety

of approach scenarios, including approaches in which the DME is not colocated with an

on-airport navigational facility and approaches involving countdown/count up DME

procedures. Also, the simulator training now includes approaches that are likely to be

encountered during domestic and international line operations.

1.17.2.3 Crew Resource Management Program

The Korean Air Director of Academic Flight Training stated that the company

instituted a CRM training program in December 1986 as a result of the Korean Air shoot

down accident in August 1983 off the coast of the Soviet Union. The director stated that

the CRM sessions are not graded and that no program records are kept. Pilots are

evaluated on CRM during route checks and proficiency check rides. In addition, pilots

receive LOFT86 during simulator sessions once a year and are evaluated based on how

85 Korean Air used a 747-200 model simulator to train 747-100, -200, and -300 pilots.
Factual Information 59 Aircraft Accident Report

they interact in coping with various anomalies during the simulated flight. According to

Korean Air, a total of 1,614 flight crewmembers had successfully completed CRM

training classes as of May 1999.

The CRM program that was in place at the time of the flight 801 accident was

developed from the United Airlines CRM program and adapted with the assistance of an

outside contractor. This 4-day program, which was provided to flight crews only,

emphasized dilemma resolution and focused on teamwork and leadership in problemsolving at the individual, crew complement, and organizational levels. The CRM program

used reading materials, films, and class exercises to help flight crewmembers recognize

and improve aspects of their behavior and interaction. The Director of Academic Flight

Training testified that this CRM program taught first officers and flight engineers to

intervene and challenge the captain if they had safety or operational concerns. He noted

that the company had encountered difficulties teaching some first officers and flight

engineers to challenge the captain and intervene in safety-of-flight situations. The director

also testified that this issue was no longer a problem in training and that captains were

being taught to encourage a cockpit environment in which first officers and flight

engineers could freely express concerns when necessary.

In May 1999, Korean Air announced it would replace the existing CRM program

with a new CRM program that was developed with and adopted from Delta Air Lines. The

new program will consist of four courses: a base course, a course for new captains, a

recurrent course, and a recurrent joint flight operations/cabin services course.87 The onetime base course, called “Error Management CRM,” will last 5 days: the first 3 days will

be classroom instruction, the fourth day will be a jumpseat observation flight, and the fifth

day will be a debriefing session. The one-time “In-Command” course for new captains

will last 1 day. The 1-hour pilot recurrent course and the 3-hour recurrent joint flight

operations/cabin services course will be presented each year. According to Korean Air, the

courses will be taught through lectures, class exercises, reading material, and other

techniques to impart practical skills for the crews. In addition, Korean Air stated that its

new CRM course would add “realism” to training through an audio-visual presentation

format. Korean Air indicated that it expected to implement this program by January 2000. 

1.17.2.4 Postaccident Changes to Flight Training

In addition to the changes being implemented in response to the MOCT action and

as part of the Immediate Action Plan and the new CRM program, Korean Air indicated

that it has made other changes in the area of flight training. For example, the company’s

Flight Standards Branch, within the Flight Operations Department, is now primarily

responsible for overall quality assurance for all flight training and checking activities.

Other changes are as follows:

86 According to Korean Air, the company began LOFT in 1992 using the 747-200. In 1993, this training

was expanded to the 747-400 and the MD-82. The training eventually covered all aircraft types and models. 

87 The purpose of this course is to increase team abilities to handle abnormal situations through

cooperative efforts between flight and cabin crewmembers.
Factual Information 60 Aircraft Accident Report

• Beginning in November 1998, training modules on risk and error management

and recovery training for CFIT awareness, GPWS and windshear warnings,

slippery runways, and crosswind and icing conditions were added to the

recurrent proficiency training curriculum for all airplane types. 

• In January 1999, a policy of training to proficiency in the recurrent training and

checking system was implemented. Crewmembers are to be given three

opportunities during recurrent training and checks to receive additional

instruction and correction while training to the acceptable level of proficiency.

• Also in January 1999, the Flight Operations Department changed its system for

selecting candidates for aircraft transition and upgrade to incorporate “more

objective” criteria. The standards for upgrading to captain were also revised.

The new standards increase the minimum requirements from 3 years and

3,000 hours to 5 years, 4,000 hours, and 350 landing cycles with the company

regardless of previous military or other aviation experience. 

• In April 1999, new standardized flight instruction manuals were issued.

• A new Line Check Pilot Manual was being developed to include detailed

procedures and requirements so that check pilots could consistently apply and

enforce company standards and policies. The new manual was expected to be

completed in October 1999. 

• The Flight Operations Department developed a new all-volunteer system, to

replace the previous assignment system, for all line check pilots. Candidates

who volunteer for these positions are to be selected based on their ability to

judge deficiencies in training and impart line flying skills. Also, the training

requirements for line check pilots were increased so that the check pilots could

impart better decision-making and crew coordination skills to the line pilots.

1.17.3 Korean Air Preflight Procedures

The Korean Air Operations Manual that was in effect at the time of the accident

(dated May 21, 1997) stated that crewmembers were to arrive at the company dispatch

center at least 1 1⁄2 hours before the scheduled departure time for international flights.

According to company procedures at the time, flight crewmembers were to receive their

paperwork and then gather as a group to study the paperwork. This process, referred to as

the “self-briefing,” typically lasted about 15 minutes. The flight crewmembers then met

with their assigned SOF for the “SOF briefing.” Afterward, the captain met with the flight

and cabin crewmembers for a “full crew briefing.”

Korean Air stated that, in March 1999, it began issuing “flight-specific manual

packages” to outbound crews to ensure that pilots possessed updated route information for

each trip. In addition, the company said that it developed an airport information program

to promote additional route and airport familiarization. Korean Air expected that this

program would be completed by the end of 1999 and that it would cover all of the airports

serviced by the company’s aircraft. 
Factual Information 61 Aircraft Accident Report

1.17.3.1 Supervisor of Flying Program

According to Korean Air officials, the company’s SOF program began in 1996.

The officials described the SOFs as retired captains and instructors who were among the

company’s most experienced pilots and had no record of disciplinary action. The officials

stated that the purpose of the SOF briefing was to ensure that pilots had reviewed all

pertinent materials for the flight, including any NOTAMs. Further, the SOFs were

expected to periodically check crewmembers’ charts and manuals for currency as well as

their airman certificates and passports, which are required documents for international

flights. There is no formal checklist of items to be covered in the SOF briefing. The

officials stated that the SOF briefings were designed to last 15 minutes but averaged about

10 minutes. 

In a postaccident interview with Safety Board investigators, the Korean Air

Deputy Director of Flight Operations said that he initiated the SOF program to correct

pilot performance deficiencies that were involved in the accident/incident events (see

section 1.17.5.1) and violations that the company had been experiencing.88 Further, the

deputy director said that he was not aware of any other air carrier that had a SOF program

and that he believed the number of accident/incident events and violations had

dramatically declined since the initiation of this program.

The SOF for Korean Air flight 801 was a retired company 747 captain. The SOF

stated, in a postaccident interview, that he reviewed the flight data and asked the flight

crew about the weather conditions en route to and at Guam. The SOF also stated that he

and the flight crew discussed a typhoon and the possibility of en route turbulence and that

he recommended maximum use of the weather radar. The SOF further stated that he and

the flight crew discussed company notices but did not discuss the NOTAMs pertaining to

Guam and the out-of-service glideslope associated with the runway 6L ILS approach.89

The SOF did not check the flight crew’s charts for currency. The SOF said that his main

concern was to confirm that the flight crewmembers had “looked at the [trip paperwork]

items closely.”

1.17.3.2 Airport Familiarization Program

Korean Air stated that, in June 1997, it established an airport familiarization

program that used audio-visual presentations (purchased from Japan Airlines) to prepare

pilots for operations into designated airports. Korean Air requires that an airport

familiarization tape be viewed if the company or the FAA list that airport as a “special

airport.” Title 14 CFR Section 121.445 defines special airports as those that require a

special airport qualification for pilots-in-command because of “surrounding terrain,

88 In a postaccident interview, the Deputy Director of Flight Operations stated that Korean Air had

incurred 17 violations in 1996. 

89 A Korean Air representative stated that the captain was responsible for reviewing applicable

NOTAMs during the self-briefing and discussing any questions about them with the company dispatcher.

According to the SOF, the flight crew did not indicate that there were NOTAMs regarding the flight. The

SOF also indicated that he was unaware of the NOTAM regarding the inoperative glideslope.
Factual Information 62 Aircraft Accident Report

obstructions, or complex approach or departure procedures.”90 Guam International Airport

was not classified by Korean Air or the FAA as a special airport; thus, the accident flight

crew was not required to view this familiarization tape. However, Korean Air

recommends that pilots view a familiarization video if they have not flown into the

destination within the preceding 3 months. The airport videotapes are available to pilots

6 days a week. 

The audio-visual presentation for Guam gave a general description of Guam’s

weather and topography, including Mount Alutom, located near the outer marker, and

Mount Macajna, located north of the NIMITZ VOR. The presentation advised pilots that

“...when you report airport-in-sight, you will be cleared for a visual approach.” Further,

the presentation stated that “...you [the pilot] will be radar-vectored to ILS runway 6L....

Normally, you will be guided from over Apra Harbor to the localizer.... You will then

perform a visual approach.” The presentation highlighted the visual approach, identified

visual cues for the approach to runways 6L and 24R, and advised pilots not to fly over a

hospital located northwest of the airport.

1.17.4 Korean Air Descent and Approach Procedures

1.17.4.1 Briefing and Checklist Usage

A Korean Air instructor pilot testified at the Safety Board’s public hearing that the

company required the PF to conduct an approach briefing for every approach and that the

briefing was to include the division of crewmember duties during the approach

procedures. The instructor pilot stated that, if a pilot receives information that a

navigational aid, such as a glideslope, was reported to be unreliable or unusable, Korean

Air policy requires the pilot not to use that navigational aid to conduct the approach. The

Korean Air 747 checklist booklet contained a landing briefing card (dated September 10,

1996), listing the following required items for a landing (or approach) briefing:91

LANDING BRIEFING

1. WEATHER

2. STAR

• TOD

• No 1 & No 2 VOR/ADF Courses

• ALT [altitude] & SPD [speed] Restrictions

• Arrival Routes

3. USING RUNWAY, TYPE OF APPROACH, AND TRANSITION LEVEL

90 See section 1.18.8 for more information on 14 CFR Section 121.445 and safety recommendations to

the FAA on special airport criteria and designation.

91 In this report, the term “landing briefing” is synonymous with “approach briefing.”
Factual Information 63 Aircraft Accident Report

4. REVIEW OF INSTRUMENT APPROACH PROCEDURES

• Minimum Safe Altitude

• Approach Frequency (ILS, VOR, ADF)

• Approach Course

• Touch Down Zone Elevation

• Missed Approach Procedure

• Holding Procedure

5. CREW ACTION AND CALL OUT

6. PARKING SPOT AND TAXI WAYS

* DOCKING GUIDANCE SYSTEM

7. OTHER ABNORMAL CONFIGURATION AND CONDITION

TIME: BRIEFING SHOULD BE COMPLETED PRIOR TO

ARRIVAL OVER TOD

The Korean Air instructor pilot testified that company pilots were taught to include

the following items in a nonprecision approach briefing: 

• ATIS information, including the weather, expected approach procedure, and

field NOTAMs;

• arrival and descent procedure to the IAF;

• runway, type of approach, and type of transition;

• transition level;

• instrument approach procedure in detail;

• airport name and chart number;

• approach plate issue and effective dates;

• minimum safe altitude;

• airport elevation;

• special notes;

• configuration of navigational receivers and how to tune and identify them;

• crew actions and callouts;

• procedure to intercept approach course;

• step-down altitudes and how they were determined;

• MDA and how it was determined;

• MAP;

• parking spot and taxiways; and

• instruction to nonflying crewmembers to call out any abnormalities or

deviation from procedures.
Factual Information 64 Aircraft Accident Report

Korean Air’s checklist philosophy, as described in its Boeing 747 Guidebook,92

states the following:

Normal procedures[93] for each phase of flight are performed by recall, and the

normal checklist is used to ascertain that all the safety items have been

accomplished. Each response to the checklist challenge should be preceded by the

verification of the present configurations, and the crewmembers should check for

conformation. If any disagreements have been found between present

configuration and checklist response, corrective actions should be taken first

before any further checklist challenge.

The Korean Air Boeing 747 Guidebook states that the “descent checklist” is to be

performed while the airplane is descending through 20,000 feet to approximately

18,000 feet (or 1,000 feet above transition level in North America). The guidebook also

states that the “approach checklist” is to be performed after a speed reduction to 250 knots

and while the airplane is descending through 10,000 feet with its inboard landing lights on

and that the “landing checklist” is to be performed when the airplane has been configured

for landing.

1.17.4.2 Flight Crew Actions and Callouts During Nonprecision Approaches

A Korean Air simulator instructor testified that the company trained its pilots to

utilize the step-down rather than the “constant angle of descent”94 technique when

executing nonprecision approaches. However, the instructor stated that captains were

permitted to use the constant angle of descent approach technique under visual conditions

provided that they did not descend below the published intermediate step-down altitudes.

The Korean Air simulator instructor also stated that, at the time of the accident,

pilots were trained to fly a nonprecision approach with the autopilot either engaged or

disengaged. With the autopilot engaged, the PF was instructed to program the

autopilot/FD controls, including vertical speed and the altitude select, unless the PF

specifically directed the PNF to perform that function. In addition, the PF was instructed

to initiate all heading, course, and altitude changes, including the selection of the

step-down altitudes, while executing the approach profile. Further, the PNF was instructed

to monitor the approach and challenge the PF when necessary.

92 The Boeing 747 Guidebook is a Korean Air procedures and technique training aid. It is published in

Korean and English. The edition in effect at the time of the accident was dated August 1993. 

93 Korean Air states that normal procedures “...are the recommended actions necessary to operate the

airplane for each phase of flight. They enable the flightcrew to more readily memorize the required items,

ensure that all necessary actions have been taken, and minimize the time required.”

94 The constant angle of descent technique requires pilots to maintain a predetermined constant angle

and constant rate of descent, which is generally calculated to be about 3°, except when terrain or an obstacle

necessitates a steeper descent. When a ground-based glideslope signal is absent, pilots can fly the constant

angle of descent approach by using flight management system (FMS) and GPS equipment for electronic

guidance. (See section 1.10.3.1 for a description of the step-down technique.) 
Factual Information 65 Aircraft Accident Report

Korean Air did not provide the Safety Board with any documentation from its

operations or training manuals on specific PF and PNF roles and duties taught during

ground and simulator training. For approach procedures, the only specified duties for the

PNF, as described in Korean Air’s Boeing 747 Guidebook and 747 Aircraft Operating

Manual (page 04.27.01, dated January 30, 1980), were as follows: 

• Position flap lever as directed.

• Prior to crossing the outer marker cross-check all flight and navigation

instruments, observe all warning flags retracted and all radios tuned to correct

frequencies.

• Position landing gear lever down on command.

• Use windshield wipers and rain repellant as required.

• Check AUTO SPOILERS and AUTO BRAKE DISARM lights. 

The Korean Air 747 Aircraft Operating Manual (dated October 1, 1984) described

the following conditions and locations and the standard callouts for the PNF (with the

flight engineer monitoring) during IFR conditions:

• First positive INWARD motion of localizer bar: “Localizer.”

• First positive motion of glide slope bar: “Glide slope.”

• Final fix inbound (altimeter, instrument, and flag crosscheck): “Outer

Marker/VOR/NDB/etc., Time, ____ Feet, altimeters and instruments

crosschecked.”

• 1000 and 500 ft above field elevation (altimeter, instrument, and flag

crosscheck): “1000/500, altimeters and instruments crosschecked.”

• After 500 ft above field elevation: (Call out significant deviations from

programmed airspeed, descent, and instrument indications.)

• 100 ft above DH [decision height]/100 ft above MDA: “100 above.”

• Reaching DH or MAP: “Minimums, approach/strobe/centerline lights—

runway (or no runway).

Korean Air indicated that Standardization Circular 90-07, “747 Standard Callouts”

(dated April 1996), described actions and callouts to be made during a nonprecision

approach. The Standardization Circular Manual, which was issued to all pilots, contained

general and aircraft-specific information. However, the callouts were not included in

Korean Air’s Boeing 747 Aircraft Operating Manual, company Operations Manual, or

747 Flight Crew Training Manual. Korean Air indicated in July 1999 that its pilots were

trained to use the standard callouts during initial simulator training and were checked for

the use of these callouts during simulator and line checks. Korean Air also stated that its

pilots “always take this document in flight” and that the document is “readily available to
Factual Information 66 Aircraft Accident Report

pilots.” The callouts presented in the standardization circular for the PF, PNF, and flight

engineer (F/E) are as follows:95

At 20,000 ~18,000 Feet msl:

PF Initiates Descent Checklist

PNF N/A

F/E Executes Descent Checklist

Approaching Transition Level:

PF Transition Altimeter Reset

PNF Transition Altimeter Reset

F/E Transition Altimeter Reset

At 10,000 Feet msl:

PF Initiates Approach Checklist

PNF Calls “One Zero Thousand”

F/E Executes Approach Checklist

1,000 Feet Above Initial Approach Altitude:

PNF Calls “One Thousand to Initial”

PF Responds to PNF “Roger”

F/E N/A

On Intercepting Heading (Check VOR/NDB Freq. and Inbound Course):

PF Select VOR/LOC Mode

PNF Confirms “Select VOR/LOC Mode’

F/E Monitor Auto Mode and Monitor Instruments

First Positive Inward Motion of Localizer Bar:

PNF “VOR Approach;**” “CDI [course deviation indicator] Alive;” 

“CDI Capture;” (NDB Approach**)

PF Responds “Roger”

F/E Monitor Auto Mode, Monitor Instruments

**PF Orders flap extension on approach then calls “Command Bug Set”

PNF Responds “Command Bug Reset”

PF Sets Auto Brake and Places Speed Brake Lever

95 Some international air carriers have the PNF lead or prompt the PF through the nonprecision

approach procedure by stating the next procedural change, including course, heading, altitude, time, visual

contact, and MAP. Further, some air carriers have the captain serve as the PNF (until just before landing) and

monitor the first officer’s performance (as the PF) during the approach procedure. 
Factual Information 67 Aircraft Accident Report

After CDI LOC Bar Moving:

PF Requests “Set Inbound Heading”

PNF Responds “Setting Inbound Heading”

F/E N/A

Leaving Initial Approach Fix (IAF):

PNF States “Leaving IAF (name), Time Check, Altitude”

PF Responds “Roger”

F/E Monitors Altimeter and Altitude Cross Check, Monitor Instruments

Landing Gear Down and Landing Checklist:

PF Calls Gear Down, Flaps Down (incrementally), Requests 

“Landing Checklist”

PNF Responds to confirm gear position and flap position

F/E Executes Landing Checklist

Over Final Approach Fix (Call “Time” and Push Clock Button):

PF States “Outer Marker/Final Approach Fix”

PNF Responds “Outer Marker/Final Approach Fix, Time, Altimeter, 

and Instrument Cross-Check”

F/E Monitors Altitude, Attitude and Airspeed

1,000 Feet Above Field Elevation (Altimeter, Instrument & Flag Check):

PNF States “One Thousand”

PF Responds “No Flag, Gear and Flaps”

F/E Responds “No Flag, Gear and Flaps” and Monitors Instruments

On Final Approach—Deviation Call:

The PNF will call any of the following deviations—Bank 15 degrees at or above,

DME & Altitude, CDI Exceeds 1/3 dot, Indicated Airspeed exceeds 10 knots,

Below Minimum Altitude, Too High or Low on VASI or PAPI [precision approach

path indicator]

100 Feet Above MDA:

PF Looks for Visual Cues

PNF States “One Hundred Above”

F/E Monitors Instruments

At MDA:

PNF States “Minimums”

PF Responds “Roger”

F/E Monitors Instruments
Factual Information 68 Aircraft Accident Report

1.17.4.3 Terrain Avoidance Recovery Maneuvers

At the time of the accident, one manual issued to Korean Air flight

crewmembers—the company’s 747 Aircraft Operating Manual—contained written

guidance on when to execute a recovery maneuver to avoid terrain. Under the section

entitled “PULL UP/TERRAIN AVOIDANCE,” the manual stated: 96

The published RECOVERY MANEUVER procedure is immediately

accomplished by recall whenever the threat of ground contact exists. Either of the

following conditions is regarded as presenting a potential for ground contact:

• Activation of the “PULL UP” warning.

• Inadvertent windshear encounter or other situations resulting in unacceptable flight

path deviations.

Korean Air’s 747 Aircraft Operating Manual (page 14.20.02, dated November 2,

1992), required the following procedures for the recovery maneuver:

Aggressively position the thrust levers forward to ensure maximum thrust is

attained, disengage autopilot and autothrottle (as installed), and rotate smoothly at

a normal rate toward an initial pitch attitude of 15 degrees.

Do not use flight director commands.

Pitch attitudes in excess of 15 degrees may be required to silence the “PULL UP”

warning and/or avoid terrain.

Note: In all cases, the pitch attitude that results in intermittent stick shaker or

initial buffet is the upper pitch attitude limit (this may be less than 15 degrees in a

severe windshear encounter).

Large thrust increases may result in a nose-up pitching tendency requiring

forward column pressure and trim.

Monitor vertical speed and altitude. Do not attempt to change flap or gear position

or regain lost airspeed until ground contact is no longer a factor.

1.17.5 Korean Air Accident and Incident History

The Safety Board used data provided by Airclaims Limited97 to compare Korean

Air’s safety record with the records of five major U.S.-based airlines and five major

Asian-based airlines. The total hull loss records for all of these airlines were calculated for

a 10-year period ending December 31, 1998, using two measures of activity or exposure to

96 Most U.S. airlines refer to this procedure as the escape maneuver.

97 Airclaims Limited is an aviation consulting firm that collects data, in part, for the aviation insurance

industry. The Airclaims Limited database is recognized by the aviation industry as a definitive source for

worldwide aviation accident information. Loss data for this comparison were retrieved from Airclaims

Client Aviation System Enquiry database and were current as of August 10, 1999. Exposure data were

retrieved from Airclaims Limited, Jet Operator Statistics, 1999, issue 1. 
Factual Information 69 Aircraft Accident Report

risk: aircraft flight hours and departures. Airclaims Limited defines a total loss as an

aircraft that has been destroyed or for which the estimated repair costs rendered the

aircraft a total loss under the terms of the insurance contract. (Airclaims Limited notes that

some airplanes that became total losses were repaired and returned to service.) Any total

loss that resulted from a deliberate violent act was eliminated from the Board’s

comparison. The results of the comparison are shown in table 3.

As table 3 indicates, eight of the operators had fewer than one hull loss per

1 million flight hours (All Nippon Airways, Singapore Airlines, Japan Airlines, Northwest

Airlines, United Airlines, US Airways, Delta Air Lines, and American Airlines). Asiana

Airlines had 1.25 hull losses per 1 million flight hours, Korean Air had 2.38, and China

Airlines had 4.59.

Seven operators in the comparison group had fewer that one hull loss per 1 million

departures (All Nippon Airways, Japan Airlines, Northwest Airlines, United Airlines,

US Airways, Delta Air Lines, and American Airlines). Two operators had between one

and two hull losses per 1 million departures (Singapore Airlines and Asiana Airlines).

Korean Air Lines had 4.79 hull losses per 1 million departures, and China Airlines

had 11.74.

Table 3. Loss totals and rates for the 10-year period ending December 31, 1998, 

by losses per 1 million departures.

Operator Lossesa

a Loss totals include all total hull losses, excluding acts of violence.

Aircraftb

b Aircraft hours and departures are expressed in thousands.

Losses per aircraftc

c Loss rates are expressed as accidents per 1 million aircraft hours and 1 million departures.

Hours Departures Hours Departures

All Nippon Airways 0 2,751 2,069 0.00 0.00

Japan Airlines 0 3,535 1,396 0.00 0.00

Delta Air Lines 1 15,988 9,614 0.06 0.10

Northwest Airlines 1 10,570 5,598 0.09 0.18

United Airlines 2 16,075 7,273 0.12 0.27

American Airlines 3 18,823 8,607 0.16 0.35

US Airways 6 11,700 8,988 0.51 0.67

Singapore Airlines 1 2,351 598 0.43 1.67

Asiana Airlines 1 803 576 1.25 1.74

Korean Air 6 2,522 1,252 2.38 4.79

China Airlines 5 1,090 426 4.59 11.74
Factual Information 70 Aircraft Accident Report

1.17.5.1 1983 to 1997 Accident History

Between 1983 and the time of the flight 801 accident, Korean Air experienced

several accidents that were attributed primarily to pilot performance.98 Some of these

accidents resulted in substantive management, operational, and policy changes initiated by

the company to correct deficiencies identified by the accident investigations. The

following is a brief description of some of these pilot performance accidents:

• On August 31, 1983, Korean Air flight 007, a 747-200B, crashed in the Sea of

Japan off Sakhalin Island, Soviet Union, killing 269 people. Although the

airplane was intentionally shot down, the investigation99 revealed the flight

crew likely made a navigation entry error in the autopilot, causing the airplane

to depart from its assigned flightpath without the crew’s detection and

subsequently enter restricted airspace in the Soviet Union.100

• On December 23, 1983, Korean Air flight 084, a Douglas DC-10 on a

scheduled cargo flight, collided head on with SouthCentral Air flight 59, a

Piper PA-31 on a scheduled commuter flight, on a runway at Anchorage,

Alaska, in heavy fog. Three people received serious injuries, and three people

received minor injuries. The Safety Board determined that the probable cause

of the accident was the failure of the Korean Air pilot to follow accepted

procedures during taxi, which caused him to become disoriented while

selecting the runway; the failure of the Korean Air pilot to use the compass to

confirm his position; and the decision of the Korean Air pilot to take off when

he was unsure that the aircraft was positioned on the correct runway.101

• On July 27, 1989, a Korean Air McDonnell Douglas DC-10-30 crashed in fog

about 1.5 kilometers short of the runway at Tripoli International Airport,

Libya, during the execution of a nonprecision approach (in which the ILS was

out of service).102 Of the 199 people on board the airplane, 4 crewmembers and

68 passengers died; 6 people on the ground were also killed. The Libyan Civil

Aviation Authority determined that the cause of the accident was improper

flight crew coordination likely influenced by fatigue.103

98 Some of these accidents occurred when Korean Air was known as Korean Airlines. For consistency,

Korean Air is used throughout this section.

99 See International Civil Aviation Organization (ICAO), Destruction of Korean Air Lines Boeing 747

on 31 August 1983, Report on the Completion of the ICAO Fact-finding Investigation, June 1993.

100 As stated in section 1.17.2.3, Korean Air instituted a CRM training program in December 1986 as a

result of this accident.

101 See National Transportation Safety Board. 1984. Korean Air Lines, McDonnell Douglas DC-10-30,

HL7339, SouthCentral Air, Piper PA-31-350, N35206, Anchorage, Alaska, December 23, 1983. Aircraft

Accident Report NTSB/AAR-84/10. Washington, DC.

102 See Libyan Civil Aviation Authority, Korean Air McDonnell Douglas DC-10-30 Korean Registration

ML-7328 crashed nearby Tripoli International Airport Southeast of Runway 27 on July 27, 1989. Aircraft

Accident Final Report.

103 According to Korean Air personnel, this accident resulted in upgrades of the Korean Air pilot training

program, including increased instrument flight time requirements, additional GPWS awareness in simulator

training, and the adoption of computer-based academic training.
Factual Information 71 Aircraft Accident Report

• On August 10, 1994, a Korean Air Airbus A300-620R landed long at a high

rate of speed and overran the runway at Cheju Airport, Korea, after an apparent

misunderstanding between the flight crewmembers as to whether they should

continue with landing or abort and execute a go around.104 All of the 160

airplane occupants survived the crash. The airplane was destroyed. According

to Korean Air personnel, both pilots were jailed temporarily, and neither

resumed flight service with the company.105

1.17.5.2 1998 and 1999 Accident and Incident History

Since the time of the Korean Air flight 801 crash, the company has experienced

several accidents and incidents, some of which are detailed below.

• On August 5, 1998, Korean Air flight 8702, a Boeing 747-400, HL7496,

skidded off the runway and crashed during a landing roll in heavy rain at

Kimpo Airport in Seoul. None of the 16 crewmembers were injured, and 65 of

the 379 passengers received minor injuries. The accident caused substantial

damage to the airplane. The KCAB’s investigation determined that the

accident was caused by the captain’s misuse of the thrust reverser during the

landing roll and his confusion over crosswind conditions.106

• On September 30, 1998, Korean Air flight 1603, a McDonnell Douglas

MD-82, HL7236, overran a runway at Ulsan Airport, Korea, in heavy rain.

None of the 6 crewmembers were injured, and 3 of the 142 passengers received

minor injuries. Both engines’ fan blades were damaged as a result of the event.

The KCAB determined that this event was the result of “high speed over a wet

runway.” 

• On March 15, 1999, Korean Air flight 1533, a McDonnell Douglas MD-83,

HL7570, overran a runway at Pohang Airport, Korea, during a second landing

attempt and crashed into an embankment. The accident occurred in stormy

weather with strong winds. One of the 6 crewmembers and 15 of the 156

passengers were injured. The airplane received substantial damage as a result

of the accident. The KCAB determined that the cause of the accident was the

flight crew’s “poor action” in bad weather (including gusts and variable

winds), misuse of the brake and thrust reverser during the landing roll, and lack

of decision-making for executing a go-around and stop.107 In addition, the

KCAB believed that the flight crew received poor ground assistance.

104 This information was contained in an Airclaims Limited major loss record.

105 According to Korean Air, this accident led to an increased awareness of the importance of speed

callouts during the approach phase of flight.

106 The KCAB subsequently suspended the captain’s flying status for 1 year and the first officer’s status

for 6 months. 

107 The KCAB subsequently suspended the captain’s ATP certificate and the first officer’s flying status

for 1 year. 
Factual Information 72 Aircraft Accident Report

• On April 15, 1999, Korean Air flight 6316, a McDonnell Douglas MD-11,

HL7373, crashed in a residential area of Shanghai, China, about 6 minutes

after takeoff.108 The two pilots and one mechanic on board the airplane were

killed. Additionally, at least 4 people on the ground were killed, and 37 others

were injured. The airplane was destroyed by impact forces. The accident is

being investigated by the Civil Aviation Administration of China with

participation by the Safety Board and the KCAB.

1.17.6 Oversight of Korean Air

1.17.6.1 Korean Civil Aviation Bureau 

As previously stated, the KCAB, a division within the MOCT, is responsible for

providing oversight of the Korean civil airlines. The Safety Board found that two KCAB

operations inspectors were assigned to provide oversight of Korean Air’s flight operations

at the time of the accident. Neither of these inspectors were type rated in any of the

airplanes operated by Korean Air. According to the KCAB, these two inspectors also had

oversight duties at Asiana Airlines, another domestic air carrier.

The KCAB stated that, before the flight 801 accident, it performed an annual 7-day

safety inspection, quarterly 7-day regional inspections, and random inspections an average

of 40 times per year. The KCAB also said that it frequently relied on Korean Air to selfreport corrective actions taken in response to KCAB inspections. 

During testimony at the Safety Board’s public hearing, the Korean Air Director of

Academic Flight Training stated that the KCAB approved all company aircraft operations

manuals, training manuals, training programs, and flight operations procedures.109 The

official also stated that the KCAB provided direct oversight of Korean Air and its training

curricula primarily during the annual safety inspection and two to three random operations

inspections each year. 

Korean Air’s Director of Academic Flight Training also testified that the KCAB

conducted almost all type-rating proficiency checks on the company’s Fokker F.100 and

McDonnell Douglas MD-82 airplanes. However, the official said that type-rating

proficiency checks on the other airplanes in Korean Air’s fleet, including the 747-200,

-300, and -SP, were conducted by company check airmen designated by the KCAB.110

Korean Air’s Director of Academic Flight Training could not recall any direct

surveillance by the KCAB on 747 proficiency checks or training sessions. The Korean Air

official indicated that, if company records indicated otherwise, he would forward such

108 Delta Air Lines, Air Canada, and Air France suspended their code-sharing agreements with Korean

Air after this accident. 

109 In addition, as stated in section 1.6, the KCAB was responsible for approving Korean Air’s

Continuous Maintenance Program.

110 These designated check airmen were authorized by the KCAB to conduct proficiency checks and

aircraft type rating checks. The KCAB conducted annual evaluations of the designated check airmen.
Factual Information 73 Aircraft Accident Report

information to the Safety Board after he returned to Korea. The Board never received any

such information from Korean Air. The KCAB, however, stated that it had written records

of such surveillance and that it had given these records to Korean Air.

The Korean Air Director of Safety and Security stated that the KCAB provided

oversight for the Korean Air simulator training syllabi during the annual safety inspection.

This director further stated that, before the accident, he was not aware of any KCAB

written criticisms or required changes to the Korean Air flight training program. The

Korean Air Director of Academic Flight Training testified that he could not recall any

KCAB written record of recommended or required corrective actions as a result of its

inspections before the Guam accident. However, the KCAB stated that it has written

records of recommended and required actions from its inspections before the accident. 

The KCAB stated that, after the flight 801 accident, it hired five inspectors (three

of whom were captains), two examiners, and two technical experts. The KCAB also stated

that it hired 14 commercial pilots to provide in-house technical expertise. These pilots,

however, are not directly involved in oversight activities. In addition, the KCAB

inspectors now assigned to Korean Air are type rated in the Boeing 747-400, and they

previously flew 747 Classics (that is, the 747-100, -200, -300, and -SP). 

Further, the KCAB indicated that, after the accident, it instituted the following

changes regarding its oversight of Korean Air: increased simulator training requirements

for adverse weather conditions, risk avoidance, GPWS, and terrain awareness; mandated

CFIT prevention concepts in recurrent ground school that are to be practiced in simulator

training; diversification of training scenarios, including those airports with approach

navigational aids that are not colocated with the field of landing; separate localizer and

VOR approach requirements included as training items for nonprecision approaches; and

a requirement to choose random profiles for check rides.

1.17.6.1.1 Accident and Incident Investigation Authority

The KCAB’s Division of Aviation Safety is responsible for aviation accident and

incident investigations. 

Paragraph 5.4 in Annex 13 to the Convention on International Civil Aviation

(Chicago Convention)111 specifies in part that “the accident investigation authority shall

have independence in the conduct of the investigation and have unrestricted authority over

its conduct.” Further, on November 21, 1994, the Council of the European Union (EU)

adopted a directive that specified that EU Member States would ensure, within 2 years,

that aviation accident and serious incident investigations were conducted or supervised by

a permanent body or entity that is functionally independent of the national aviation

authorities responsible for regulation and oversight of the aviation system. According to

111 Virtually all countries (including South Korea) are signatory to the Chicago Convention Treaty, which

established the standards and recommended practices for international civil aviation. Annex 13 addresses

aircraft accident and incident investigation. 
Factual Information 74 Aircraft Accident Report

EU officials, all EU Member States have complied with this directive or are moving

toward full compliance.

1.17.6.2 Federal Aviation Administration

Korean Air was granted authority to operate into U.S. airspace under the

provisions of 14 CFR Part 129 and International Civil Aviation Organization (ICAO)

Annex 6.112 The FAA approves operations specifications and assigns a principal

operations inspector (POI) to each foreign carrier.113 The POI assigned to Korean Air at

the time of the accident was not qualified in any of the airplanes operated by Korean Air,

but no international or FAA provisions require that inspectors be qualified or current in

any aircraft operated by the foreign air carrier for which they have responsibility. This POI

also provided oversight to six other international air carriers. The POI said that, at the

time, it was customary for the FAA to rotate inspectors of foreign air carriers so that each

foreign airline was assigned a different inspector every 1 to 2 years. 

The POI also said that there was no formal interaction between the KCAB and the

FAA regarding oversight of Korean Air. Neither civil aviation authority (CAA) was

required to formally or informally exchange reports of inspection activities or safety

concerns. The KCAB, however, indicated that it and the FAA have an ongoing exchange

of reports on inspection activities, violations, and certificate actions as well as safety

concerns.

Further, the POI assigned to Korean Air said that the FAA’s oversight role for Part

129 operators was to approve operations specifications, inspect trip records and facilities,

and accomplish ramp inspections of airplanes and crews when they were in the United

States or its territories. The POI also stated that the FAA did not inspect, approve, or

provide oversight for a foreign airline’s training or operations manuals. The Safety Board

has not identified any requirement under the Convention on International Civil Aviation or

the Federal Aviation Regulations (FAR) that the FAA be provided copies of these

manuals. In addition, the POI stated that the FAA did not conduct line checks or en route

inspections on board a foreign carrier. 

FAA Order 8400.10, “Air Transportation Operations Inspector’s Handbook,”

volume 2, chapter 4, paragraph 297, states that the purpose of surveillance of each foreign

air carrier, its aircraft, and its operations is to determine compliance, on a recurrent or

rotating basis, with the FARs and the foreign carrier’s operations specifications.

According to the FAA order, surveillance is conducted if a foreign carrier experiences “a

series of accidents, incidents, violations, or complaints (that relate to safety.)” The

surveillance includes any “R” (required) items specified in national program guidelines

and can also include routine and unannounced ramp inspections.

112 Annex 6 addresses the standards and recommended practices for operation of aircraft.

113 The position title for POIs assigned to foreign carriers is International Geographic Inspector

(Operations).
Factual Information 75 Aircraft Accident Report

Paragraph 297 of the FAA order also states that routine and unannounced ramp

inspections of a foreign air carrier conducting operations with foreign-registered aircraft

should be limited to those operations being conducted in the United States. The paragraph

also states that the inspections should include the following items: aircraft markings;

airworthiness, registration, and crewmember certificates; air traffic compliance; taxi and

ramp and passenger enplaning/deplaning procedures; baggage and cargo (especially

hazardous cargo); and compliance with the pilot-in-command age 60 policy, which states

that a flight crewmember is prohibited from acting as pilot-in-command if he or she has

reached age 60.

According to the FAA, the only “R” item required for Korean Air is one annual

ramp inspection. The FAA indicated that, since 1996, Korean Air received about

201 operations inspections, 129 maintenance inspections, and 48 avionics inspections.

1.17.6.2.1 International Aviation Safety Assessment Program 

The FAA established the International Aviation Safety Assessment (IASA)

program in August 1992 in response to concerns114 about the adequacy of surveillance

provided to foreign air carriers.115 According to an overview of the program posted on the

FAA’s Web site, the IASA is a foreign assessment program that “focuses on a country’s

ability, not the [ability of an] individual air carrier, to adhere to international standards and

recommended practices for aircraft operations and maintenance established by [ICAO].”

The overview indicated that “[t]he purpose of the IASA is to ensure that all foreign air

carriers that operate to or from the United States are properly licensed and [are provided]

safety oversight [ ] by a competent Civil Aviation Authority (CAA) in accordance with

ICAO standards.”116 According to the overview:

A foreign air carrier of a sovereign state desiring to conduct foreign air

transportation operations into the United States files an application with the DOT

[Department of Transportation] for a foreign air carrier permit under the Federal

Aviation Act,...at 49 U.S.C. 41302.... Consistent with international law, certain

safety requirements for operations into the United States are prescribed by the

FAA's Part 129 regulations (14 CFR part 129). 14 CFR Part 129 specifies that the

carrier must meet the safety standards contained in Part 1 (International

Commercial Air Transport) of Annex 6 (Operations of Aircraft) to the Convention

on International Civil Aviation (Chicago Convention). Before DOT issues a

foreign air carrier permit, it notifies the FAA of the application and requests the

114 One accident that raised such concerns was the January 25, 1990, crash of an Avianca Boeing 707 in

Cove Neck, New York, as a result of fuel exhaustion.

115 According to the FAA, about 600 foreign air carriers operate into the United States, and about

103 countries or regional country alliances have oversight responsibilities for air carriers that either operate

into the United States or have applied to operate into the United States. 

116 Paragraph 9.3.1 of ICAO Annex 6 states that operators “shall establish and maintain a ground and

flight training program . . . which ensures that all flight crew members are adequately trained to perform

their assigned duties. [The training program] shall also include training in knowledge and skills related to

human performance and limitations...[and] shall ensure that all flight crew members know the functions for

which they are responsible and the relation of those functions to the functions of other crew members.”
Factual Information 76 Aircraft Accident Report

FAA’s evaluation of the respective CAA’s capability for providing safety

certification and continuing oversight for its international carriers.

Upon DOT notification of a pending foreign air carrier application, if the FAA has

not made a positive assessment of that countr[y’]s safety oversight capabilities,

the FAA Flight Standards Service will direct its appropriate international field

office to schedule an FAA assessment visit to the CAA of the applicant’s country.

Once the assessments visits have been completed, the FAA assessment team will

return to the United States to compile the findings. Appropriate notifications to

the CAA and other U.S. Government officials of the results of the assessments

will be made from Washington, D.C., headquarters as soon as possible. 

If a CAA is found to be meeting its minimum safety obligations under the

Chicago Convention, the FAA will forward a positive recommendation to DOT. If

there is a pending foreign carrier application, DOT will issue the requested

economic authority and FAA will issue operations specifications to permit the

carrier to begin operations to or from the United States.

When CAA's of countries with existing air carrier service to the U.S. are found to

not meet ICAO standards, the FAA formally requests consultations with the CAA.

The purpose of consultations is to discuss [the FAA’s] findings in some detail and

explore means to quickly rectify shortcomings found with regard to ICAO

annexes, to enable its air carriers to continue service to the United States. During

the consultation phase, foreign air carrier operations from that country into the

United States will be frozen at existing levels.[117] FAA may also heighten its

surveillance inspections (ramp checks) on these carriers while they are in the

United States. If the deficiencies noted during consultations cannot be

successfully corrected within a reasonable period of time, FAA will notify DOT

that carriers from that country do not have an acceptable level of safety oversight

and will recommend that DOT revoke or suspend its carriers economic operating

authority. 

When CAA's of countries with no existing air carrier service to the United States

are found to not meet ICAO standards, the FAA does not, of course, undertake

consultations. The FAA will notify DOT that the CAA does not have an

acceptable level of safety oversight and its application for economic authority will

be denied. The FAA will undertake a reassessment of the CAA after evidence of

compliance with ICAO provisions has been received. FAA will, of course, be

willing to meet with CAA’s at any time, as [ ] resources permit. 

After the assessment visit, consultations (if necessary), and notifications have

been completed, the FAA will publicly release the results of these assessments.

The FAA plans to periodically revisit CAA's of countries with air carriers

operating into the United States to maintain full familiarity of the methods of that

country’s continued compliance with ICAO provisions. The FAA may also find it

necessary to reassess a CAA at any time if it has reason to believe that minimum

ICAO standards are not being met.

117 This policy is defined in a notice published in the Federal Register, Volume 60, No. 210, October 31,

1995.
Factual Information 77 Aircraft Accident Report

DESIRED OUTCOME: The FAA is working to determine that each country

meets its obligations under ICAO and to provide proper oversight to each air

carrier operating into the U.S. The continued application of this program will

result in a lower number of safety-related problems, including accidents,

incidents, and an improved level of safety to the flying public. 

The FAA established three ratings for the status of countries at the time of the

assessment. These categories and their definitions are as follows:

• Category I—Does Comply with ICAO Standards: A country’s civil aviation

authority has been assessed by FAA inspectors and has been found to license

and oversee air carriers in accordance with ICAO aviation safety standards.

• Category II—Conditional: A country’s civil aviation authority in which FAA

inspectors found areas that did not meet ICAO aviation safety standards and

the FAA is negotiating actively with the authority to implement corrective

measures. During these negotiations, limited operations by this country’s air

carriers to the U.S. are permitted under heightened FAA operations inspections

and surveillance.

• Category III—Does Not Comply with ICAO Standards: A country’s civil

aviation authority found not to meet ICAO standards for aviation oversight.

Unacceptable ratings apply if the civil aviation authority has not developed or

implemented laws or regulations in accordance with ICAO standards; if it

lacks the technical expertise or resources to license or oversee civil aviation; if

it lacks the flight operations capability to certify, oversee and enforce air

carrier operations requirements; if it lacks the aircraft maintenance capability

to certify, oversee and enforce air carrier maintenance requirements; or if it

lacks appropriately trained inspector personnel required by ICAO standards.

Operations to the U.S. by a carrier from a country that has received a Category

III rating are not permitted unless they arrange to have their flights conducted

with a duly authorized and properly supervised foreign air carrier appropriately

certified from a country meeting international aviation safety standards. 

During a June 17, 1999, briefing to Safety Board staff, the FAA indicated that,

although the IASA program is intended to determine whether a foreign country’s CAA is

providing adequate oversight, the program does not directly assess whether foreign

carriers are receiving such oversight or are complying with the provisions of Annex 6 to

the Convention on International Civil Aviation. The FAA assessment team does not

conduct surveillance of foreign air carriers; rather, it collects information and evaluates a

foreign CAA’s compliance with Annex 6 standards in seven areas: aviation law; aviation

regulations; CAA structure; technical inspector workforce; technical guidance; records of

certification; and records of surveillance, including followup and corrective actions.118

The country must be found to meet ICAO Annex 6 standards in all seven areas to be rated

as Category I. The FAA offers assistance to those countries that, according to its

evaluation, do not comply with ICAO Annex 6.
Factual Information 78 Aircraft Accident Report

The FAA also indicated that it has completed all of its initial assessments and that

the IASA program would soon transition to “Phase 2,”119 which will focus on review and

validation of the initial ratings and continued evaluation of the safety compliance

capability of foreign CAAs. According to the FAA, Phase 2 will be accomplished by

reviewing each country’s rating and all available information relevant to ICAO safety

oversight requirements at least every 2 years. However, the FAA indicated that it would

reevaluate a country that has air carriers operating into the United States any time there is

reason to question whether that country is meeting its international safety oversight

obligations.

According to the FAA, Phase 2 rating decisions will be based on information

gathered by the FAA, either during an on-site visit or through a questionnaire directed to

the foreign CAA, or the results of an assessment by another qualified entity, such as

ICAO. Also, the FAA intends to eliminate the Category III rating as part of Phase 2;

accordingly, countries found not to comply with ICAO Annex 6 will be rated as Category

II regardless of whether that country is conducting operations into the United States.

The KCAB was initially assessed in 1996 and was given a Category I rating. As of

October 1999, the KCAB had not been reassessed.

1.17.6.3 Department of Transportation Audit Report on Aviation Safety 

Under International Code Share Agreements

On September 30, 1999, the Department of Transportation Office of Inspector

General (DOT/IG) issued a report, titled Aviation Safety Under International Code Share

Agreements (Report No. AV-1999-138). The report noted that the number of international

code share agreements has more than tripled in the last 5 years and that U.S. carriers are

increasingly entering into such agreements with carriers from regions of the world where

aviation oversight and safety records are not as strong as those of the United States. The

report found that the current process by which code share agreements are approved by the

DOT does not adequately address safety implications and that the “FAA has not taken an

active role in the approval or safety oversight of international code share agreements,

either before or after approval.” Specifically, the DOT/IG report stated:

FAA limits its input to advising [the Office of the Secretary of Transportation

(OST)] about whether a foreign carrier’s homeland, as distinguished from the air

carrier involved, has procedures to exercise oversight of its carriers in compliance

with international safety standards. FAA staff stated that if they become aware of

adverse safety information about a foreign carrier, they will pass that on as well;

118 The FAA does not assess a country’s compliance with Annex 13. The Safety Board notes that, during

the Accident Investigation Group (AIG) divisional meeting held by ICAO from September 14 to 24, 1999,

AIG delegates adopted a recommendation for the ICAO Council to take steps to expand the ICAO safety

oversight audit program to include an assessment of a country’s compliance with Annex 13. The program

currently assesses a country’s compliance with Annexes 1, 6, and 8.

119 The FAA indicated that, in August 1998, the agency’s Administrator had approved the transition to

Phase 2 but that the change would not take effect until publication of a notice in the Federal Register.
Factual Information 79 Aircraft Accident Report

however, they were able to provide only one example of this kind of advice, and

the effort made to assess safety implications appears to be nonexistent.

[The DOT/IG’s] review found that the Department’s current procedures require

nothing of the U.S. or foreign carrier that will be parties to the agreement about

the foreign carrier’s safety. FAA performs no trend or other analysis, and makes

no recommendations to OST, as to whether it is satisfied that there are no negative

safety implications relative to the foreign carrier that will be involved in the code

share agreement....

The DOT/IG’s report evaluated the FAA’s explanation for its limited oversight role

in code share agreements. The report made the following three points:

First, FAA says it is without legal authority to make safety fitness determinations

regarding individual foreign carriers. This view has merit. However, the legal

situation is quite different when, as here, a U.S. carrier seeks U.S. approval to hold

out to the public flights on a foreign aircraft as if they were U.S. flights and to

ticket such flights in the name of a U.S. carrier. Furthermore, Federal law requires

that “safety” be a paramount consideration in deciding whether to approve

agreements like code shares.

Second, FAA correctly points out that it does make determinations [through the

IASA program] about the civil aviation authority in the foreign carrier’s

homeland. This program identifies whether the carrier’s homeland provides

adequate aviation oversight of its carriers, and has improved international aviation

safety by helping foreign civil aviation authorities improve their oversight.

However, this is quite different from a judgment about the safety practices of an

individual carrier. FAA is itself a civil aviation authority that meets international

standards, but that is materially different from a conclusion that all U.S. carriers

therefore follow sound safety practices.

The third and most legitimate point FAA raises is that it has limited resources and

already is resource-constrained in exercising oversight of U.S. aircraft and U.S.

crew operations. Adding code share agreements to the workload would be an

additional burden and raise expectations. We believe the answer to this is that U.S.

carriers seeking approval for a code share agreement can reasonably be expected

to perform most of the work and provide FAA assurances that the foreign carrier

that will operate as a U.S. flight is compliant with applicable safety requirements.

FAA’s role would be to ensure that U.S. carriers have a credible process in place to

provide such assurances.

The Department of Defense (DOD) is one of the largest U.S. consumers of air

carrier services because of its need to transport military personnel to locations throughout

the world. According to the DOT/IG report, DOD’s policy has been to use U.S. carriers

for this transportation service, and DOD performs a safety review of a U.S. carrier before

it can be included on an approved list of authorized military air transport providers. The

report also indicated that the U.S. carriers proposed the use of foreign code share carriers

for providing military transportation. Because DOD must ensure the safety of foreign code

share carriers, it established a program in August 1999 with the Air Transport Association

and six U.S. airlines.120 Under this program, the six U.S. air carriers will perform (or will
Factual Information 80 Aircraft Accident Report

arrange to have a third party perform) safety assessments of their foreign code share

partners to ensure that those partners meet the legal criteria necessary to transport U.S.

military personnel. The DOT/IG found that the FAA could build on DOD’s program and

that the FAA must ensure that safety is “a condition of initial and continued approval for

international code share arrangements.”

The DOT/IG report made the following recommendations to the DOT and the FAA:

• Develop and implement procedures requiring that all U.S. carriers perform safety

assessments of foreign carriers as a condition of code share approval and continued

authorization. These procedures should include requirements that carriers:

• perform an initial on-site review of all existing, pending, and future code share

partners;

• establish review procedures, to be approved by FAA, that will address the content

of the assessments and qualifications of staff conducting the assessments;

• develop assessment processes that include review and verification that foreign

partners have implemented effective procedures in critical safety areas such as

maintenance operations, airworthiness of aircraft, crew qualifications, crew

training, flight operations, en-route procedures, emergency response plans,

security, and dangerous goods;

• provide copies of safety assessments to FAA for review and acceptance, and make

available to FAA, when necessary, information supporting assessment results;

• submit confirmations from senior safety officials that the assessment results were

satisfactory and any deficiencies noted have been corrected; and

• coordinate reviews to avoid multiple assessments of foreign carriers code sharing

with more than one U.S. partner.

• Coordinate closely with the Department of Defense to maximize the effective use of

limited resources between the two agencies, avoid duplication, and establish protocols

for the exchange of information about carrier safety assessments. FAA should also

consider the safety assessment results in performing IASA reviews.

• Establish procedures for terminating or restricting the use of code share agreements

when (1) the Department of Defense determines that adverse safety information

warrants prohibiting U.S. military personnel from using a foreign carrier, (2) the

U.S. carrier terminates the agreement, or (3) FAA, on its own initiative, makes a

similar determination regarding the transport of U.S. passengers.

The DOT/IG report also recommended that the FAA

• Develop oversight procedures for FAA to validate U.S. carriers’ safety assessment

programs. The validation should include:

120 According to the DOT/IG report, the six airlines are American, Continental, Delta, Northwest,

Trans World, and United.
Factual Information 81 Aircraft Accident Report

• reviews of air carriers’ audit procedures, assessment processes, and

documentation supporting review conclusions to ensure the consistency, quality,

and effectiveness of the review results; 

• comprehensive audits of a sample of safety assessments to confirm that carriers

have applied agreed upon standards and procedures in conducting the

assessments; and

• procedures to, if necessary, perform on-site inspection of aircraft used in code

share operations.

• Require that FAA staff perform risk assessments using available safety data on foreign

carriers and review results of air carrier safety assessments, if made available, as part

of its safety advice to OST on code share applications. This interim procedure should

be used no more than 3 months, until the Department finalizes new code share

procedures.121

1.18 Additional Information

1.18.1 Minimum Safe Altitude Warning System 

1.18.1.1 Postaccident Actions Taken by the Federal Aviation Administration

On August 15, 1997, the FAA announced in a press release that, as a “routine

precaution,” it had ordered MSAW testing and recertification after the Safety Board’s

investigation of the flight 801 accident raised questions about the MSAW’s performance.

The FAA reported that, of the 192 in-service122 MSAW software functions at radar

approach control facilities, all but 2 were found to be working properly. According to the

press release, the software functions were corrected, and all of the functions were

recertified as operating properly. 

Also, in response to inquiries from Safety Board staff, the FAA created special

teams of automation experts to completely examine all site adaptation parameters for the

192 MSAW systems located throughout the United States. The FAA directed ATC

managers at these locations to document and report any MSAW problems. 

Further, the FAA’s Associate Administrator for Air Traffic Services directed a factfinding review of MSAW equipment and operational procedures at 10 ATC towers The

review included a survey of 105 air traffic personnel and 33 airway facilities personnel.

121 The DOT/IG report indicated that a “code share team,” comprising representatives from the DOT and

the FAA, was developing recommendations to address many of the issues discussed in the audit report. The

report noted that, once the recommendations are accepted by DOT and FAA management, additional time

and effort would be required to develop policies and procedures to implement those recommendations.

122 The FAA indicated that one MSAW function—at the Aspen/Pitkin Airport in Colorado—was not in

service because of the “large number of false low-altitude alerts in the mountainous terrain.” The FAA also

indicated that “aviators have been notified of this condition.”
Factual Information 82 Aircraft Accident Report

According to the FAA’s executive summary of the MSAW fact-finding review

(dated September 1997), “air traffic staff and operational personnel, except for those with

automation training, claimed little knowledge of the parameters or components that make

up MSAW.” The executive summary indicated that very few of the air traffic survey

respondents could remember receiving facility training about different MSAW areas and

that most reported that their only MSAW training was an overview during the initial air

traffic course.

According to the executive summary, the air traffic survey respondents indicated

that a check of the MSAW aural alarm was required at the beginning of each shift, but they

gave varying answers concerning what should be done if the MSAW was not functioning

properly. Likewise, these survey participants believed that controllers should issue an

advisory if an aircraft generates an MSAW alert, but the participants were not consistent in

their answers regarding who was responsible for responding to the MSAW alert at a

satellite tower. In addition, the air traffic personnel in the survey gave different answers

regarding who had the authority to adjust MSAW parameters and “vague” answers

regarding MSAW general notices.

All of the airways facilities personnel in the survey indicated that daily functional

checks of aural MSAW alarms were required, and they knew where this check was

documented. However, these personnel gave varying answers concerning how they would

complete the check if an MSAW system were inhibited. Further, these respondents

indicated that their MSAW training ranged from initial hardware training and on-the-job

training to only on-the-job training for those personnel who completed initial schooling

before the MSAW system was implemented.

The fact-finding review also found that the ARTS IIA and IIIE parameter

documentation was unclear and confusing to automation specialists and that there were

“no guidelines or standards defined in any document concerning the proper way to adapt

the MSAW site variables.” The survey revealed that, as a result of inadequate reference

material, the MSAW altitudes at one ATC tower and two TRACONs were set incorrectly.

These facilities had adapted the MSAW approach path monitor altitudes to be agl values

when the system was intended to provide msl values. As a result, all the altitudes used for

the MSAW system were hundreds of feet too low at the ATC tower and one of the

TRACON facilities; the altitude discrepancy at the other TRACON was “negligible”

because of its approximate sea level elevation. 

On the basis of its fact-finding review, the FAA made several internal

recommendations, including the following: 

• a standardized comprehensive training program should be established to

provide a basis for entry-level and periodic refresher training in the operation

and maintenance of MSAW equipment, and a certification process should be

established for personnel who have completed this training;

• uniform site adaptation/system parameters should be established for MSAW

equipment operation; 
Factual Information 83 Aircraft Accident Report

• provisions for periodic evaluation of MSAW equipment should be established

to ensure system integrity and reliability; and 

• configuration management of all software should be reflected in appropriate

documents and centrally controlled.

In addition, in an October 1997 briefing to Safety Board investigators, FAA

officials presented the agency’s planned corrective actions for the national MSAW system.

The officials stated that the FAA was developing a central oversight process for the

MSAW program and that MSAW systems would be flight checked and ground certified as

part of the commissioning process for a new radar and then periodically thereafter.

Further, the officials said that the FAA had approved a new MSAW software management

policy that “established strict management oversight and control” for MSAW software

modifications. 

1.18.1.2 Previous Safety Board Recommendations on the 

Minimum Safe Altitude Warning System

The Safety Board has issued numerous safety recommendations regarding the

MSAW system. Recent MSAW safety recommendations have addressed the installation of

MSAW equipment in VFR terminal facilities that receive radar information from a host

radar control facility (as is the case with the Agana tower), as well as the inspection and

testing of MSAW speakers to ensure the integrity of MSAW systems. 

Development of an MSAW System (A-73-46)

On December 29, 1972, Eastern Air Lines flight 401, a Lockheed L-1011,

N310EA, crashed near Miami, Florida. In its final report,123 the Safety Board stated that its

investigation

...revealed another instance where the ARTS III system conceivably could have

aided the approach controller in his ability to detect an altitude deviation of a

transponder-equipped aircraft, analyze the situation, and take timely action...to

assist the flight crew. In this instance, the controller, after noticing on his radar

that the alphanumeric block representing flight 401 indicated an altitude of

900 feet, immediately queried the flight as to its progress. An immediate positive

response from the flight crew, and the knowledge that the ARTS III equipment, at

times, indicates incorrect information for up to three scans, led the controller to

believe that flight 401 was in no immediate danger.

As a result of its findings, the Safety Board issued Safety Recommendation

A-73-46, which asked the FAA to 

123 National Transportation Safety Board. 1973. Eastern Air Lines, Inc. L-1011, N310EA, Miami,

Florida, December 29, 1972. Aircraft Accident Report NTSB/AAR-73/14. Washington, DC.
Factual Information 84 Aircraft Accident Report

Review the ARTS III program for the possible development of procedures to aid

flight crews when marked deviations in altitude are noticed by an air traffic

controller. 

In a May 31, 1977, letter, the FAA advised the Safety Board that an MSAW system

had been developed as an integral function of the ARTS III program and that controllers

had received guidance on its use. On September 16, 1977, the Safety Board classified

Safety Recommendation A-73-46 “Closed—Acceptable Action.”

Minimizing MSAW Inhibited Areas (A-90-130)

On September 8, 1989, USAir flight 105, a 737-200, N283AU, struck four

electronic transmission cables while executing the localizer backcourse approach to

runway 27 at Kansas City International Airport in Kansas City, Missouri.124 The Safety

Board’s final report on this incident concluded that, although the Kansas City airport’s

ATC facility was equipped with MSAW software, the MSAW alert failed to activate

during the premature descent of flight 105 because the descent had occurred more than

1 mile from the runway threshold and inside an area that had been designed to inhibit the

MSAW to reduce false alerts. The Safety Board’s report said that “...this incident

indicates the need to revise the parameters controlling the size of the MSAW inhibit

areas.” The report urged the FAA “to provide site adaptations guidance to encourage

modification of MSAW parameters, as appropriate, to increase the MSAW protection

areas and to minimize the extent of inhibited areas.” On the basis of its findings, the Safety

Board issued Safety Recommendation A-90-130, which asked the FAA to

Provide site adaptation guidance to encourage modification of Minimum Safe

Altitude Warning parameters, as appropriate, to minimize the extent of inhibit areas.

In an October 6, 1993, letter, the FAA stated that it had issued a change to FAA

Order 7210.3K, “Facility Operation and Administration,” which provided for site

adaptation guidance to minimize the extent of MSAW inhibited areas. Because the FAA’s

response met the intent of Safety Recommendation A-90-130, it was classified “Closed—

Acceptable Action” on January 28, 1994.

MSAW Site Variables and Capture Boxes (A-94-187)

On June 18, 1994, a Transportes Aereos Ejecutivos, S.A. (TAESA) Learjet 25D,

operating under 14 CFR Part 129, was executing an ILS approach in IMC when the

airplane crashed 0.8 nm south of the runway 1R threshold at Dulles International Airport,

Chantilly, Virginia.125 The 2 flight crew members and all 10 passengers were killed. The

Safety Board’s investigation determined that the accident airplane did not generate any

124 National Transportation Safety Board. 1990. USAir Flight 105, Boeing 737-200, N283AU, Kansas

City International Airport, Missouri, September 8, 1989. Aircraft Accident Report NTSB/AAR-90/04.

Washington, DC.

125 National Transportation Safety Board, Controlled Collision With Terrain, Transportes Aereos

Ejecutivos, S.A. (TAESA), Learjet 25D, XA-BBA, Dulles International Airport, Chantilly, Virginia, June 18,

1994. Aircraft Accident Report NTSB/AAR-95/02. Washington, DC. 
Factual Information 85 Aircraft Accident Report

MSAW alerts while on the approach to the airport. The investigation also determined that

the MSAW site variable parameters at the airport required two “current position” radar

returns or three “predicted position” radar returns below the 500-foot floor before the

aural and visual alerts would activate. A review of the radar data revealed that the airplane

generated one radar return below the alert altitude of the runway 1R MSAW capture box. 

The Safety Board’s investigation of this accident revealed discrepancies with the

airport’s MSAW equipment.126 Specifically, the MSAW site variable parameters for

runway 1R indicated a discrepancy between the MSAW-defined runway location and the

actual threshold location. The FAA said that, when the ARTS III software was

programmed for a 10° west variation (the angular difference between true north and

magnetic north at Dulles Airport), the computed position for the runway threshold did not

correlate to the actual geographic runway location. Further, the “radar-established”

runway position was 700 feet northeast of the actual runway threshold. The Safety Board

found that the error in the radar position for the runway 1R threshold resulted in a similar

displacement of the radar MSAW capture box from its intended position with the actual

approach path to runway 1R. The Safety Board concluded that such displacement might

compromise the protective intent of the MSAW system. 

On November 21, 1994, the Safety Board issued Safety Recommendation

A-94-187, which asked the FAA to 

Conduct a complete national review of all environments using MSAW systems.

This review should address all user-defined site variables for the MSAW

programs that control general terrain warnings, as well as runway capture boxes,

to ensure compliance with prescribed procedures.127

In a March 20, 1995, letter, the FAA stated that it planned to review the MSAW site

variables to ensure compliance with prescribed procedures. According to the FAA, the

126 The Safety Board investigated another accident involving discrepancies with an MSAW system. On

January 13, 1998, a Gates Learjet 25B, N627WS, operated by American Corporate Aviation, Inc., of

Houston, Texas, crashed approximately 2 nm east of the runway 26 threshold at George Bush

Intercontinental Airport in Houston, Texas, during an ILS approach. (See Brief of Accident FTW98MA096

for more information.) The investigation revealed, among other things, that the MSAW system at the airport

was not configured in accordance with the guidance provided in FAA technical document NAS-MD-633,

“Minimum Safe Altitude Warning.” The Board identified two MSAW-related errors: the altitude

computations for runway 26 were based on the ILS DH instead of the localizer-only MDA, and the ILS data

should not have been used at all because other nonprecision approaches to the runway were available. At the

time of the accident, the MSAW threshold altitude for runway 26 was incorrectly set to 100 feet agl. Proper

application of the procedures contained in NAS-MD-633 would have resulted in a threshold setting of 402

feet agl. This accident is also included in the discussion of Safety Recommendations A-95-35 and A-99-36

in section 1.18.2.4. 

127 The Safety Board also issued Safety Recommendation A-94-186, which asked the FAA to review the

calculations establishing the runway threshold coordinates for all runways at Dulles International Airport

with respect to the air surveillance radar to verify proper alignment of the MSAW capture boxes. On

November 20, 1995, the Safety Board noted that the FAA had completed its review of the calculations and

adaptation values for runway threshold coordinates for all runways at the airport and had verified proper

alignment of the capture boxes. Therefore, Safety Recommendation A-94-186 was classified “Closed—

Acceptable Action.”
Factual Information 86 Aircraft Accident Report

review would address all user-defined site variables for the MSAW program that control

general terrain warnings, as well as runway capture boxes, to ensure compliance. The FAA

stated that its review of 190 ATC facilities (128 operational ARTS IIA and 62 operational

ARTS IIIA sites) would begin in April 1995 and be concluded by July 1995. On

November 20, 1995, the Safety Board stated its concern that the FAA’s review process for

the 190 ATC facilities with MSAW was taking longer than originally anticipated. 

On January 26, 1996, the FAA stated that it had completed its review of the

190 ATC facilities. Further, the FAA stated that, as of October 1995, proper alignment of

the MSAW capture boxes had been verified at all 128 ARTS IIA and 62 ARTS IIIA

sites.128 On April 8, 1996, the Safety Board stated that, because this action met the intent

of Safety Recommendation A-94-187, it was classified “Closed—Acceptable Action.”

MSAW Aural Alerts in VFR Facilities (A-95-120)

On January 29, 1995, a Beechcraft A36 crashed during a missed ILS approach to

DeKalb-Peachtree Airport in Chamblee, Georgia.129 The pilot, the sole occupant of the

flight, was killed. The Safety Board determined that, before the accident, the airport tower

had received four MSAW general terrain warning alerts from the Atlanta TRACON,

which was providing approach control services. The tower was equipped with a D-BRITE

radar display with visual MSAW alerting only.130

The Safety Board’s investigation found that, if a full MSAW system (including an

aural alert) had been installed in the DeKalb-Peachtree tower, the controller would have

received an aural MSAW alert along with the visual alert that had been depicted on the

radar. Further, the tower controller told Board investigators that he did not observe the

visual MSAW alert on the D-BRITE because he had been involved with other duties

before the accident that did not allow him to continually monitor the data block for the

airplane.

As part of its investigation into the accident, on February 8, 1995, the Safety Board

requested that the FAA provide its policy on installation of aural MSAW alerts at

low-density ATC towers equipped with D-BRITE radar displays. On June 27, 1995, the

FAA stated that “...no policy exists for the operation of an aural alarm associated with

MSAW in VFR towers that are not combined with full radar approach control facilities.”

On November 30, 1995, the Safety Board issued Safety Recommendation

A-95-120, which asked the FAA to

128 According to FAA inspection records, the Guam CERAP ARTS IIA facility was reviewed in July

1995.

129 See Brief of Accident ATL95FA046 for more information.

130 FAA Order 7110.65, “Air Traffic Control,” states that “...unless otherwise authorized, tower radar

displays are intended to be an aid to local controllers in meeting their responsibilities to the aircraft operating

on the runways or within the surface area.” The order also states that “...local controllers at non-approach

control towers must devote the majority of their time to visually scanning the runways and local area; an

assurance of continued positive radar identification could place distracting and operationally inefficient

requirements upon the local controller.”
Factual Information 87 Aircraft Accident Report

Within 90 days from the receipt of this letter, develop a policy that would require

the installation of aural minimum safe altitude warning (MSAW) equipment in

those visual flight rules terminal facilities that receive radar information from a

host radar control facility and would otherwise receive only a visual MSAW alert.

On February 21, 1996, the FAA stated that it would conduct a cost-benefit analysis

to determine the feasibility of implementing this safety recommendation. The FAA further

stated that the analysis would be completed by the end of March 1996. In June 1996, the

FAA completed the cost-benefit analysis and determined that it was feasible to implement

the recommendation. The FAA expected that implementation would be accomplished by

the end of March 1997. 

In its July 15, 1996, letter to the FAA, the Safety Board stated that, although the

FAA’s implementation of the requirement for the aural alert was not accomplished within

the 90 days specified in the safety recommendation, the Board was pleased that the FAA

had proceeded with the implementation. The Board indicated that it would wait to receive

a list of the affected facilities and anticipated installation dates.

On July 31, 1997, the FAA stated that it had conducted a survey to determine the

total number of ATC facilities that did not have aural MSAW alerts installed. The FAA

found that 43 remote displays had been equipped with aural alarms but that 69 remote

displays did not have aural alarms. The FAA anticipated that the aural alarms at those

69 remote displays would be implemented by February 1998. 

On December 30, 1997, the Safety Board said that it was encouraged that the FAA

was moving forward and urged the FAA to keep the program on track and within its

anticipated milestones. On May 14, 1998, the FAA said that, as of April 10, 1998, kits had

been delivered to all 69 remote sites and that all alarms would be operational during May

1998. However, at the Safety Board’s public hearing in March 1998, the FAA’s Deputy

Director for Air Traffic Operations testified that the new projected completion date for

installation of aural alarms at VFR towers, including the tower at Guam, was April 2000.

On October 19, 1998, the Safety Board stated that the primary intent of this

recommendation was to ensure that VFR tower controllers who have a visual

representation from a distant host radar receive an aural alert when aircraft under their

control and with whom they are in radio communication descend below the minimum safe

altitude. If the tower controller was engaged in visually scanning for other aircraft, the

aural alert would allow the controller to determine the aircraft call sign and transmit the

appropriate warning to the pilot. The Board’s letter indicated that the FAA was unclear

about whether controllers at VFR terminal facilities would receive an aural alert for those

aircraft with whom they are in communication. Further, Safety Board staff had determined

that, in at least one location, the VFR tower would not receive an aural warning. (The

Board’s letter did not identify the location of this facility.) The Board requested that the

FAA ensure that controllers at all VFR towers with visual representation systems from a

distant host radar receive an aural alert when aircraft within their traffic pattern and with

whom they are in communication descend below the minimum safe altitude. Pending the
Factual Information 88 Aircraft Accident Report

receipt of this information from the FAA, Safety Recommendation A-95-120 was

classified “Open—Acceptable Response.”

On September 29, 1999, a representative from the FAA stated that the agency’s

management had indicated that the Agana tower was currently receiving aural MSAW

alerts. At an October 7, 1999, briefing attended by the FAA Administrator, the Safety

Board Chairman, and staff from both agencies, the FAA indicated that 69 MSAW aural

alarms had been delivered and that 51 alarms were to be delivered. The FAA expected that

the acquisition of these 51 alarms would be completed by October 2000 and that their

installation in VFR towers would be completed by April 2001.

On October 12, 1999, the FAA Program Director for Serco Aviation Services told

Safety Board staff that the Agana tower has the capability to receive an aural MSAW alert

but that, unless the Guam CERAP transfers responsibility for the aircraft’s data block, the

tower will not receive the aural warning. The official added that the CERAP does not

currently transfer responsibility for the aircraft’s data block to the Agana tower; therefore,

the tower does not receive an aural MSAW alert.

On October 14, 1999, the FAA Program Director for Air Traffic Operations

confirmed that Agana tower was not receiving aural MSAW alerts. In an October 15,

1999, facsimile, the program director indicated that the Agana tower “has the software and

hardware capability in place to receive aural alarms.” The director further indicated that

the FAA had issued a policy “to ensure that the facility that is in direct radio

communications with the aircraft receives the aural alarm” and that the policy would

become effective by November 15, 1999. (The FAA subsequently indicated that, under the

new procedures, the Guam CERAP would transfer responsibility for the aircraft’s data

block to the Agana tower and that the aural MSAW alert would be transferred to the tower

upon its acceptance of the transfer of the data block. The tower would advise the CERAP

after an MSAW alert was issued.) The program director stated, in a followup telephone

conversation with the Safety Board’s Director of the Office of Aviation Safety, that a

national policy would be issued to ensure that procedures similar to those being

implemented at Guam are followed at other VFR towers. 

On October 25, 1999, the FAA indicated that the MSAW aural alarms for the

ARTS IIA system at Guam were reconfigured on October 24, 1999. The FAA stated that,

in the event of a low-altitude alert for an aircraft operating in the vicinity of Guam

International Airport, aural alarms will be simultaneously generated at the CERAP and the

Agana tower, along with visual low-altitude alerts on the radar displays at both facilities. 

On November 2, 1999, the Safety Board received a copy of draft FAA Notice

N7210.485, “Minimum Safe Altitude Warning for Remote Tower Displays.” According to

the notice, facility managers at ATC towers that have aural alarms for MSAW are to

ensure that “the operational support facility has adapted the software functionality to

ensure the aural alarms operate in the ATCT [air traffic control tower]” and that “aural

alarms are received in the ATCT upon transfer of communications.” The FAA indicated

that the effective date for this notice would be February 1, 2000. 
Factual Information 89 Aircraft Accident Report

The Safety Board’s evaluation and classification of Safety Recommendation

A-95-120 are discussed in section 2.6.2. 

Inspections and Tests of MSAW Speakers and the Standard Terminal

Automation Replacement System Program (A-97-22 Through A-97-27)

On October 2, 1996, a Piper PA-32-300, N2881W, crashed in a heavily wooded

area in Brandywine, Maryland, while on approach to Washington Executive/Hyde Field

Airport in Clinton, Maryland.131 The pilot and two passengers were killed, and the

airplane was destroyed. According to MSAW data retrieved from the Washington National

TRACON, the accident airplane generated four general terrain warning MSAW alerts

during the approach to the airport. A controller-in-training and a fully certified instructor

were providing ATC services to the accident airplane from the TRACON’s F-2 radar

position. In a postaccident interview, both controllers stated that they did not recall seeing

or hearing any MSAW alerts. Several other controllers and a supervisor who were

stationed at nearby positions about the time of the accident also stated that they did not

recall hearing or observing any low-altitude warnings before the accident.

As part of the Safety Board’s investigation of this accident, a Board investigator

toured the TRACON radar room to observe the control position that provided ATC

services to the accident pilot. During this tour, the investigator noted that the MSAW aural

alarm speaker, located directly above the F-2 radar position (and the only MSAW speaker

in the radar room), was covered with heavy paper held in place with what appeared to be

masking tape.

On the basis of its findings during this accident, the Safety Board issued Safety

Recommendations A-97-22 through -27 on April 16, 1997. Safety Recommendations

A-97-22 and -23 asked the FAA to

Immediately issue an urgent general notice to all affected air traffic managers,

directing them to conduct an immediate visual inspection and aural test of the

aural minimum safe altitude warning speakers in their facilities to ensure that no

devices have been placed over them that might hinder, mute, or prevent the aural

warning from being heard in the operational quarters. (A-97-22)

Require that a daily visual inspection and aural test of the minimum safe altitude

warning (MSAW) speakers located in the operational quarters be conducted by

supervisory personnel prior to the start of each shift to ensure the integrity of the

MSAW system. Require that these inspections be recorded in the appropriate

facility logs. (A-97-23) 

On July 1, 1997, the FAA stated that it agreed with the intent of Safety

Recommendations A-97-22 and -23. The FAA stated that, on May 7, 1997, it had ordered

air traffic division managers to brief facility managers on the issue of muted MSAW

speakers and instructed supervisors to conduct a visual inspection of MSAW speakers and

remove “any muting devices” from these speakers. In addition, the FAA issued a general

131 See Brief of Accident IAD97FA001 for more information.
Factual Information 90 Aircraft Accident Report

notice on June 7, 1997, to implement the requirement for supervisors to check the MSAW

speakers as part of the shift checklist and record the completion of this inspection on the

appropriate facility logs. The FAA also revised Order 7210.3, “Facility Operation and

Administration,” to reflect the change in policy and procedures.

On February 27, 1998, the Safety Board stated that, because the actions taken by

the FAA addressed the intent of Safety Recommendations A-97-22 and -23, they were

classified “Closed—Acceptable Action.” 

Safety Recommendation A-97-24 asked the FAA to

Require that all affected terminal personnel be briefed on the contents of this

safety recommendation letter. This briefing should focus on generating awareness

and vigilance in those situations in which a safety alert might occur and

controllers must be prepared to respond, as directed in FAA Order 7110.65, “Air

Traffic Control.”

On July 1, 1997, the FAA stated that it complied with this safety recommendation

in a June 9, 1997, memorandum to facility managers, requiring that controllers be briefed

on how to respond to MSAW alerts. The facility managers were directed to ensure, within

2 weeks after the receipt of the memorandum, that all operational personnel were briefed

on the requirements of FAA Order 7110.65, “Air Traffic Control,” paragraph 2-1-1, “Duty

Priority;” 2-1-6, “Safety Alerts;” and 5-15-57, “Inhibiting Minimum Safe Altitude

Warnings (MSAW).” All operational personnel were also expected to be briefed on the

actions to be taken when controllers are alerted by the MSAW of an aircraft’s proximity to

terrain.

On February 27, 1998, the Safety Board stated that it had received a copy of the

FAA’s June 9, 1997, memorandum but that, in light of the Korean Air flight 801 accident

on August 6, 1997, the Board had not received written confirmation that the actions

directed by the memorandum were completed for the Guam ATC facilities. On September

25, 1998, the FAA stated that it had accomplished the briefing to Guam ATC facility

personnel on July 18, 1997. As a result, the Safety Board classified Safety

Recommendation A-97-24 “Closed—Acceptable Action” on January 14, 1999. 

Safety Recommendation A-97-25 asked the FAA to 

Modify the software for the minimum safe altitude warning system to enhance

conspicuity of those aircraft that may require the controller’s immediate attention

and action. Such modifications might be accomplished by placing the target and

data block within a flashing circle.

The FAA stated in its July 1, 1997, letter that it reviewed the feasibility of

modifying the software for the MSAW system to enhance the conspicuity of the data

block. The FAA concluded that the existing MSAW processing generated sufficient

alarms and was completely adequate; thus, no further action would be necessary.
Factual Information 91 Aircraft Accident Report

On February 27, 1998, the Safety Board stated that it was disappointed with the

FAA’s response to this safety recommendation and the FAA’s continued belief that the

design of the current MSAW visual display is adequate. Further, the Safety Board stated

that the evidence in the Brandywine, Maryland, accident clearly demonstrated that

multiple MSAW visual and aural warning alerts were generated in the operational quarters

of the TRACON but that the controller failed to respond to these alerts. The Safety Board

believed that the FAA should reconsider its position not to remedy the deficiencies that led

to the issuance of this recommendation. 

On September 25, 1998, the FAA stated that color displays, now under

development for the Standard Terminal Automation Replacement System (STARS),

would provide the increased conspicuity suggested in this safety recommendation.

According to the FAA, the STARS early display configuration initial operational

capability was scheduled for Ronald Reagan Washington National Airport in March 1999,

and the early display configuration operational readiness demonstration was scheduled for

June 1999. The early display configuration was to include the color red for alerts in

addition to flashing data blocks. All ARTS data, except for alerts, would be monochrome.

On January 14, 1999, the Safety Board stated that, pending the commissioning of

STARS and the FAA’s inclusion of the flashing red MSAW display feature in the system’s

final operational configuration, Safety Recommendation A-97-25 was classified “Open—

Acceptable Response.” 

On August 13, 1999, the FAA stated that the delivery of STARS had been delayed.

The FAA indicated that, on April 26, 1999, it announced a revised plan for the STARS

program. According to the revised plan, the STARS early display configuration (which

includes existing MSAW capability) is to begin initial operations at Syracuse, New York,

and El Paso, Texas, in December 1999 and January 2000, respectively. Also, the FAA

stated that, as part of the revised plan, it would procure ARTS color displays (which

display the alert data blocks in flashing red) for the largest TRACONs and any new

facilities while STARS development continues. The ARTS color displays are scheduled to

begin operations at the New York TRACON in August 2000.

The FAA indicated that, when the STARS full-service system is deployed, the

MSAW alerts will flash in red. However, the FAA stated that it did not plan to modify the

existing MSAW system as requested in this safety recommendation because the existing

system provides both aural and visual alarms and is completely adequate when operated

according to design.

On November 3, 1999, the Safety Board stated that it was deeply concerned about

the significant delay in fielding STARS and that it could not continue to maintain the

classification of this recommendation, which was evaluated to be “Open—Acceptable

Response” in January 1999, if the implementation of STARS according to its current

schedule was the FAA’s only means for complying with the recommendation. The Board

urged the FAA to expedite the implementation of STARS by significantly accelerating the

current schedule. The Board also urged the FAA to reconsider its position on modifying

existing MSAW software if the STARS implementation schedule cannot be accelerated.
Factual Information 92 Aircraft Accident Report

Pending the FAA’s reconsideration of this issue or a change in the implementation

schedule for STARS, Safety Recommendation A-97-25 remained classified “Open—

Acceptable Response.” 

Safety Recommendation A-97-26 asked the FAA to

Require that the Standard Terminal Automation Replacement System program

include a minimum safe altitude warning (MSAW) speaker at each radar display, a

capability for the controller to momentarily override and mute an MSAW alert,

and a computerized recording of the muting of such an alert. 

On July 1, 1997, the FAA outlined the specifications for STARS and the MSAW

system. On February 27, 1998, the Safety Board stated its belief that, for those aircraft that

qualify under the MSAW system as part of the routine ATC services, the controller should

not be given the option to permanently inhibit the MSAW processing. The Board clarified

the intent of this safety recommendation by restating that the controller should be

permitted to temporarily mute an alert to acknowledge that warning was received and then

act on such an alert, if required. Further, the Board stated that, although the FAA provided

specifications regarding the STARS and MSAW system, it did not address the intent of the

recommendation. 

On September 25, 1998, the FAA said that STARS terminal controller

workstations and tower display workstations contained individual aural alarm speakers

and that STARS would permit MSAW alert inhibits for either a specified aircraft or

workstation. The FAA also stated that STARS was designed to permit temporary inhibits

resulting from specific aircraft operation characteristics or possible system malfunctions

and that all inhibit actions would be recorded. According to the FAA, STARS allows a

controller to silence a routine aural alert by hitting an “acknowledge” key. The FAA

indicated that, although the aural alarm would be silenced, the alert would remain

displayed until the violation condition ceased. 

On January 14, 1999, the Safety Board stated that, because STARS incorporated

all components suggested in Safety Recommendation A-97-26, it was classified

“Closed—Acceptable Action.”

Safety Recommendation A-97-27 asked the FAA to

Require, under the Standard Terminal Automation Replacement System program,

that minimum safe altitude warning alerts on instrument flight rules aircraft be

duplicated at a position in the operational quarters designated for supervisory

personnel and that the supervisor determine the validity of the alert and whether

appropriate corrective action has been initiated or is required.

The FAA’s July 1, 1997, letter indicated that there is no operational requirement

under STARS to duplicate MSAW alarms at supervisory positions. The FAA also stated

that supervisory positions did not include controller displays and that it did not plan to

provide displays to supervisory personnel. According to the FAA, STARS would provide
Factual Information 93 Aircraft Accident Report

a supervisor with the ability to monitor MSAW alerts immediately from every controller

position that displays an alert. 

On February 27, 1998, the Safety Board stated its understanding that the current

STARS operational documentation contained no requirement to duplicate the MSAW

alerts at supervisory positions and that STARS would provide a supervisor with the ability

to monitor MSAW alerts immediately from every controller position that displays an alert.

The Board explained that it was not the intent of this recommendation to have a controller

workstation be designed for the supervisor but rather to enable the supervisor to be “in the

loop” if an MSAW alert was generated. The Board believed that such an arrangement

would serve as a form of redundancy that could enhance the benefits of the MSAW system

and STARS. 

In its September 25, 1998, letter, the FAA stated that supervisors should be aware

whenever MSAW alerts are generated. Further, the FAA stated that, in STARS, supervisor

awareness of MSAW events is accomplished through aural alarms at each controller

position. According to the FAA, supervisors are expected to be on the control room floor

to monitor all areas of the operation, including MSAW alerts, and are expected to spend a

minimal amount of time at supervisory workstations.

On January 14, 1999, the Safety Board stated that the individual aural alert

speakers located at each controller position should alert a supervisor to the sector

experiencing an MSAW alert. Therefore, supervisors should be able to react to each alert

from their workstation or throughout the operating floor. Because the intent of Safety

Recommendation A-97-27 was satisfied in an alternative manner, it was classified

“Closed—Acceptable Alternate Action.”

1.18.2 Traditional and Enhanced Ground Proximity Warning 

Systems 

1.18.2.1 Traditional Ground Proximity Warning System

Traditional GPWS uses numerous input signals to determine if a terrain collision

threat exists.132 Inputs from the aircraft systems include the radio altitude,133 descent rate

and airspeed, landing gear position, landing flap position, and glideslope information.

This information generates the visual and aural annunciations to the flight crew.

GPWS uses the radio altimeter to calculate closure rate with terrain to predict a

potential collision threat. However, if the terrain rises steeply (for example, a sheer cliff),

the system cannot provide a timely warning to the flight crew. The optional altitude callout

132 For information on the GPWS installed on Korean Air flight 801, see section 1.6.2.2.

133 Radio altitude is derived from the radio altimeter, also called the radar altimeter. The radio altimeter

does not require an accurate barometric pressure setting; rather, it displays the height above the ground by

using time-varying frequency and measuring the differences in the frequency of received waves,

proportional to time and height.
Factual Information 94 Aircraft Accident Report

advisories generated by GPWS are the aircraft’s altitude above the ground as calculated by

the radio altimeter. 

1.18.2.2 Enhanced Ground Proximity Warning System

Enhanced GPWS has the ability to “look ahead” of the aircraft to determine the

terrain elevation along the flightpath. Enhanced GPWS can therefore provide pilots with

visual and aural alerts in advance of an impending impact with terrain, thus allowing pilots

more time than with traditional GPWS to determine the necessary corrective actions to be

taken.134

Enhanced GPWS compares the aircraft’s position, as determined by its on-board

navigational systems (that is, the flight management system [FMS], inertial reference

system, or GPS), with a stored terrain database. Terrain and ground obstructions that may

pose a collision threat along the flightpath of the aircraft result in aural and visual

warnings. The visual warning information is provided to the pilot using the color graphics

capabilities of a dedicated display screen, the color weather radar, or an Electronic Flight

Instrument System map display (depending on the particular installation).

Further, unlike traditional GPWS, enhanced GPWS utilizes an airport position

database to establish a “terrain clearance floor” around all airports. This feature ensures

sufficient terrain clearance regardless of the airplane’s landing gear and flap configuration.

1.18.2.2.1 Notice of Proposed Rulemaking for Enhanced Ground 

Proximity Warning Systems

On August 26, 1998, the FAA issued a notice of proposed rulemaking (NPRM)

addressing the development and installation of a TAWS135 (Docket No. 29312, Notice No.

98-11). The NPRM stated that Technical Standard Order (TSO) C151, titled “Terrain

Awareness and Warning System,” was being developed through the FAA’s TSO process

and that, once the TSO has been completed, the FAA would issue an advisory circular

(AC)136 addressing an acceptable means of obtaining installation approval.

The FAA believed that the installation of a TAWS would ensure that all applicable

airplanes operated under Parts 91, 121, and 135 would have state-of-the-art equipment to

aid in the prevention of CFIT accidents. The FAA’s proposal also applies to operators

conducting flights under Part 125 and operators of U.S.-registered airplanes under Part 129.

The FAA proposed that, for operations conducted under Part 121, the rule would

apply to all turbine-powered airplanes and that, for operations under Parts 91, 125, 129,

134 For information on the aural alerts that would have been generated by enhanced GPWS for flight 801,

see section 1.16.1.

135 In the NPRM, the FAA used the term “TAWS” when referring to enhanced GPWS because the FAA

expected that a variety of systems could be developed to meet the improved standards proposed in the

NPRM.

136 An AC provides nonregulatory guidance to certificate holders for compliance with the FARs.
Factual Information 95 Aircraft Accident Report

and 135, the rule would apply to all turbine-powered airplanes type certificated to have six

or more passenger seats, excluding any pilot seat. (The FAA stated in the NPRM that the

proposed rule applied only to turbine-powered airplanes, but the FAA indicated that it

would consider comments on whether the installation of a TAWS on reciprocating enginepowered airplanes should be required. The FAA also stated that it would study data and

information submitted by respondents before making a determination whether TAWS

should be required for reciprocating engine-powered airplanes.)

The FAA proposed that, beginning 1 year after the effective date of the final rule,

U.S.-registered turbine-powered airplanes manufactured after that date be equipped with

TAWS and that existing turbine-powered airplanes be equipped with TAWS within 4 years

after the effective date of the final rule. The FAA also proposed to amend 14 CFR Sections

121.360 and 135.153 to add an expiration date of 4 years after the effective date of the

final rule for the use of current GPWS systems; thereafter, compliance with those sections

would not be allowed instead of the provisions proposed within the NPRM. In addition,

the FAA’s proposal would also require operators to include in their airplane flight manuals

the appropriate procedures for operating and responding to the audio and visual warnings

of the TAWS. 

In a December 24, 1998, letter to the FAA, the Safety Board indicated that the

NPRM, if promulgated, would have a positive effect on aviation safety by reducing the

possibility for CFIT accidents. However, on May 12, 1999, the Safety Board concluded

that the 4-year installation time frame proposed by the FAA should be shortened to 3 years

for airplanes that currently lack any GPWS protection (see section 1.18.2.4).

The FAA indicated that it expected to issue the final rule by March 2000, with an

effective date 1 year after the date of issuance. According to the FAA, the final rule would

mandate the installation and use of TAWS within 1 year after the effective date on

new-production airplanes and within 4 years after the effective date for existing airplanes. 

1.18.2.3 Department of Transportation Studies on Traditional and 

Enhanced Ground Proximity Warning Systems

In 1995, the FAA commissioned the DOT’s Volpe National Transportation

Systems Center to examine the effectiveness of GPWS and enhanced GPWS in preventing

CFIT accidents in 14 CFR Part 91 operations. The center studied 44 CFIT accidents that

occurred between 1985 and 1994 and involved airplanes operating under 14 CFR Part 91

with 6 to 10 passenger seats. Of the 44 airplanes, 11 were turbojets and 33 were

turboprops, and none of the airplanes had GPWS installed.137 The center used computer

modeling techniques to conclude that (1) GPWS could have prevented 33 of the

44 accidents (75 percent) and 96 fatalities and (2) enhanced GPWS could have prevented

42 of the 44 accidents (95 percent) and 126 fatalities.138

137 These airplanes were not required by the FARs to be equipped with a GPWS.

138 Investigation of Controlled Flight Into Terrain, Aircraft Accidents Involving Turbine-Powered

Aircraft with Six or More Passenger Seats Flying Under FAR Part 91 Flight Rules and the Potential for

Their Prevention by Ground Proximity Warning Systems, DOT-TSC-FA6D1-96-01, 1996.
Factual Information 96 Aircraft Accident Report

Later in 1996, the FAA commissioned the DOT’s Volpe National Transportation

Systems Center for a second study that examined the effectiveness of GPWS and

enhanced GPWS in preventing CFIT accidents involving airplanes operating under

14 CFR Part 121 and 135 or their foreign equivalents. The center studied 47 domestic and

104 foreign CFIT accidents that occurred between 1985 and 1995; 38 of the domestic

accidents and 96 of the foreign accidents involved fatalities. The center developed a

methodology and scheme for selecting a representative sample, and nine accidents were

selected for detailed study and analysis.

The Volpe center found that four of the nine accidents (44 percent) should have

been prevented by the basic GPWS equipment that had been installed. In two of these four

accidents, the GPWS equipment either was disconnected or malfunctioned; in the other

two accidents, poor flight crew coordination after the GPWS warning led to inaction

rather than decisive recovery maneuvers. 

The Volpe center further found that, for all nine accidents, enhanced GPWS would

have provided more warning time than GPWS (which was assumed to be 12 to

15 seconds). For seven of the accidents, warning times with enhanced GPWS would have

exceeded those of GPWS by more than 20 seconds; two of the accidents would have

involved differences of more than 1 minute. The center concluded that “in general,

[enhanced GPWS] should have provided an additional margin in which flight crews could

assess their situation, discover errors, regain situational awareness, and take appropriate

action before impact.” The center noted only one accident for which an assumed enhanced

GPWS warning duration would have been only slightly above the 12- to 15-second GPWS

warning. The center argued that this case, which involved a pilot’s fatal wrong turn toward

mountains, might have been prevented by the visual forward-looking terrain display

installed in enhanced GPWS. Thus, the center believed that it was reasonable to assume

that enhanced GPWS could have prevented all nine (100 percent) of these accidents.

The Part 121 and 135 study credited GPWS as a significant factor in reducing the

frequency of CFIT accidents since 1975. However, the center concluded that “there is

compelling evidence of the potential effectiveness of [enhanced GPWS] in preventing

CFIT accidents.” The study emphasized that CFIT accident prevention would result not

only from the increased warning time after the enhanced GPWS detected terrain threats

but also from the system’s continuous terrain display, which would enable flight crews to

perceive terrain threats and respond to them well before enhanced GPWS would generate

its warnings.139

1.18.2.4 Previous Safety Board Recommendations on Traditional and 

Enhanced Ground Proximity Warning Systems

In 1971, the Safety Board began issuing numerous recommendations to the FAA

regarding the installation and upgrade modification of GPWS. (The FAA first mandated

139 Investigation of Controlled Flight Into Terrain, Selected Aircraft Accidents Involving Aircraft Flying

Under FAR Parts 121 and 135 Flight Rules and the Potential for Their Prevention by Enhanced Ground

Proximity Warning System (EGPWS), DOT-TSC-FA6D1-96-03, 1996.
Factual Information 97 Aircraft Accident Report

the installation of GPWS in 1974 for all 14 CFR Part 121 carriers.) More recently, the

Safety Board has issued recommendations addressing the additional benefits of installing

enhanced GPWS. 

GPWS Development (A-71-53, A-72-19, and A-72-35)

On February 17, 1971, a Southern Airways Douglas DC-9-15, N92S, struck an

electric transmission line static cable during a VOR approach to runway 31 at the

Municipal Airport in Gulfport, Mississippi.140 A successful missed approach was

accomplished, and the aircraft landed safely. On the basis of the results of its investigation,

the Safety Board issued Safety Recommendation A-71-53, asking the FAA to

Develop a ground proximity warning system for use in the approach and landing

phases of operation, which will warn flight crews of excessive rates of descent,

unwanted/inadvertent descent below minimum descent altitudes, or descent

through decision heights. It would be desirable if the equipment now installed

could meet this need.

The FAA responded that it believed that “the present instrumentation and

procedures are safe and adequate provided cockpit disciplines are maintained.” The Safety

Board subsequently classified this recommendation “Closed—No Longer Applicable”

because it was superceded by Safety Recommendation A-72-19. That recommendation

was issued as a result of the June 22, 1971, accident involving a Northeast Airlines

McDonnell Douglas DC-9-31, N982NE, which struck the water during a nonprecision

instrument approach to runway 24 at the airport at Martha's Vineyard, Massachusetts.141

The Safety Board issued Safety Recommendation A-72-19, asking that 

The Administrator require all air carrier aircraft to be equipped with a functional

ground proximity warning device, in addition to barometric altimeters.

On November 14, 1972, Southern Airways charter flight 932, a DC-9, N97S,

crashed during a nonprecision instrument landing approach to runway 11 at the Tri-State

Airport, Huntington, West Virginia.142 The airplane impacted trees on a hill approximately

1 mile west of the runway threshold. All 71 passengers and 4 crewmembers were killed,

and the airplane was destroyed. As a result of its investigation, the Safety Board issued

Safety Recommendation A-72-35 to the FAA, asking that 

The Administrator evaluate the need for the installation and use of ground

proximity warning devices on air carrier aircraft. 

140 National Transportation Safety Board. 1971. Southern Airways, Inc., Douglas DC-9-15, N92S,

Gulfport, Mississippi, February 17, 1971. Aircraft Accident Report NTSB/AAR-71/04. Washington, DC.

141 National Transportation Safety Board. 1972. Northeast Airlines, Inc., McDonnell Douglas DC-9-31,

N982NE, Martha’s Vineyard, Massachusetts, June 22, 1971. Aircraft Accident Report NTSB/AAR-72-04.

Washington, DC.

142 National Transportation Safety Board. 1972. Southern Airways, Inc., DC-9, N97S, Tri-State Airport,

Huntington, West Virginia, November 14, 1972. Aircraft Accident Report NTSB/AAR-72-11. Washington,

DC.
Factual Information 98 Aircraft Accident Report

In its November 2, 1973, letter to the FAA, the Safety Board classified Safety

Recommendation A-72-19 “Closed—Acceptable Alternate Action.” Also, the Board

classified Safety Recommendation A-72-35 “Closed—No Longer Applicable” in the same

letter.

GPWS Installation for 14 CFR Part 135 Operations (A-86-109)

On August 25, 1985, Bar Harbor Airlines flight 1808, a Beech B99, N300WP,

crashed during an ILS approach to Auburn-Lewiston Airport, Auburn, Maine. The

airplane struck trees at an elevation of 345 feet msl in a wings-level attitude 4,000 feet

from the end of the runway threshold and 440 feet to the right of the extended runway

centerline. All eight airplane occupants were killed.

On September 23, 1985, Henson Airlines flight 1517, a Beech B99, N339HA,

crashed during an ILS approach to Shenandoah Valley Airport, Weyers Cave, Virginia.

The airplane struck trees at an elevation of 2,400 feet msl in a wings-level attitude about

6 miles east of the airport. All 14 airplane occupants were killed.

On March 13, 1986, Simmons Airlines flight 1746, an Embraer EMB-110P1,

N1356P, crashed during an ILS approach to Phelps Collins Airport, Alpena, Michigan.

The airplane struck trees at an elevation of 725 feet msl in a wings-level attitude about

1 1⁄2 miles from the end of the runway threshold and about 300 feet to the left of the

extended runway centerline. Three of the nine airplane occupants were killed, five

occupants received serious injuries, and one occupant received minor injuries.

The Safety Board's investigation of these accidents revealed that the accidents

occurred while the airplanes were in controlled flight and the flight crews were attempting

to complete precision instrument approaches in IMC.143 None of the flight crews indicated

that they were experiencing airplane or equipment problems, and none of the postaccident

examinations disclosed airplane or equipment problems that would explain the accidents.

As a result of these three accidents, the Safety Board issued Safety Recommendation

A-86-109, which asked the FAA to

Amend 14 CFR Section 135.153 to require after a specified date the installation

and use of ground proximity warning devices in all multiengine, turbine-powered

fixed-wing airplanes, certificated to carry 10 or more passengers.

On January 8, 1987, the FAA stated that it initiated a proposed regulatory project

for the development of an NPRM for a GPWS requirement for 14 CFR Part 135 operators.

According to the FAA, the rationale and requirements for the NPRM were finalized and

would be presented to the Regulatory Review Board in early 1987. On May 15, 1987, the

Safety Board asked for an update on the status of the NPRM. 

143 For more information on the Bar Harbor, Henson, and Simmons Airlines accidents, see Briefs of

Accident DCA85AA035, DCA85AA037, and DCA86AA021, respectively.
Factual Information 99 Aircraft Accident Report

On May 16, 1989, the FAA stated that the March 1989 Volpe National

Transportation System Center report, titled Investigation of Controlled Flight Into Terrain

(DOT-TSC-FA994-89-10), presented an investigation of CFIT accidents involving

multiengine, fixed-wing, turbine-powered aircraft operating in accordance with 14 CFR

Part 135 at the time of the accident and the potential application for a GPWS. The FAA

stated that, as a result of the Volpe report and the availability of a GPWS at a more

reasonable cost to commuter aircraft, the FAA was considering the issuance of an NPRM

to address the intent of Safety Recommendation A-86-109. On June 20, 1989, the Safety

Board stated that it was pleased that the FAA was considering the issuance of an NPRM. 

On April 24, 1992, the FAA stated that, on March 17, 1992, it issued a final rule

(Docket No. 26202; Amendment No. 135-42) to require that all turbine-powered (rather

than only turbojet) airplanes with 10 or more seats be equipped with an approved GPWS.

On June 10, 1992, the Safety Board stated that it was pleased to note that the FAA had

issued the final rule and that, as a result, Safety Recommendation A-86-109 was classified

“Closed—Acceptable Action.”

GPWS Installation for 14 CFR Part 91 Operations (A-92-55 and A-95-35)

On December 11, 1991, a Bruno’s, Inc., Beechjet 400, N25BR, operating under

14 CFR Part 91, impacted mountainous terrain approximately 3 minutes after takeoff from

Richard B. Russell Airport near Rome, Georgia. The two flight crewmembers and all

seven passengers were killed. The airplane was not equipped with a GPWS and was not

required by the FARs to be so equipped. The Safety Board concluded that, if a GPWS had

been installed on the airplane, a warning would have sounded about 12 seconds before

impact and would have most likely provided sufficient time for the pilots to take action to

avoid flying into terrain.144 As a result of the accident, the Board issued Safety

Recommendation A-92-55, which asked the FAA to

Require all turbojet-powered airplanes that have six or more passenger seats to be

equipped with a ground proximity warning system.

The FAA, however, did not agree with this recommendation. In an October 13,

1992, letter to the Safety Board, the FAA stated that, in making the determination not to

require a GPWS on all turbojet-powered airplanes with six or more passenger seats, it

considered, “among other factors, the operating environment most prevalent for turbojetpowered airplanes, the extent of radar service in the air traffic control system, and the

employment of the minimum safe altitude warning system.” On January 6, 1993, the

Board classified Safety Recommendation A-92-55 “Closed—Unacceptable Action.”

After the June 18, 1994, TAESA Learjet accident at Dulles International Airport,145

the Safety Board issued Safety Recommendation A-95-35, which asked the FAA to

144 National Transportation Safety Board. 1992. Bruno’s, Inc., Beechjet 400, N25BR, Rome, Georgia,

December 11, 1991. Aircraft Accident Report NTSB/AAR/92-01/SUM. Washington, DC.

145 See Safety Recommendation A-94-187 in section 1.18.1.2 for additional information about this

accident.
Factual Information 100 Aircraft Accident Report

Require within 2 years that all turbojet-powered airplanes with six or more

passenger seats have an operating ground proximity warning system installed.

On June 14, 1995, the FAA stated that it had asked the Volpe National

Transportation Systems Center to study CFIT accidents involving turbojet-powered

airplanes equipped with six or more passenger seats and document those CFIT accidents

that would have been avoided if GPWS or enhanced GPWS had been installed.146 The

FAA stated that it would review the results of the study to determine any regulatory action

that would need to be initiated. On August 29, 1995, the Safety Board stated that it would

wait for the study to be completed and then evaluate the actions taken by the FAA in

response to the study’s findings. 

On April 17, 1997, the FAA stated that it had initiated rulemaking proposing to

mandate the installation of enhanced GPWS on all turbine-powered airplanes with six or

more passenger seats.147 The FAA also indicated that the White House Commission on

Aviation Safety and Security issued a recommendation that urged the installation of

enhanced GPWS on commercial aircraft. The FAA stated that it was proposing to revise

14 CFR Parts 91, 121, and 135 to address the Board’s and White House’s

recommendations.

On July 31, 1997, the Safety Board said that it reviewed the results of the study by

the Volpe National Transportation Systems Center. The Board stated that it was pleased

that the FAA had initiated rulemaking activity to revise 14 CFR Parts 91, 121, and 135 to

mandate enhanced GPWS on all turbine-powered airplanes with six or more passenger

seats. The Board indicated that nearly 1 year had passed since the study was completed, and

the Board hoped that the FAA’s important rulemaking action would not be further delayed. 

On January 13, 1998, the Houston Gates Learjet accident occurred. This accident,

which was briefly discussed in section 1.18.1.2, involved a positioning flight operating

under 14 CFR Part 91. The airplane departed from Hobby Airport in Houston for George

Bush Intercontinental Airport, where five people were waiting to board the airplane for a

14 CFR Part 135 charter flight to Fargo, North Dakota. The captain and first officer—the

sole occupants aboard the flight—were killed when the airplane struck trees and impacted

the ground, and the airplane was destroyed by impact forces and fire. The airplane was not

equipped with a GPWS and was not required by the FARs to be so equipped. Although the

Safety Board determined that the probable cause of this accident was flight crew error, the

Board also found that the lack of an FAA requirement for a GPWS on the airplane was a

factor in the accident.

On May 12, 1999, the Safety Board stated that the circumstances of the Houston

Learjet accident, the TAESA Learjet accident, and the Bruno’s Beechjet accident clearly

146 See section 1.18.2.3 for more information about this study.

147 Between the time of the Safety Board’s August 1995 letter and the FAA’s April 1997 letter, the Volpe

study was issued, and an American Airlines CFIT accident involving traditional GPWS occurred. (This

accident is discussed in the Safety Recommendation A-96-101, which is the next recommendation

presented.) 
Factual Information 101 Aircraft Accident Report

indicated the potential to reduce CFIT accidents by requiring the installation of a GPWS

in turbojet-powered airplanes equipped with six or more passenger seats. The Board

further stated that the 1996 DOT study provided compelling evidence that Safety

Recommendation A-95-35 should be broadened to include turboprop-powered airplanes

and require the installation of enhanced GPWS. As a result, the Safety Board classified

Safety Recommendation A-95-35 “Closed—Acceptable Action/Superseded.”148

Enhanced GPWS for Transport-Category Airplanes (A-96-101)

On December 20, 1995, American Airlines flight 965, a Boeing 757, N651AA,

was on a regularly scheduled 14 CFR Part 121 flight from Miami, Florida, to Cali,

Colombia, when it struck trees and crashed into the side of a mountain in night VMC.149

Of the 8 crewmembers and 156 passengers aboard the airplane, all but 4 were killed. The

airplane was equipped with a GPWS, as required. Approximately 12 seconds before

impact, the GPWS began issuing aural warnings of “TERRAIN” and “PULL UP.”

However, the GPWS did not provide the warning in time for the flight crew to

successfully avoid crashing into the mountainous terrain. As a result of this accident, the

Safety Board issued Safety Recommendation A-96-101, asking the FAA to

Examine the effectiveness of the enhanced ground proximity warning equipment

and, if found effective, require all transport-category aircraft to be equipped with

enhanced ground proximity warning equipment that provides pilots with an early

warning of terrain. 

On December 31, 1996, the FAA stated that it had begun evaluating the

effectiveness of enhanced GPWS. Further, the FAA stated its belief that enhanced GPWS

would perform as intended and should significantly increase a pilot’s situational

awareness. The FAA indicated that evaluations to date revealed that enhanced GPWS

would be a valuable aid in preventing CFIT accidents. The FAA anticipated completing its

evaluation by March 1997 and stated that it would initiate appropriate action based on the

results of the evaluation.

On April 11, 1997, the Safety Board acknowledged that the FAA was considering

the issuance of an NPRM to require enhanced GPWS equipment on all civil, turbinepowered aircraft with six or more passenger seats. The Board indicated that it would wait

to review the FAA’s final action.

On May 4, 1999, the FAA stated that, in August 1998, it issued an NPRM

proposing to require the installation and use of TAWS on any U.S.-registered turbinepowered airplane with six or more passenger seats operating under 14 CFR Parts 91, 121,

and 135. According to the FAA, because operators under 14 CFR Part 125 and operators

148 Safety Recommendation A-95-35 was superceded by A-99-36.

149 The investigation of this accident was conducted by the Aeronautica Civil of the Government of

Colombia, with assistance from the Safety Board. For more information, see the Aeronautica Civil of the

Government of Colombia Aircraft Accident Report, Controlled Flight Into Terrain, American Airlines

Flight 965, Boeing 757-223, N651AA, Near Cali, Colombia, December 20, 1995. 
Factual Information 102 Aircraft Accident Report

of U.S.-registered airplanes under 14 CFR Part 129 must comply with 14 CFR Part 91,

they would also have to meet the proposed requirements of the NPRM. The FAA further

indicated that it had issued TSO C151, “Terrain Awareness and Warning System,” for

public comment. According to the FAA, TSO C151 would prescribe the minimum

operational performance standards that a TAWS must meet.150 The FAA stated that the

comment period for TSO C151 was from November 4, 1998, to January 26, 1999. The

FAA also stated that it had extended the ending date of the comment period for the NPRM

from November 24, 1998, to January 26, 1999, to coincide with the ending date of the

comment period for the TSO.

On July 13, 1999, the Safety Board stated that, pending the issuance of the final

rule on the installation and use of TAWS and TSO C151, Safety Recommendation

A-96-101 was classified “Open—Acceptable Response.” In an October 1, 1999, response,

the FAA stated that it had issued the final TSO on August 16, 1999. The FAA also stated

that it expected to issue the final rule by March 2000 with an effective date of 1 year after

the date of issuance.

The Safety Board’s evaluation and classification of Safety Recommendation

A-96-101 are discussed in section 2.8.2.

Enhanced GPWS for Turbine-Powered Airplanes (A-99-36)

As part of its investigation into the 1998 Houston Learjet accident (see the

discussion regarding Safety Recommendation A-95-35), the Safety Board concluded that

the 4-year TAWS installation time frame should be shortened for airplanes that lack any

GPWS protection. On May 12, 1999, the Safety Board issued Safety Recommendation

A-99-36, which asked the FAA to

Require, within 3 years, that all turbine-powered airplanes with six or more

passenger seats that are not currently required to be equipped with a ground

proximity warning system (GPWS) have an operating enhanced GPWS (or terrain

awareness and warning system).

On July 26, 1999, the FAA stated that, in August 1998, it had issued an NPRM on

the installation and use of TAWS on any U.S.-registered turbine-powered airplane with six

or more passenger seats operating under 14 CFR Parts 91, 121, and 135. The FAA

indicated that the NPRM proposed adding new rules that would prohibit the operation of

certain airplanes unless those airplanes were equipped with a TAWS that met the

minimum operational performance standards prescribed in TSO C151, “Terrain

Awareness and Warning System.”

The FAA also stated that, on May 27, 1999, it published a change to the proposed

TSO to include two classes (A and B) of TAWS equipment. According to the FAA, TSO

C151 Class A equipment would be required for airplanes operated under 14 CFR Part 121

and for airplanes configured with 10 or more passenger seats operating under 14 CFR

150 See the discussion in Safety Recommendation A-99-36 for detailed information on TSO C151.
Factual Information 103 Aircraft Accident Report

Part 135, and TSO C151 Class B equipment would be the minimum requirement for

airplanes operating under 14 CFR Part 91 and for airplanes configured with six to nine

passenger seats operating under 14 CFR Part 135. The FAA indicated that both classes of

equipment would include the TAWS features of comparing airplane position information

with an on-board terrain database and providing appropriate caution and warning alerts, if

necessary. Further, the FAA stated that it revised the proposed TSO to include the

airworthiness requirements for both classes of equipment. 

The FAA indicated that it expected to issue the final TSO by September 1999 and

the final rule by March 2000, with an effective date 1 year after the date of issuance.

According to the FAA, the final rule would mandate the installation of TAWS within

1 year after the effective date on new-production airplanes and within 4 years after the

effective date for existing airplanes. The FAA indicated that these compliance dates,

which were established in the current NPRM, were developed based on product

availability and the anticipated manufacturing approval process. The FAA further

indicated that a change in the compliance dates, as recommended in this safety

recommendation, would require publishing a supplemental NPRM. The FAA believed that

any change to the current rulemaking effort would delay the implementation of TAWS

well beyond the proposed dates of the current final rule, as well as the compliance dates

included in the recommendation. On October 1, 1999, the FAA stated that it had issued the

TSO C151 on August 16, 1999. 

The Safety Board’s evaluation and classification of Safety Recommendation

A-99-36 are discussed in section 2.8.2.

1.18.3 Controlled Flight Into Terrain Accident Information

1.18.3.1 Flight Safety Foundation Study of Controlled Flight Into 

Terrain Accidents

In the early 1990s, the Flight Safety Foundation (FSF) created a CFIT Awareness

Task Force to promote general CFIT awareness. This task force evolved into an

international Approach and Landing Accident Reduction Task Force, working under the

auspices of the FSF. According to statistics compiled by the task force, CFIT accidents

have killed more than 9,000 passengers and crewmembers since the beginning of

commercial jet operations in the late 1950s. The statistics also indicate that, between 1988

and 1997, more than 2,800 people were killed in 39 CFIT-related accidents worldwide. 

The FSF task force estimated that about 25 CFIT accidents occur worldwide each

year involving large commercial jet transports and large commuter and regional turboprop

airplanes. Several factors that frequently appeared in CFIT accident reports included night

and limited visibility conditions, terrain not observed until just before impact, loss of

horizontal or vertical situational awareness, unfamiliarity with terrain and obstructions,

flight crew uncertainty about altitudes and distance from the airport, navigational

equipment improperly set or misinterpreted by the flight crew, and an unstabilized

approach.
Factual Information 104 Aircraft Accident Report

The FSF, using statistics from the United Kingdom’s CAA global database, found

that 287, or 46 percent, of the 621 fatal CFIT accidents worldwide between 1980 and 1986

occurred during the approach and landing phase of flight. A study commissioned by the

CAA for the FSF151 examined these 287 fatal approach and landing accidents.152

According to the study, these 287 accidents resulted in 7,185 fatalities to passengers and

crewmembers, which averaged 25 fatalities per accident, or 63 percent of the total aircraft

occupants. 

The study indicated that 75 percent of the accidents occurred when a precision

approach aid was neither available nor used and that nighttime accidents occurred at three

times the rate of those that occurred during daylight conditions. The lack of ground aids

was cited in at least 25 percent of the accidents. The study concluded that the “most

frequent circumstantial factors were non-installation of currently available safety

equipment (generally GPWS systems) and the failure to emphasize the use of crew

resource management.”

The study determined that, in 279 of the accidents,153 the 5 most frequently

identified primary causal factors—omission of action/inappropriate action, lack of

positional awareness in the air, flight handling, “press-on-itis,” and poor professional

judgment/airmanship—accounted for 71 percent of the accidents.154 According to the FSF,

omission of action/inappropriate action generally referred to the crew continuing the

descent below the DH or MDA without visual reference or when visual cues were lost.

Lack of positional awareness in the air generally involved a lack of appreciation of the

aircraft’s proximity to high ground, frequently when the aircraft was not equipped with a

GPWS and when precision approach aids were not available. Press-on-itis referred to a

flight crew’s “determination to get to a destination or persistence in a situation when that

action is unwise.” The study also determined that all five primary causal factors involved

crewmembers.155

The study reported that the number of accidents and the number of fatalities

showed an overall increasing trend and that, if the trend were to continue, “...by 2010

there will be 23 fatal ALAs [approach and landing accidents] with a total of 495 fatalities

annually involving Western-built aircraft (commercial jets, business jets and turboprop

airplanes)....” On the basis of the results of this study, the FSF Approach and Landing

151 “A Study of Fatal Approach-and-landing Accidents Worldwide, 1980-1996,” Flight Safety Digest,

February-March 1998. This study was also included as part of a special FSF report, “Killers in Aviation:

FSF Task Force Presents Facts About Approach-and-landing and Controlled-flight-into-terrain Accidents,”

Flight Safety Digest, November-December 1998 and January-February 1999.

152 The study’s data indicated that, of the 287 approach and landing accidents, 108 occurred on initial

approach, 82 on final approach, and 97 on landing.

153 Of the 287 accidents in the study, 8 were judged to have insufficient information available to

determine a primary causal factor. 

154 Omission of action/inappropriate action was identified in 69 accidents, lack of positional awareness in

52 accidents; flight handling in 34 accidents, “press-on-itis” in 31 accidents, and poor professional

judgment/airmanship in 12 accidents.

155 According to the FSF report, “considering the causal groups, rather than individual factors, “crew”

featured in 228 of the 279 accidents (82 percent)....”
Factual Information 105 Aircraft Accident Report

Accident Reduction Task Force issued nine conclusions and recommended several

initiatives to support each conclusion.156 (The recommendations for each conclusion are

detailed in appendix C.) The conclusions were as follows:

• Establishing and adhering to adequate standard operating procedures and CRM

processes will improve approach and landing safety.

• Improving communication and mutual understanding between ATC services

and flight crews of each other’s operational environment will improve

approach and landing safety.

• Unstabilized and rushed approaches contribute to ALAs.

• Failure to recognize the need for and to execute a missed approach, when

appropriate, is a major cause of ALAs. 

• The risk of ALAs is higher in operations conducted during low light and poor

visibility, on wet or otherwise contaminated runways, and with the presence of

optical physiological illusions. 

• Using the radio altimeter as an effective tool will help prevent ALAs. 

• When the PIC [pilot-in-command] is the PF and the operational environment is

complex, the task profile and workload reduce PF flight management

efficiency and decision-making capability in approach and landing operations. 

• Collection and analysis of in-flight parameters (for example, flight operations

quality assurance programs) can identify performance trends that can be used

to improve the quality of approach and landing operations. 

• Global sharing of aviation information decreases the risk of ALAs. 

1.18.3.2 Factors Involved in Recent Controlled Flight Into Terrain 

Accidents and Incidents

A British Airways Boeing 777 captain who was a member of the FSF’s Approach

and Landing Accident Reduction Task Force and CFIT Awareness Task Force testified at

the Safety Board’s public hearing about the factors that have been involved in CFIT

accidents and incidents. The captain testified that five of six CFIT accidents in 1996 and

1997 occurred during nonprecision approaches. The captain also said that, from 1988 to

1997, one-half of the commercial jet CFIT accidents were during step-down approaches,

even though most of those airplanes had DME available.157

The captain testified that, according to the accident data, the chances of a CFIT

accident occurring during a nonprecision approach is five times greater than during a

156 These conclusions and recommendations were presented at the FSF’s Corporate Aviation Safety

Seminar, held May 5 through 7, 1998.

157 The captain stated that only three CFIT accidents during that time period occurred on precision

approaches and that these accidents experienced a probable failure of the glideslope receiver, a probable

failure of the FD to capture, and a possible situation in which the autopilot was not coupled.
Factual Information 106 Aircraft Accident Report

precision approach. The captain also stated that nonprecision approaches are generally

much more complex than precision approaches because, for many pilots, nonprecision

approaches are less familiar, are more prone to error, and require more comprehensive

briefing. Further, the captain stated that nonprecision approaches need particularly careful

and accurate monitoring and that it is possible, with complex step-down procedures, for

steps to be missed or taken out of order. The captain added, “in other words, to get one

step ahead of the airplane could be fatal.” He recommended eliminating step-down

nonprecision approaches “...because the accident data says we should....” In addition, the

captain testified that nonprecision approaches need much more carefully managed

airplane crew and checklist management because many CFIT accidents occur when the

crew is preoccupied or distracted by other tasks.

The captain stated that 70 percent of the CFIT accidents occurred on final

approach and that most of these aircraft were “...in line with the runway.” The captain

also stated that “...many accident aircraft [were] underneath the three-degree glideslope

[of a precision approach].” Figure 10 shows vertical profile information that was available

from the 40 CFIT accidents and incidents that occurred between 1986 and 1990, as

prepared by Boeing and provided by the FSF’s CFIT Awareness Task Force. 

Figure 10. Vertical profile information from the 40 CFIT accidents and incidents between 

1986 and 1990.

Reproduction courtesy of The Boeing Company and the Flight Safety Foundation’s 

Controlled Flight Into Terrain Awareness Task Force.
Factual Information 107 Aircraft Accident Report

The captain stated his belief that no single measure or piece of aircraft equipment

can prevent CFIT accidents and that a range of measures suited to a particular operator

and operating environment is needed. The captain added that ICAO has planned a series of

CFIT-related actions, including the following:

• the adoption of colored terrain and minimum safe altitude contour presentation

on approach procedure charts to improve their readability and understanding

by a flight crew, particularly in the cockpit environment at night; 

• new requirements and new emphasis on standard operating procedures

(specifically, altitude awareness procedures), including the use of standard or

automated callouts, guidance on the use of autopilot, and the incorporation of

stabilized approach procedures concepts;

• changes to instrument approach procedure design, including the optimum

angle for nonprecision approaches and the application of vertical navigation

(VNAV) or FMS during nonprecision approaches; and

• the translation of the FSF’s Education and Training Aid (see section 1.18.3.3)

from English into the other five languages used by ICAO.158

1.18.3.3 Controlled Flight Into Terrain Training Aids

The Boeing Commercial Airplanes Group, along with the FAA, and the FSF have

developed and published CFIT educational materials and training aids for use by

operators. The purpose of each aid is to heighten flight crew awareness to CFIT precursors

and the methods and techniques to avoid this type of accident.

The Boeing/FAA CFIT Education and Training Aid, which became available to air

carriers in 1997, is presented in five sections. According to the FAA, this training aid,

along with a new videotape, was distributed to all 14 CFR Part 121 and 135 operators for

inclusion in their training programs. Section one provides a broad overview for airline

executives of CFIT problems and possible solutions. Section two, titled “A Decision

Maker’s Guide,” describes airline operations, aviation industry regulators, and industry

efforts to eliminate CFIT. Section three, titled “An Operator’s Guide,” describes causal

factors of CFIT accidents, the traps in which flight crews can find themselves, and specific

in-flight escape maneuvers. Section four describes a model CFIT airline education

program. Section five provides additional background information on CFIT and

references selected reading materials and accident and incident information.

The FSF’s CFIT Task Force developed a CFIT checklist in 1993 to aid in the

avoidance of CFIT accidents. The checklist was designed so that the user, before a flight,

could evaluate the risk factors and identify the potential for a CFIT accident. For example,

the checklist indicated that flying in night IMC significantly increases the risk of a CFIT

accident occurring. The checklist is divided into two diagnostic parts. The first part, titled

“CFIT Risk Assessment,” includes negative destination CFIT risk factors, such as

VOR/DME approaches, airports near mountainous terrain, and radar coverage limited by

158 The captain also indicated that ICAO was considering whether to publish a manual on CFIT avoidance.
Factual Information 108 Aircraft Accident Report

terrain masking. Further, this assessment evaluates risk multipliers, such as IMC weather

and extended crew duty days. The second part, titled “CFIT Risk Reduction Factors,”

includes positive company management traits and the availability of CFIT training

programs.

1.18.3.4 Previous Safety Board Recommendations Related to 

Controlled Flight Into Terrain

Since the early 1970s, the Safety Board has issued numerous safety

recommendations to the FAA in response to CFIT accidents, including those discussed as

part of the GPWS and enhanced GPWS recommendations in section 1.18.2.4 and

approach procedure design recommendations in section 1.18.4.4. This section provides

information on other CFIT-related safety recommendations.

On December 20, 1995, the American Airlines flight 965 accident near Cali,

Colombia, occurred.159 On October 16, 1996, the Safety Board issued Safety

Recommendations A-96-93 through -95, A-96-102, and A-96-106 as a result of the

findings from this accident investigation.160

Safety Recommendation A-96-93 asked the FAA to 

Evaluate the terrain avoidance procedures of air carriers operating transportcategory aircraft to ensure that the procedures provide for the extraction of

maximum escape performance and ensure that those procedures are placed in

procedural sections of the approved operations manuals.

On April 23, 1997, the FAA stated it agreed with the intent of Safety

Recommendation A-96-93 and that it had completed its efforts to evaluate terrain

avoidance procedures. The FAA stated that, in January 1997, it developed and published

the CFIT Education and Training Aid along with Boeing (see section 1.18.3.3). The FAA

also stated that, on February 25, 1997, it issued a revision (Change 2) to AC-120-51B,

“Crew Resource Management,” Appendix 3, “Appropriate CRM Training Topics,”

paragraph 2(1), to recommend that CRM training in LOFT or Special Purpose Operational

Training for flight crewmembers contain a CFIT scenario. According to the FAA, this

paragraph recommends that the training should emphasize prevention through effective

159 See section 1.18.2.4 for more information about this accident.

160 The Aeronautica Civil of the Government of Colombia issued the following CFIT-related

recommendations to the FAA: (1) require that all approach and navigation charts used in aviation

graphically portray the presence of terrain located near airports or flightpaths, (2) encourage manufacturers

to develop and validate methods to present accurate terrain information on flight displays as part of a system

of early ground proximity warning, (3) develop a mandatory CFIT training program that includes realistic

simulator exercises that are comparable to the successful windshear and rejected takeoff training programs,

and (4) evaluate the CFIT escape procedures of air carriers operating transport-category aircraft to ensure

that the procedures provide for the extraction of maximum escape performance and ensure that those

procedures are placed in operating sections of the approved operations manuals. In addition, the Aeronautica

Civil recommended that ICAO evaluate and consider adopting the recommendations of the FSF’s CFIT task

force (see appendix C).
Factual Information 109 Aircraft Accident Report

communication and decision behavior and the importance of immediate, decisive, and

correct response to a ground proximity warning.

On November 13, 1997, the Safety Board acknowledged the progress made by the

FAA but noted that the FAA’s response did not address whether the escape/terrain

avoidance procedures would be included in the procedural sections of approved

operations manuals. Pending further information from the FAA, Safety Recommendation

A-96-93 was classified “Open—Acceptable Response.” 

On August 11, 1999, the FAA stated that it would issue a flight standards

information bulletin that directed POIs to ensure that the aircraft-specific procedure for

maximum escape performance (as depicted in the CFIT training aid), or an equivalent of

that procedure, was contained in each appropriate FAA-approved operations manual. The

FAA indicated that it planned to issue the bulletin by the end of August 1999.

On October 20, 1999, the FAA indicated that it had issued Flight Standards

Information Bulletin for Air Transportation 99-08, “Controlled Flight Into Terrain (CFIT)

Training,” on October 5, 1999. According to the FAA, the bulletin announces the

publication of the CFIT Education and Training Aid and informs POIs that the training aid

is posted on the FAA’s Web site. The FAA stated that the bulletin also directs POIs to

ensure that the aircraft-specific procedure for maximum escape performance is contained

in each appropriate FAA-approved operations manual.

Safety Recommendation A-96-94 asked the FAA to 

Require that all transport-category aircraft present pilots with angle-of-attack

information in a visual format and that all air carriers train their pilots to use this

information to obtain maximum possible airplane climb performance.161

On December 31, 1996, the FAA stated that it had begun an evaluation to assess

the operational requirements for an angle-of-attack162 indicator. The FAA indicated that

the evaluation should be completed by March 1997. 

On April 11, 1997, the Safety Board stated its understanding that the FAA’s

assessment would include implementation and training requirements, the complexity and

cost of the system, and other functions and would indicate the angle-of-attack for

maximum rate climb. The Safety Board also stated its understanding that, if angle-ofattack indicators were warranted, the FAA would take appropriate regulatory action.

Pending an evaluation of the FAA’s completed action, Safety Recommendation A-96-94

was classified “Open—Acceptable Response.”

161 The Safety Board reiterated Safety Recommendation A-96-94 on July 15, 1997. See National

Transportation Safety Board. 1997. Uncontrolled Flight Into Terrain, ABX (Airborne Express), Douglas

DC-8-63, N827AX, Narrows, Virginia, December 22, 1996. Aircraft Accident Report NTSB/AAR-97/05.

Washington, DC.

162 Angle-of-attack is the angle of the airplane wing to the relative wind.
Factual Information 110 Aircraft Accident Report

On May 4, 1999, the FAA stated that it had evaluated the requirements for the

display of angle-of-attack information to obtain the maximum airplane climb

performance. The FAA indicated that angle-of-attack information during an escape

maneuver could provide some improvement in climb performance but that the prevention

of terrain escape maneuvers would provide a much greater safety benefit than the climb

performance improvements gained by the display of angle-of-attack information. 

The FAA indicated that it had reviewed CFIT accidents and analyses of CFIT

accident data prepared by various organizations. The FAA stated that its review found that

accidents have only rarely been caused by the failure to obtain the maximum possible

airplane climb performance during the ground proximity escape maneuver. Thus, the FAA

believed that more effective prevention of CFIT accidents would yield the greatest safety

benefit.

The FAA cited initiatives to prevent CFIT accidents, including TAWS and the use

of FMS with VNAV capability for constant angle of descent approaches. The FAA

believed that these initiatives would greatly improve pilots’ situational awareness with

regard to terrain and would directly reduce the likelihood that pilots using these systems

would need to perform a ground proximity escape maneuver. Further, the FAA believed

that the safety gains from improvements in escape maneuver climb performance, gained

by the introduction of angle-of-attack information, would be overshadowed by the safety

gains from the implementation of TAWS, especially when that system is combined with

other technologies, such as FMS with VNAV capability and GPS.

Regarding the training portion of Safety Recommendation A-96-94, the FAA

stated that it was revising air carrier pilot training requirements contained in 14 CFR Part

121 to include mandatory training in the ground proximity escape maneuver

recommended by manufacturers for their specific airplane(s). The FAA indicated that one

objective of this training would be to improve pilot actions in achieving maximum

airplane climb performance during the escape maneuver. In addition, the FAA stated that

the regulatory proposal would refer to the guidance in the CFIT Education and Training

Aid, which provides instructions on how to achieve the optimum angle-of-attack (given

the indications available in the airplane) and the manufacturers’ recommended ground

proximity escape maneuvers.

Safety Recommendation A-96-95 asked the FAA to 

Develop a controlled flight into terrain training program that includes realistic

simulator exercises comparable to the successful windshear and rejected takeoff

training programs and make training in such a program mandatory for all pilots

operating under 14 CFR Part 121. 

On April 23, 1997, the FAA stated it agreed with the intent of Safety

Recommendation A-96-95 and that it had completed its efforts to evaluate terrain

avoidance procedures. The FAA stated that, in January 1997, it developed and published

the CFIT Education and Training Aid along with Boeing. The FAA also stated that, on

February 25, 1997, it issued Change 2 to AC-120-51B Appendix 3, paragraph 2(1), to
Factual Information 111 Aircraft Accident Report

recommend that CRM training in LOFT or Special Purpose Operational Training for flight

crewmembers contain a CFIT scenario. According to the FAA, this paragraph

recommends that the training should emphasize prevention through effective

communication and decision behavior and the importance of immediate, decisive, and

correct response to a ground proximity warning.

On November 13, 1997, the Safety Board acknowledged the progress made by the

FAA but noted that the FAA’s response did not indicate that the newly developed CFIT

training program was mandatory, as urged by the recommendation. Pending further

information from the FAA, Safety Recommendation A-96-95 was classified “Open—

Acceptable Response.”

On August 11, 1999, the FAA stated that it had initiated an NPRM proposing to

mandate training in CFIT, including flight training in simulators and the ground proximity

escape maneuver. The FAA indicated that the NPRM was expected to be published in

December 2000. 

The Safety Board’s evaluation and classification of Safety Recommendation

A-96-95 are discussed in section 2.8. 

Safety Recommendation A-96-102 asked the FAA to 

Require that all approach and navigation charts graphically present terrain

information.163

On December 31, 1996, the FAA stated that it agreed with the intent of this

recommendation. However, the FAA stated that it was not necessary to depict terrain on

IFR en route low-altitude charts because the off-route obstruction clearance altitudes

adequately presented terrain and obstruction clearance information. In addition, the FAA

indicated that the Government/Industry Charting Forum, chaired by the FAA’s Air Traffic

Service, was evaluating the possibility of adding terrain information (contour lines and

shading) graphically on approach charts. 

On April 11, 1997, the Safety Board stated that, although the FAA’s action

regarding approach charts was appropriate, the Board did not agree with the FAA that

current off-route obstruction clearance altitudes adequately presented terrain and

obstruction clearance information. The Board reiterated that the intent of this

recommendation was to have terrain information graphically presented on all approach

and navigation charts.

On February 19, 1998, the FAA stated that the Task Group 31 from the Air

Cartographic Committee (a Government interagency and aviation industry committee)

was evaluating the possibility of adding contour lines and shading on the plan view

163 The Safety Board issued this recommendation because Jeppesen Sanderson was changing the

portrayal of terrain on some, rather than all, of its charts. Specifically, Jeppesen was revising approach charts

only if they displayed terrain that was above 2,000 feet within 6 miles of an airport; local area charts were

being revised only if they displayed terrain that was more than 4,000 feet above the plan view of an airport.
Factual Information 112 Aircraft Accident Report

portion of approach charts for terrain-impacted airports only. The FAA also stated its

belief that the addition of contour lines and tinting to IFR en route charts has not been

supported by users and industry personnel and that sufficient information on en route

charts obviates the need for such changes. Further, the FAA stated that overlaying

additional information into charts that already contained a considerable amount of

information could diminish the clarity of existing information on those charts.

On September 3, 1998, the Safety Board stated that the points the FAA raised with

regard to adding information to en route charts were valid. However, the Board noted that

these concerns did not apply to terminal navigation charts and approach charts. The Safety

Board continued to believe that the FAA should do all it can to enhance pilots’ situational

awareness regarding proximity to terrain and that adding readily interpretable terrain

information to navigation charts would be an economical way to accomplish this goal. 

The Safety Board indicated that it would await FAA action regarding approach

charts after the efforts of Task Group 31 were completed. Because the FAA appeared

unwilling to require that terminal charts graphically portray terrain information to help

prevent CFIT accidents, Safety Recommendation A-96-102 was classified “Open—

Unacceptable Response.” 

On July 7, 1999, the FAA stated that it met with the Safety Board on March 12,

1999, to clarify the intent of this safety recommendation and discuss the issue of adding

terrain contours to all charts. At this meeting, the FAA indicated that it would consider

placing terrain contours only on en route area charts. According to the FAA, this plan was

proposed in April 1999 at the Government/Industry Aeronautical Charting Forum, which

endorsed the proposal. The FAA stated that it was developing funding requirements with

the National Oceanic and Atmospheric Administration and that, pending funding

approval, it would submit a requirements document to the Interagency Air Cartographic

Committee to amend the chart specifications to add terrain contours to en route area

charts. The FAA also stated that it was planning to add terrain contours on instrument

approach procedure charts for terrain-impacted airports.

On September 24, 1999, the Safety Board stated that, on the basis of the FAA’s

commitment to consider adding terrain contours to en route area charts only, Safety

Recommendation A-96-102 was classified “Open—Acceptable Alternate Response.” 

Safety Recommendation A-96-106 asked the FAA to 

Revise Advisory Circular 120-51B to include specific guidance on methods to

effectively train pilots to recognize cues that indicate that they have not obtained

situational awareness, and provide effective measures to obtain that awareness.

On December 31, 1996, the FAA stated that it would fund a research project to

determine cues that flight crewmembers could readily recognize to indicate situational

awareness problems. According to the FAA, this project would focus on developing

specific cues for situational awareness in automated cockpits. The FAA indicated that, as

soon as this project was completed, it would revise AC 120-51B to include guidance on
Factual Information 113 Aircraft Accident Report

training flight crews in cue recognition. On April 11, 1997, the Safety Board stated that it

was waiting to evaluate the FAA’s revised version of AC 120-51B.

On August 3, 1998, the FAA stated that the results of its research project were

outlined in a report, titled Guidelines for Situation Awareness Training, which was

published in February 1998. According to the FAA, the report included an overview,

specific training tips, and sample training courses for use by the aviation community. The

FAA indicated that it would incorporate guidance on cue recognition training for flight

crewmembers in AC 120-51B. On November 2, 1998, the Safety Board restated that it

would wait to evaluate the FAA’s revised version of AC 120-51B.

On December 11, 1998, the FAA stated that, on October 30, 1998, it issued AC

120-51C, “Crew Resource Management Training,” a revision to AC 120-51B. The FAA

stated that Appendix 3, “Appropriate CRM Training Topics,” paragraph 2(m), specifically

addressed training for pilots in recognizing cues that indicate lack or loss of situational

awareness in themselves and others and training in countermeasures to restore that

awareness. According to the FAA, paragraph 2(m) reiterates that training should

emphasize the importance of recognizing each pilot’s relative experience level, experience

in specific duty positions, preparation level, planning level, normal communication style

and level, overload state, and fatigue state. Further, the FAA stated that training should

emphasize that improper procedures, adverse weather, and abnormal or malfunctioning

equipment might reduce situation awareness. In addition, the FAA stated that AC 120-51B

references the Guidelines for Situation Awareness Training report because of the AC’s

expanded guidance on cues and countermeasures.

On March 1, 1999, the Safety Board stated that the amendments to AC 120-51B,

which resulted in the issuance of AC 120-51C, met the intent of this recommendation.

Accordingly, Safety Recommendation A-96-106 was classified “Closed—

Acceptable Action.”

1.18.3.5 Previous Controlled Flight Into Terrain Accidents Related to 

Nonprecision Instrument Approach Procedures

As stated in section 1.18.3.2, accident data has shown that the chances of a CFIT

accident occurring during a nonprecision approach is five times greater than during a

precision approach. In addition to the CFIT events discussed previously (including the

USAir flight 105 incident in Kansas City, Missouri, and the American Airlines flight 965

accident in Cali, Colombia) and in section 1.18.4.4 (American Airlines flight 1572 in East

Granby, Connecticut), the Safety Board has investigated the following CFIT accidents that

occurred while the airplane was on a nonprecision approach: 

On February 18, 1989, a Flying Tigers Boeing 747-200, operating as a cargo flight

under 14 CFR Part 121, crashed while on an NDB approach to Subang International

Airport in Kuala Lumpur, Malaysia. Night visual conditions prevailed around the airport

at the time of the accident. All four airplane occupants were killed, and the airplane was

destroyed. The investigation into this accident was being conducted by the Department of

Civil Aviation of the Government of Malaysia with the assistance of the Safety Board.
Factual Information 114 Aircraft Accident Report

On June 2, 1990, about 0937 Alaskan daylight time, Markair, Inc., flight 3087, a

Boeing 737-2X6C, N670MA, operating under 14 CFR Part 121, crashed about 7 1⁄2 miles

short of runway 14 at Unalakleet, Alaska, while executing a localizer-only approach in

IMC. One flight attendant received serious injuries; the captain, the first officer, and a

flight attendant received minor injuries; and the aircraft was destroyed. The Safety Board

determined that the probable cause of the accident was deficiencies in flight crew

coordination, the crew’s failure to adequately prepare for and properly execute the

localizer-only runway 14 nonprecision approach, and the crew’s subsequent premature

descent.164

On April 3, 1996, a U.S. Air Force CT-43A (737-200) carrying the Secretary of

Commerce, other Government officials, and a delegation of business executives crashed

on a mountainside while on an NDB approach to Cilipi Airport in Croatia. All 35 people

aboard the airplane were killed. The Safety Board provided technical assistance to the Air

Force during its investigation.165

1.18.4 Industry Actions to Improve the Safety of Nonprecision 

Instrument Approaches Conducted by Air Carriers

1.18.4.1 Nonprecision Approach Procedures 

According to the Air Line Pilots Association (ALPA),166 limited data indicate that

airline transport crews conduct only about one to three nonprecision approaches per year

and practice these approaches in a simulator “just as infrequently.” Thus, ALPA concluded

that the risk associated with this “inherently less safe type of approach” is compounded by

the infrequency of flight crew exposure and practice. ALPA stated that most nonprecision

approaches are presented in a series of step-down altitudes and that, although step-down

altitudes may be satisfactory for light, slow, maneuverable aircraft, they are unacceptable

for transport-category aircraft. ALPA further stated that these step-down altitudes are in

fact directly contrary to the underlying concept of the stabilized approach because they

require multiple power and pitch changes to be flown as charted. ALPA believed that

approach charts and procedures should be modified to provide the information necessary

to conduct a stabilized descent without explicit vertical guidance.

The issue of nonprecision approaches flown by air carrier (primarily turbojet)

airplanes has been debated, especially in light of the recent CFIT accidents that occurred

during the execution of a nonprecision approach. ALPA stated that “all turbojet air carrier

airports need to have a precision approach available at all times in the appropriate landing

direction.” Further, ALPA believed that it is “problematic at best” for a “500,000 pound

164 National Transportation Safety Board. 1991. Controlled Flight Into Terrain, Markair Flight 3087, Boeing

737-2X6C, N670MA, Unalakleet, Alaska. Aircraft Accident Report NTSB/AAR-91/02. Washington, DC.

165 For more information, see the Air Force’s Accident Investigation Board Report, United States Air

Force CT-43A [Boeing 737], 73-1149, 3 April 1996, at Dubrovnik, Croatia.

166 See Air Line Pilots Association Report on Accident Involving Korean Air Flight 801 at Agana, Guam,

on August 6, 1997, dated June 24, 1998.
Factual Information 115 Aircraft Accident Report

aircraft to transition from level flight (at MDA) and very high thrust settings, to a

stabilized approach and touchdown in 15 to 20 seconds (the distance covered in one mile

visibility at 180 knots)” because of the size of the aircraft and approach speeds at which

the nonprecision approaches are flown.

1.18.4.2 Approach Chart Terrain Depiction

According to testimony at the Safety Board’s public hearing by the Senior

Corporate Vice President of Flight Information Technology and External Affairs for

Jeppesen Sanderson, Inc., approach chart manufacturers use various methods to depict

obstructions and high terrain on published approach charts. Some en route charts and the

plan view of some terminal approach charts use contour lines and color shading to depict

various height gradients with symbols for high obstructions. Other charts use broader

colored areas for terrain depiction and specify a minimum sector altitude for obstacle

clearance in segmented areas around the airport. In some instances, terrain may be

depicted on the plan view of some approach charts but not on other charts published by the

same manufacturer.

Currently, no chart publisher depicts terrain or obstructions on the profile view,

which depicts the inbound course descent profile from the IAF to the landing or MAP.

Further, the FAA Terminal Instrument Procedures (TERPS) manual contains no

requirement for a standardized format that chart manufacturers must adhere to when

depicting terrain on an approach chart, except for the requirement to depict the height of

certain obstructions. 

 The Jeppesen Sanderson official testified that “the Agana ILS 6 Left approach did

not have terrain [depicted on the chart]...because through the agreements that we’ve had

with our airlines, seminars in the airline community, as well as a lot of the general aviation

input, it is believed by Jeppesen that...there should be criteria because you don’t want

terrain to be on all charts; you want it there when it’s significant.” The official added that,

for Jeppesen to depict terrain on a chart, there needs to be at least one elevation that is

4,000 feet or greater above the airport in at least one plan view of the airport or, if there is

one elevation that is 2,000 feet above the airport within 6 miles, then contour lines need to

start at the nearest 1,000 feet to the airport elevation and appear at 1,000-foot intervals all

the way up to the top altitude that is depicted. 

The Jeppesen official’s testimony discussed the difficulties of obtaining accurate

worldwide terrain data through public sources. The official said that inaccurate

information was one of several reasons for not providing terrain information on the charts.

The official further stated that there are many sources for terrain information but that the

information needs to be publicly available so that chart manufacturers can have ready

access.

The Chief Engineer of Flight Safety Systems at AlliedSignal, Inc., testified at the

Safety Board public hearing about the acquisition and accuracy of terrain data. The

official indicated that terrain data needs to be collected to build the database not only for

chart manufacturers but also for companies that are incorporating such data into enhanced
Factual Information 116 Aircraft Accident Report

GPWS or TAWS. The official also testified that some countries still consider terrain data

to be a military secret. 

1.18.4.3 Federal Aviation Administration Form 8260 

FAA Form 8260 provides charting companies with information for publishing

instrument procedures. This form includes data for the terminal area and final and missed

approach standards. The manager of the FAA’s Western Flight Procedures Development

Branch testified at the Safety Board’s public hearing that the FAA distributes approach

procedures to industry user groups (including ALPA, the Air Transport Association, and

the Aircraft Owners and Pilots Association) and airport operators for comment. The

manager testified that the user groups receive information that describes the approach in

words or numbers and does not depict the proposed published approach. According to

ALPA’s submission, the information that the FAA releases “bears no resemblance to the

final user product,” which “seriously hampers the ability to readily and effectively critique

the proposed approach procedure.”

1.18.4.4 Previous Safety Board Recommendations Related to 

Approach Procedure Design

On November 12, 1995, American Airlines flight 1572, a McDonnell Douglas

MD-83, N566AA, collided with trees in East Granby, Connecticut, while on final

approach to runway 15 at Bradley International Airport in Windsor Locks, Connecticut.167

The airplane then landed safely at the airport. Of the 78 airplane occupants, 1 passenger

received minor injuries during the emergency evacuation. The Safety Board determined

that the probable cause of this accident was the flight crew’s failure to maintain the

required MDA until the required visual references identifiable with the runway were in

sight. As a result of its investigation, the Board issued Safety Recommendations

A-96-128, A-96-129, and A-96-131 through -133 on November 13, 1996.

Safety Recommendation A-96-128 asked the FAA to 

Evaluate Terminal Instrument Procedures design criteria for nonprecision

approaches to consider the incorporation of a constant rate or constant angle of

descent to minimum descent altitude in lieu of step-down criteria.

On February 24, 1997, the FAA stated that it would begin implementation of

instrument approach development proposals in late 1997. On June 26, 1997, the Safety

Board stated that it was waiting to review the pending FAA proposals in response to this

recommendation. On January 28, 1998, the FAA stated that it developed draft criteria to

provide a constant angle of descent for aircraft with area and vertical navigation and that

these criteria were incorporated into a draft order, which was being coordinated with

167 National Transportation Safety Board. 1996. Collision With Trees on Final Approach, American

Airlines Flight 1572, McDonnell Douglas MD-83, N566AA, East Granby, Connecticut, November 12, 1995.

Aircraft Accident Report NTSB/AAR-96/05. Washington, DC.
Factual Information 117 Aircraft Accident Report

industry. The FAA anticipated that the final order would be published in June 1998. On

April 15, 1998, the Safety Board stated that it would wait to review the final order.

On August 7, 1998, the FAA stated that, on February 13, 1998, it issued a revision

(Change 17) to Order 8260.3B, “United States Standard Terminal Instrument Procedures

(TERPS),” which requires descent angles and descent gradients to be computed for

nonprecision approaches by the FAA and subsequently depicted on aeronautical charts

supplied by the National Ocean Service. The FAA indicated that the angles and descent

gradients would be integrated during biennial reviews of each instrument approach

procedure. According to the FAA, Change 17 states that the optimum gradient on the final

approach segment is 318 feet per nautical mile, which approximates a 3° descent angle

and allows VNAV-equipped aircraft to perform a stabilized descent on final approach

using a computed VNAV path. Depiction of a descent gradient allows pilots to determine a

target rate of descent to be maintained to fly a stabilized final approach path. Change 17

also addresses the elimination of a step-down fix through manipulation of either the FAF

altitude/location or the step-down fix altitude/location. When use of the step-down fix

cannot be avoided, the descent angles are provided for the portion of the final segment

from the step-down fix to the runway threshold. 

Additionally, the FAA stated that, on May 26, 1998, it issued Order 8260.47,

“Barometric Vertical Navigation (VNAV) Instrument Procedures Development.”

According to the FAA, this order contains criteria for design of stand-alone area

navigation approaches using barometric VNAV guidance on the final approach segment.

Approaches so designed are to specify the vertical path angle from the FAF to the runway

threshold. In addition, the MDA of a conventional nonprecision approach has been

replaced by a decision altitude. The FAA stated that the use of a decision altitude was

authorized because an allowance has been made for height loss during a missed approach

and an obstacle assessment has been conducted of the visual segment (runway threshold to

decision altitude point) and found to be clear of obstructions.

Because the new standards met the intent of Safety Recommendation A-96-128, it

was classified “Closed—Acceptable Action” on December 8, 1998. 

Safety Recommendation A-96-129 asked the FAA to

Examine and make more effective the coordinating efforts of the flight inspection

program and the procedures development program, with emphasis on ensuring

quality control during the development, amendment, and flight inspection process

for instrument approaches.

On February 24, 1997, the FAA said that it had established a test program to

ensure interaction between the flight inspection program and the procedures development

program. On June 11, 1997, the FAA stated that it completed its first test program to

ensure interaction between the flight inspection program and the procedures development

program. According to the FAA, the test program involved the placement of a liaison

position (effective March 16, 1997) in the flight inspection central operations office to

respond to queries and ensure resolution of all issues. The FAA added that the individual
Factual Information 118 Aircraft Accident Report

in this position served as a focal point for the two offices to correct discrepancies found

during flight, enhanced the interaction between the offices, conveyed information to flight

inspection crews, and ensured standardization. 

On September 8, 1997, the Safety Board stated that the actions taken to effectively

coordinate the functions of the procedures development and flight inspection programs

had satisfied the intent of the recommendation. Therefore, Safety Recommendation

A-96-129 was classified “Closed—Acceptable Action.” 

Safety Recommendation A-96-131 asked the FAA to

Include a more comprehensive set of guidelines concerning precipitous terrain

adjustments in the Terminal Instrument Procedures (FAA Order 8260.3B)

Handbook, clarifying the definition of precipitous terrain and establishing defined

criteria for addressing the potential effect of such terrain.

On January 28, 1998, the FAA stated that it was developing a plan to revise the

guidelines concerning precipitous terrain adjustments currently contained in the TERPS

handbook. The FAA noted that it received appropriate funding and negotiated a contract

with the National Center for Atmospheric Research to develop a plan to address this

recommendation. The FAA expected that it would be provided with the findings of the

center’s effort by the end of fiscal year 1998. On April 15, 1998, the Safety Board

indicated that it would await further information from the FAA.

On June 17, 1999, the FAA stated that it was continuing its efforts to revise the

guidelines concerning precipitous terrain adjustments currently contained in the TERPS

Handbook. According to the FAA, the National Center for Atmospheric Research

developed a prototype software package that examines digital terrain elevation data from

the Defense Mapping Agency’s terrain elevation database. This software uses weighted

parameters to determine if the terrain underlying the primary, secondary, and buffer area

approach segments are high, steep, or rough enough to be considered precipitous. The

output of this software specifies the minimum adjustment to the required obstacle

clearance for precipitous terrain in each segment. The FAA indicated that the TERPS

Handbook would be revised to require the use of this software in identifying precipitous

terrain and determining the minimum required adjustment for such terrain. On August 20,

1999, the Safety Board stated that, pending final modification of the TERPS Handbook,

Safety Recommendation A-96-131 was classified “Open—Acceptable Response.”

Safety Recommendation A-96-132 asked the FAA to

Review and evaluate the appropriateness of the let-down altitudes for all

nonprecision approaches that have significant terrain features along the approach

course between the initial approach fix and the runway. Airline safety departments

and pilot labor organizations, such as the Allied Pilots Association and the Air

Line Pilots Association, should be consulted as part of this review.
Factual Information 119 Aircraft Accident Report

On December 30, 1997, the FAA said that it established a mandatory review for

significant terrain features as part of its biennial review process. The FAA stated that

Order 8260.19C, “Flight Procedures and Airspace,” section 8, includes procedures for

reviews of instrument procedures, which are to be conducted every 2 years or more

frequently when deemed necessary. According to the FAA, the reviews are to be

conducted in accordance with Order 8260.3B, “United States Standard Terminal

Instrument Procedures (TERPS),” chapter 3, “Takeoff and Landing Minimums.”

Paragraph 323a, “Precipitous Terrain,” states that “when procedures are designed for use

in areas characterized by precipitous terrain, in or outside of designated mountainous area,

consideration must be given to induced altimeter errors and pilot control problems which

result when winds of 20 knots or more move over such terrain.” The paragraph also states

that, for areas in which these conditions are known to exist, the required obstacle

clearance in the final approach segment should be increased. 

The FAA added that Order 8260.19C stated that user comments should be solicited

to obtain the best available local information to ensure that requirements for obstacle

clearance, navigational guidance, safety, and practicality were met. The FAA also

indicated that, on June 2, 1997, it reemphasized the procedures to be followed when

conducting a periodic review of an instrument procedure. According to the FAA, the

procedures require that obstacles, including terrain, be considered as potential precipitous

terrain when developing or amending a standard instrument approach procedure and that

these obstacles are to be evaluated and appropriate adjustments are to be made according

to existing FAA orders and guidelines. The procedures also require that discussion and

coordination with the users, airline safety departments, and pilot labor organizations are

included in the review process.

On April 7, 1998, the Safety Board noted that the FAA had established a

mandatory review for significant terrain features as part of its biennial review process. The

Board also noted that the FAA had reemphasized that these procedures be followed when

conducting a periodic review of an instrument procedure. Because these actions met the

intent of Safety Recommendation A-96-132, it was classified “Closed—Acceptable

Action.” 

Safety Recommendation A-96-133 asked the FAA to

Solicit and record user comments about difficulties encountered in flying a

particular approach to evaluate approach design accurately.

On February 24, 1997, the FAA stated that it would “invite airspace users to

comment on dangerous approaches.” On June 11, 1997, the FAA said that it had sent

letters to various organizations, including the Allied Pilots Association, ALPA, the Air

Transport Association, and the Aircraft Owners and Pilots Association, to request

comments and concerns from their members regarding instrument flight procedures.

On September 8, 1997, the Safety Board stated that it had received copies of the

letters from the industry organizations that had responded to the FAA’s letter. Because the
Factual Information 120 Aircraft Accident Report

FAA’s effort met the intent of Safety Recommendation A-96-133, it was classified

“Closed—Acceptable Action.” 

1.18.5 Flight Crew Decision-making

1.18.5.1 Safety Board Study of Flight Crew Involvement in Major Accidents

In a 1994 safety study,168 the Safety Board examined the operating environments

and errors made by flight crewmembers in 37 major accidents between 1978 and 1990.

The safety issues examined in the report included the performance of flight crews when

the captain was the PF, the performance of the PNF in monitoring and challenging errors

made by the PF, and the adequacy of CRM training programs.

The study concluded that the captain was the PF in more than 80 percent of the

37 accidents reviewed. This result was significant because U.S. air carrier flights during

the study’s time frame were divided about equally between those flown by the captain and

those flown by the first officer.

The Safety Board identified 302 flight crew errors in the 37 accidents; the median

number of errors per accident was 7. Of the total number of errors, 232 were considered

primary errors, and 70 were considered secondary errors. The primary error categories

identified by the Safety Board included aircraft handling, communication, navigational,

procedural (for example, not conducting or completing required checklists or not following

prescribed checklist procedures), resource management, situational awareness (for example,

controlling the airplane at an incorrect target altitude), systems operation, and tactical

decision (for example, improper decision-making, failing to change a course of action in

response to a signal to do so, or failing to heed warnings or alerts that suggest a change in

the course of actions). Secondary errors resulted from the failure of a crewmember to

monitor or challenge a primary error made by the other crewmember. Table 4 shows the

distribution of the 302 errors identified in the 37 accidents by type of error.

The Safety Board’s study determined that procedural, tactical decision, and

resource management errors were largely errors of omission and that navigational and

most of the aircraft handling, communication, and systems operation errors were errors of

commission. Of the 232 primary errors identified, 123 (53 percent) were errors of

omission, and 109 (47 percent) were errors of commission.

The safety study also determined that captains were responsible for 168 of the 302

identified errors. Of the 168 errors made by captains, 49 (29 percent) were tactical

decision errors, the most common error type attributed to captains. The 49 tactical

decision errors made by captains accounted for 96 percent of the 51 tactical decision

errors made by all crewmembers, which is consistent with the captain’s ultimate

responsibility for decisions. The study also found that procedural (23 percent) and aircraft

168 See National Transportation Safety Board. 1994. A Review of Flightcrew-Involved Major Accidents of

U.S. Air Carriers, 1978 Through 1990. Safety Study NTSB/SS-94/01. Washington, DC.
Factual Information 121 Aircraft Accident Report

handling (20 percent) were the next most common error types made by captains. The

aircraft handling errors made by captains accounted for 33 (72 percent) of the 46 aircraft

handling errors made by all crewmembers, which is consistent with the captain conducting

the PF duties on more than 80 percent of the accident flights reviewed in the study.

Further, the study stated that a common pattern in 17 of the 37 accidents was a

tactical decision error by the captain (more than one-half of which constituted a failure to

initiate a required action) followed by the first officer’s failure to challenge the captain’s

decision. The study also concluded that, of the 49 tactical decision errors made by

captains, 44 (90 percent) were made while the captain was serving as the PF and that 26

(59 percent) of these errors were errors of omission. Thus, the most common tactical

decision error was the failure of a captain serving as the PF to take action when the

situation demanded change. In addition, of the 26 tactical decision errors made by captains

that were errors of omission, 16 (62 percent) involved the captain’s failure to execute a goaround during the approach. These 16 errors were made during 10 different accident

sequences. Of the 16 failures to execute a go-around, 8 involved an unstabilized approach.

The study found that the 70 monitoring/challenging errors committed by flight

crewmembers occurred in 31 (84 percent) of the 37 accidents reviewed in the study and

that most of these errors played very important roles in the accidents. The study concluded

Table 4. Distribution of errors identified in the 37 accidents reviewed in the Safety 

Board’s 1994 safety study.

Type of error Number Percent Number of accidents

Primary error

 Aircraft handling 46 15.2 26

 Communication 13 4.3 5

 Navigational 6 2.0 3

 Procedural 73 24.2 29

 Resource management 11 3.6 9

 Situational awareness 19 6.3 12

 Systems operation 13 4.3 10

 Tactical decision 51 16.9 25

Secondary error

 Monitoring/challenging 70 23.2 31
Factual Information 122 Aircraft Accident Report

that the highest percentage of the unmonitored/unchallenged errors were tactical decision

errors (40 percent). 

In addition, the study found that, of the 15 accidents for which information was

available, 11 (73 percent) occurred during the first duty day together for the captain and

first officer. Of the 16 accidents for which data were available, 7 (44 percent) occurred

during the crewmembers’ first flight together. According to the study, these rates are

substantially higher than the percentage of crews who would be expected to be paired for

the first time on any given flight or day.

Finally, the study examined the effect of the length of time since awakening (TSA)

on the errors committed by flight crewmembers in the accident sequence. The

performances of flight crews in which both the captain and the first officer had been

awake a long time (average TSA length, 13.6 hours) were compared with flight crews in

which both the captain and the first officer had been awake a short time (average TSA

length, 5.3 hours). The Safety Board found that both the number and type of errors made

by the flight crews varied significantly according to the TSA length. Specifically, high

TSA crews made an average of 40 percent more errors (almost all of which were errors of

omission) than low TSA crews. 

High TSA crews made significantly more procedural errors and tactical decision

errors than low TSA crews. These results suggested that the degraded performance by

high TSA crews tended to involve ineffective decision-making (such as failing to perform

a missed approach) and procedural slips (such as not making altitude awareness callouts)

rather than a deterioration of aircraft handling skill. Also, the number and types of errors

made by the flight crews varied according to the TSA length before the accident. The

median TSA periods were quite high: 12 hours for captains and 11 hours for first officers.

Those pilots who had been awake longer than the median TSA length for their crew

position made more decision-making errors and procedural errors than pilots who had

been awake for less time.169

1.18.5.2 Previous Safety Recommendations on Flight Crew 

Decision-making 

On the basis of the findings of its safety study, the Safety Board issued Safety

Recommendations A-94-3 and A-94-4 on February 3, 1994. Safety Recommendation

A-94-3 asked the FAA to 

Require U.S. air carriers operating under 14 CFR Part 121 to provide, for flight

crews not covered by the Advanced Qualification Program, line operational

simulation training during each initial or upgrade qualification into the flight

engineer, first officer, and captain position that (1) allows flight crews to practice,

under realistic conditions, nonflying pilot functions, including monitoring and

challenging errors made by other crewmembers; (2) attunes flight crews to the

169 For a discussion of previous accidents in which the Safety Board determined that fatigue was a factor,

see section 1.18.6.
Factual Information 123 Aircraft Accident Report

hazards of tactical decision errors that are errors of omission, especially when

those errors are not challenged; and (3) includes practice in monitoring and

challenging errors during taxi operations, specifically with respect to minimizing

procedural errors involving inadequately performed checklists.

On April 26, 1994, the FAA stated that it was amending AC 120-51A, “Crew

Resource Management,” to emphasize the areas detailed in the recommendation. On

July 6, 1994, the Safety Board noted that including the recommendation’s material in an

AC would be an acceptable alternative to regulatory change. However, on May 8, 1995,

the Safety Board expressed disappointment that the revised AC 120-51B (issued on

January 3, 1995) made no specific reference to practicing PNF procedures, such as

monitoring and challenging the errors of the other pilots, during line-oriented simulation

training. Likewise, the AC contained no specific references to line-oriented simulation

training in the areas of monitoring and challenging tactical decision errors or inadequately

performed taxi checklist procedures. 

On September 8, 1995, the FAA issued a revision (Change 2) to AC 120-51B. On

January 16, 1996, the Safety Board stated that the revised AC’s reference to line

operational simulation was responsive to all aspects of Safety Recommendation A-94-3.

The provisions for PNF functions, monitoring and challenging of errors made by other

crewmembers, tactical decision errors that are errors of omission, and errors made during

taxi operations would achieve the Board’s objectives as an alternative to the regulatory

change that was originally proposed. Therefore, Safety Recommendation A-94-3 was

classified “Closed—Acceptable Alternate Action.”

Safety Recommendation A-94-4 asked the FAA to 

Require that U.S. air carriers operating under 14 CFR Part 121 structure their

initial operating experience programs to include (1) training for check airmen in

enhancing the monitoring and challenging functions of captains and first officers;

(2) sufficient experience for new first officers in performing the nonflying pilot

role to establish a positive attitude toward monitoring and challenging errors made

by the flying pilot; and (3) experience (during initial operating experience and

annual line checks) for captains in giving and receiving challenges of errors. 

On April 26, 1994, the FAA stated that its actions in response to Safety

Recommendation A-94-3 addressed the issues referenced in this recommendation. On

July 6, 1994, the Safety Board reiterated that one intent of Safety Recommendation

A-94-4 was for air carriers to provide crewmembers undergoing initial operational

experience (IOE) with experience specifically in the PNF role. The Safety Board believed

that the FAA should, at the very least, provide guidance to air carriers on this issue in the

form of an AC.

On February 28, 1995, the FAA informed the Safety Board that, on January 3,

1995, AC 120-51B, “Crew Resource Management,” was issued to provide emphasis for

the PNF to monitor and challenge errors and for the PF to give and receive challenges of

errors. On April 24, 1995, the Safety Board expressed its disappointment that AC 120-51B
Factual Information 124 Aircraft Accident Report

made no reference to the structure of IOE, PNF experience in monitoring and challenging

errors during IOE and LOFT, or experience for captains in giving and receiving challenges

of errors.

On June 16, 1995, the FAA stated that, on April 21, 1995, it had issued a final rule

to amend the pilot qualification requirements for air carrier and commercial operators.

According to the FAA, the final rule requires that second-in-command pilots obtain

operating experience while performing the duties of a second-in-command under the

supervision of a qualified pilot check airman. Additionally, the FAA stated that it was

revising AC 120-51B to provide emphasis on the role of the PNF in monitoring and

challenging errors and for captains to gain experience in giving and receiving challenges

of errors. The FAA indicated that the revisions to the AC would emphasize the training of

check airmen so that they would be prepared to enhance the monitoring and challenging

functions of captains and first officers.

On August 29, 1995, the Safety Board stated that it was pleased that the FAA had

issued a final rule that required air carriers to provide newly qualified second-in-command

pilots with IOE while actually performing the duties of, rather than while observing, a

second-in-command pilot. The Board was also pleased that the FAA was revising

AC-120-51B. The Board believed that check airmen who receive training in enhancing the

monitoring and challenging functions of captains and first officers would be able to

provide more effective operating experience for newly qualified pilots if air carrier IOE

programs ensured that pilots receive sufficient experience performing PNF functions

while under check airman supervision.

On November 17, 1995, the FAA informed the Safety Board that it had revised

AC-120B. On January 16, 1996, the Safety Board stated that the revised AC’s reference to

training for check airmen in methods that could be used to enhance the monitoring and

challenging function of captains and first officers was responsive to Safety

Recommendation A-94-4 because the check airmen would apply their CRM skills during

IOE for new captains and first officers. Because the FAA’s revisions to AC 120-51B

satisfied the intent of Safety Recommendation A-94-4, it was classified “Closed—

Acceptable Alternate Action.”

1.18.5.3 National Aeronautics and Space Administration’s 

Flight Crew Decision-making Study

Researchers at the National Aeronautics and Space Administration’s (NASA)

Ames Research Center conducted a study that examined the Safety Board’s findings in its

1994 safety study (see section 1.18.5.1). The purpose of the NASA study was to analyze

the accident data to identify any contributing factors such as “ambiguous dynamic

conditions and organizational and socially-induced goal conflicts.”170

170 Orasanu, Judith, Martin, Lynne, and Davison, Jeannie. Errors in Aviation Decision Making: Bad

Decisions or Bad Luck? NASA Ames Research Center, Moffett Field, California. Presented to the Fourth

Conference on Naturalistic Decision Making, Warrenton, Virginia, May 29-31, 1998.
Factual Information 125 Aircraft Accident Report

The NASA researchers reexamined the 37 accidents included in the safety study to

determine the most common decision errors and any themes or patterns in the context

within which the errors occurred. NASA found that the most common decision errors

occurred when the flight crew decided to “continue with the original plan of action in the

face of cues that suggested changing the course of action.” The NASA study stated:

Clearly, more cognitive effort is needed to revise one’s understanding of a

situation or to consider a new course of action than sticking with the original plan

whose details have already been worked out.... It appears that evidence must be

unambiguous and of sufficient weight to prompt a change of plan.

With regard to ambiguity and its effect on situation assessment and decisionmaking, the NASA study stated: 

Cues that signal a problem are not always clear-cut. Conditions can deteriorate

gradually, and the decision maker’s situation assessment may not keep pace...a

recurring problem is that pilots are not likely to question their interpretation of a

situation even if it is in error. Ambiguous cues may permit multiple

interpretations. If this ambiguity is not recognized, the crew may be confident that

they have correctly interpreted the problem. Even if the ambiguity is recognized, a

substantial weight of evidence may be needed to change the plan being executed. 

The study noted that stress may limit the pilot’s ability to properly evaluate the

situation:

Reaching decision...requires projection and evaluation of the consequences of the

various options. If pilots are under stress, they may not do the required

evaluations.... Under stress, decision makers often fall back on their most familiar

responses, which may not be appropriate to the current situation.

Further, the NASA study determined that organizational and social pressures may

contribute to the high incidence of “plan continuation errors” by creating goal conflicts,

which may result in decision errors in the face of ambiguous cues and high-risk situations.

The study noted that organizational and social factors that have the potential to create goal

conflicts with safety include pressure for on-time arrival rates, fuel economy, and

avoidance of diversions to reduce passenger inconvenience.

The NASA study concluded that, to reduce pressures on pilots, operators “must be

willing to stand behind their pilots who take a safe course of action rather than a riskier

one, even if there is a cost associated.” The study noted that integrated flight displays that

present up-to-date information on dynamic variables, such as weather and traffic, could

reduce the ambiguity of events flight crews might encounter and that training to help flight

crews develop “strategies for choosing a course of action” would be beneficial.
Factual Information 126 Aircraft Accident Report

1.18.6 Previous Fatigue-Related Accidents 

The Safety Board has investigated several accidents in which fatigue was either

the cause or a contributing factor. A discussion of two such accidents follows.

Continental Express Jet Link Flight 2733

On April 29, 1993, Continental Airlines (d.b.a. Continental Express) Jet Link

flight 2733, an Embraer EMB-120RT, N24706, crashed at Pine Bluff, Arkansas, during a

forced landing and runway overrun at a closed airport.171 The flight was a scheduled

14 CFR 135 operation from Little Rock, Arkansas, to Houston, Texas. The 2 flight

crewmembers and 15 passengers were uninjured, and the flight attendant and

12 passengers received minor injuries. The accident occurred on the third day of a 3-day

trip sequence, and the accident flight was the seventh and last flight of the day.

As the airplane was climbing, the captain, who was the PF, increased pitch so that

the flight attendant could begin cabin service. The autoflight was set in pitch and heading

modes, contrary to company policy. The airplane stalled in IMC at 17,400 feet. Initial

recovery was at 6,700 feet. Because of an improper recovery procedure, a second stall

occurred, and recovery was at 5,500 feet. The left propeller shed three blades, the left

engine cowling separated, and the left engine was shut down in descent. Level flight could

not be maintained, and a forced landing was made. The captain overshot the final turn

because of controllability problems, and the airplane landed fast with 1,880 feet of wet

runway remaining. The airplane hydroplaned off the runway and received additional

damage. No preaccident malfunction was found. 

The Safety Board’s review of the captain's schedule revealed that the first day of

the trip involved 9.5 hours of duty time followed by 8.5 hours of rest time (a reduced rest

period). The second day of the trip involved 3.8 hours of duty time. The captain was off

duty at 1130 but did not go to sleep until between midnight and 0030.172 On the third day

of the trip, the captain awoke about 0500 for an early duty time. At the time of the

accident, the captain had been awake for about 11 hours. 

The first officer’s flight, duty, and crew rest schedules were the same as that of the

captain for the 3-day trip sequence. The first officer went to bed between 2300 and

midnight on the night before the accident and awoke about 0430 on the day of the

accident. The first officer had also been awake about 11 hours at the time of the accident. 

The Safety Board determined that the probable cause of the accident was the

captain’s failure to maintain professional cockpit discipline, his consequent inattention to

flight instruments and ice accretion, and his selection of an improper autoflight vertical

mode, all of which led to an aerodynamic stall, loss of control, and a forced landing.

171 National Transportation Safety Board. 1994. In-flight Loss of Control, Leading to Forced Landing

and Runway Overrun, Continental Express, Inc., Embraer EMB-120RT, N24706, Pine Bluff, Arkansas,

April 29, 1993. Aircraft Accident Report NTSB/AAR-94/02/SUM. Washington, DC.

172 All times for this accident are central standard time, based on a 24-hour clock.
Factual Information 127 Aircraft Accident Report

A factor contributing to the accident was fatigue induced by the flight crew’s failure to

properly manage provided rest periods.173

American International Airways Flight 808

On August 18, 1993, American International Airways (d.b.a. Connie Kalitta

Services, Inc.) flight 808, a Douglas DC-8-61, N814CK, was on a nonscheduled 14 CFR

Part 121 operation when it crashed in at the U.S. Naval Air Station at Guantanamo Bay,

Cuba.174 The cargo airplane collided with level terrain approximately 1⁄4 mile from the

approach end of runway 10 at Leeward Point Airfield after the captain lost control of the

airplane. The airplane was destroyed by impact forces and a postcrash fire, and the three

flight crew members—the only occupants aboard the airplane—received serious injuries.

The cargo airplane was on the last leg of a flight sequence that day from Atlanta, Georgia,

to Norfolk, Virginia, and then Guantanamo Bay.

The flight crew had been on duty about 18 hours and had flown approximately

9 hours.175 The captain did not recognize deteriorating flightpath and airspeed conditions

because of his preoccupation with locating a strobe light176 on the ground. The flight

engineer made repeated callouts regarding slow airspeed conditions. The captain initiated

a turn on final approach at an airspeed below the calculated approach speed of 147 knots

and less than 1,000 feet from the shoreline, and the captain allowed bank angles in excess

of 50° to develop. The stall warning stickshaker activated 7 seconds before impact and

5 seconds before the airplane reached stall speed. No evidence indicated that the captain

attempted to take proper corrective action at the onset of the stickshaker. The Safety Board

concluded that the substandard performance by this experienced pilot may have reflected

the debilitating influences of fatigue.

In its report on this accident, the Safety Board stated that three background factors

are commonly examined for evidence related to fatigue: cumulative sleep loss, continuous

hours of wakefulness, and time of day. The flight crew had received limited sleep in the 48

hours before the accident because of flight and duty time. Also, at the time of the accident,

the captain had been awake for 23.5 hours, the first officer for 19 hours, and the flight

engineer for 21 hours. In addition, the accident occurred about 1656 eastern daylight time

(based on a 24-hour clock), at the end of one of the two low periods in a person’s circadian

rhythm. The Board also considered the captain’s self-report (for example, his report of

173 Human fatigue in transport operations was listed as one of the Safety Board’s May 1999 Most Wanted

Transportation Safety Improvements. 

174 National Transportation Safety Board. 1994. Uncontrolled Collision With Terrain, American

International Airways Flight 808, Douglas DC-8-61, N814CK, U.S. Naval Air Station, Guantanamo Bay,

Cuba, August 18, 1993. Aircraft Accident Report NTSB/AAR-94/04. Washington, DC.

175 At the public hearing on this accident, the chief crew scheduler for American International Airways

testified that this flight assignment would have resulted in an accumulated flight time of 12 hours, which

was within the company’s “24-hour crew day policy.”

176 The strobe light was to be used as visual reference during the approach. The flight crew was not

advised, however, that the strobe light was inoperative.
Factual Information 128 Aircraft Accident Report

feeling “lethargic and indifferent” in the last period before the accident) in evaluating

whether fatigue was present.

The Safety Board determined that the probable cause of the accident was the

impaired judgment, decision-making, and flying abilities of the captain and the other

flight crewmembers because of the effects of fatigue; the captain’s failure to properly

assess the conditions for landing and maintaining vigilant situational awareness of the

airplane while maneuvering onto final approach; his failure to prevent the loss of airspeed

and avoid a stall while in the steep bank turn; and his failure to execute immediate action

to recover from a stall. Additional factors contributing to the cause of the accident

included the inadequacy of the flight and duty time regulations applied to 14 CFR Part 121

supplemental air carriers, international operations, and the circumstances that resulted in

the extended flight and duty hours and fatigue of the flight crewmembers.

1.18.6.1 Previous Safety Recommendations Regarding Fatigue 

On May 17, 1999, the Safety Board adopted a safety report entitled Evaluation of

U.S. Department of Transportation Efforts in the 1990s to Address Operator Fatigue.

177 In

its report, the Board noted that in 1989 it issued three recommendations to the DOT

addressing needed research, education, and revisions to hours-of-service regulations.178

The Board further noted that, since that time, it had issued more than 70 additional

recommendations aimed at reducing the incidence of fatigue-related accidents. The Board

stated that, even though the DOT and modal administrations had responded positively to

the recommendations addressing research and education, little action had occurred with

respect to revising the hours-of-service regulations. 

The safety report discussed the activities and efforts by the DOT and the modal

administrations to address operator fatigue and the resulting progress that has been made

over the past 10 years to implement the actions called for in the Safety Board’s fatiguerelated recommendations. The report also provided background information on current

hours-of-service regulations, fatigue, and the effects of fatigue on transportation safety. As a

result of its findings, the Safety Board issued Safety Recommendations I-99-1 and A-99-45. 

Safety Recommendation I-99-1 asked the DOT to

Require the modal administrations to modify the appropriate Codes of Federal

Regulations to establish scientifically based hours-of-service regulations that set

limits on hours of service, provide predictable work and rest schedules, and

177 National Transportation Safety Board. 1999. Evaluation of U.S. Department of Transportation Efforts

in the 1990s to Address Operator Fatigue. Safety Report NTSB/SR-99/01. Washington, DC.

178 Safety Recommendation A-89-1 asked the DOT to expedite a coordinated research program on the

effects of fatigue, sleepiness, sleep disorders, and circadian factors on transportation system safety. Safety

Recommendation A-89-2 asked the DOT to develop and disseminate educational material for transportation

industry personnel and management regarding shift work; work and rest schedules; and proper regimens of

health, diet, and rest. Safety Recommendation A-89-3 asked the DOT to review and upgrade regulations

governing hours of service for all transportation modes to ensure that they are consistent and that they

incorporate the results of the latest research on fatigue and sleep issues.
Factual Information 129 Aircraft Accident Report

consider circadian rhythms and human sleep and rest requirements. Seek

Congressional authority, if necessary, for the modal administrations to establish

these regulations.179

Safety Recommendation A-99-45 asked the FAA to

Establish within 2 years scientifically based hours-of-service regulations that set

limits on hours of service, provide predictable work and rest schedules, and

consider circadian rhythms and human sleep and rest requirements.

On July 15, 1999, the FAA indicated that it agreed with the intent of Safety

Recommendation A-99-45 and stated that, on December 11, 1998, it had issued NPRM

95-18, which proposed amending existing regulations to establish one set of duty period

limitations, flight time limitations, and rest requirements for flight crewmembers engaged

in air transportation. The FAA stated that the NPRM considered scientific data from

studies conducted by NASA relating to flight crewmember duty periods, flight times, and

rest and that Safety Recommendation A-99-45 would be included in this rulemaking

project. The FAA further indicated that its Aviation Rulemaking Advisory Committee was

tasked to review reserve issues related to the NPRM but was unable to agree on a

recommendation. The FAA indicated that it was conducting a risk assessment to

determine the probability of preventing future incidents related to fatigue and did not

know when a supplemental NPRM would be issued. However, the FAA stated that, in the

interim, it published a notice on June 15, 1999, indicating its intent to enforce the

regulations concerning flight time limitations and rest requirements. At an October 7,

1999, meeting with the Safety Board’s Chairman, the FAA Administrator indicated that a

final rule would not be issued within the next 2 years.

1.18.7 Flight Data Recorder Documentation

A digital flight data recorder (DFDR) records values for parameters related to the

operation of an airplane (for example, altitude, airspeed, and heading). The values are

recorded in a serial binary digital data stream that must be converted either to engineering

units or discrete states. The arrangement of the recorded values often varies among DFDR

systems; consequently, accurate conversion of the recorded values to their corresponding

engineering units or discrete states can be accomplished only when the configuration of

the data has been thoroughly documented.

1.18.7.1 Previous Safety Board Recommendations on Flight Data Recorder 

Parameter Verification and Documentation 

In the early 1970s, the Safety Board began issuing safety recommendations to

improve FDR parameter verification and documentation. In 1991, the Safety Board issued

two safety recommendations (A-91-23 and -24) to the FAA for developing a permanent

179 As of November 1999, the Safety Board had not received a response on this recommendation from

the DOT.
Factual Information 130 Aircraft Accident Report

policy for FDR maintenance and record-keeping. In 1997, after a series of accidents that

involved problems with extracting data from retrofitted FDRs, the Safety Board issued a

safety recommendation (A-97-30) that asked the FAA to publish an AC addressing the

certification and maintenance of FDRs.180

Safety Recommendation A-91-23 asked the FAA to

Issue permanent policy and guidance material for the continued airworthiness of

digital flight data recorder systems, stating that the make and model of the flight

data recorder and the make and model of the flight data acquisition unit, if

installed, must be maintained as part of each aircraft’s records, as well as at least

the following information for each parameter recorded:

• Location of parameter word (2 through 64 or 128).

• Assigned bits (1 through 12).

• Range (in engineering units when applicable). 

• Sign convention (for example, trailing edge up = +). 

• Type sensor (for example, synchro or low-level DC). 

• Accuracy limits (sensor input). 

• FAA requirement (that is, mandatory or not mandatory). 

• Subframe/superframe assignment: Documentation for engineering unit

conversion.

• General equation: Provide A0, A1, A2, and A3 for the equation Y = A0 +

A1X + A2X2 + A3X3, where Y = output in engineering units and X = input

in decimal or converted counts.

• Nonlinear parameters: Provide a sufficient number of data samples

(engineering units versus recorded decimal counts) to develop a conversion

algorithm that will accurately define the full range of the parameter.

• Discrete parameters: Status (that is, 1 = on, 0 = off).

Safety Recommendation A-91-24 asked the FAA to 

Require operators to maintain current information for each unique digital flight

data recorder configuration in its inventory using a single, universally adopted

format, such as that described in the standard being developed by Aeronautical

Radio, Inc. 

180 The Board encountered problems extracting data from retrofitted FDRs recovered from the following

accidents and incidents: Express One, Boeing 727, Orebro, Sweden, November 12, 1996; Millon Air,

Boeing 707, Manta, Ecuador, October 22, 1996; ValuJet, DC-9, Miami, Florida, May 11, 1996; ValuJet,

DC-9, Savannah, Georgia, February 28, 1996; ValuJet, DC-9, Nashville, Tennessee, February 1, 1996;

ValuJet, DC-9, Nashville, Tennessee, January 7, 1996; Millon Air, DC-8, Guatemala City, Guatemala, April

28, 1995; and Air Transport International, DC-8, Kansas City, Missouri, February 16, 1995. The lack of

adequate documentation of these FDR systems prevented accurate and complete readouts of the FDR data

and, consequently, a clear understanding of the circumstances surrounding the accidents.
Factual Information 131 Aircraft Accident Report

On May 9, 1991, the FAA stated that it was reviewing these safety

recommendations. On August 1, 1991, the Safety Board stated that it was disappointed

that the FAA failed to include any timetable for the completion of the review because

untimely or missing DFDR documentation was adversely affecting ongoing

investigations. The Board reemphasized its commitment to these recommendations,

stating that it would continue to work with the FAA and the aviation industry to

implement the recommendations.

On December 18, 1991, the FAA stated that it was planning to develop an AC to

address the installation and maintenance of DFDRs and flight data acquisition units

(FDAU). The FAA indicated that the AC would reference the appropriate regulatory

requirements and contain the universal documentation format for each DFDR aircraft

configuration and installation. The FAA further indicated that the baseline documents for

the AC would be the universal format being developed by Aeronautical Radio, Inc., and

the Board’s proposed FDR configuration documentation standard. 

On January 28, 1992, the Safety Board stated that it remained encouraged by the

FAA’s support for these safety recommendations. The Board believed that the FAA’s plan

to develop an AC that addresses the installation and maintenance of DFDR systems and

references a universal documentation standard was a step in the right direction. However,

the Board believed that the AC needed to be supplemented with permanent policy and

guidance material so that FAA inspectors would require that the AC be implemented. 

On April 22, 1994, the Safety Board stated that, in early 1993, FAA staff had

indicated that the proposed AC had not been developed because the FAA was waiting for

Aeronautical Radio, Inc., to publish the proposed documentation standard. Because

Aeronautical Radio was unable to commit the resources needed to publish the proposed

standard, the FAA proposed that the Board draft an AC that incorporated the draft

Aeronautical Radio documentation standard. Safety Board and FAA staffs subsequently

discussed and agreed on the principal elements of a draft AC based on the draft

Aeronautical Radio documentation standards. On October 18, 1993, the Board provided a

draft of the AC and DFDR documentation standards. However, the FAA made no progress

toward implementing Safety Recommendations A-91-23 and -24, even with the Board’s

draft AC. The Safety Board continued to believe that the actions requested in these

recommendations were essential and therefore urged the FAA to take the necessary actions. 

On March 3, 1997, the FAA stated that it included information regarding the

installation and maintenance of DFDRs and FDAUs in Notice N8110.65, “Policy and

Guidance for the Certification and Continued Airworthiness of Digital Flight Data

Recorder Systems.” According to the FAA, the notice referenced the appropriate

regulatory requirements and contained the universal documentation format for each

DFDR aircraft configuration and installation. The FAA stated that the universal format

developed by Aeronautical Radio, Inc., and the Board’s proposed FDR configuration

documentation standard were used as baseline documents for the notice.

On July 10, 1998, the Safety Board noted its disappointment that the AC had still

not been completed. The Board stated that inclusion of guidance relating to FDR
Factual Information 132 Aircraft Accident Report

maintenance documentation (which was addressed in FAA Notice N8110.65) in this AC

would satisfy the intent of Safety Recommendations A-91-23 and -24, which had been

issued 7 years earlier. The Board was concerned that the AC might still not be produced in

a timely manner. Accordingly, the Safety Board classified Safety Recommendations

A-91-23 and -24 “Open—Unacceptable Response” pending the FAA’s completion of

the AC. 

Safety Recommendation A-97-30 asked the FAA to

Complete the planned flight data recorder (FDR) advisory circular (AC) to define

FDR certification requirements and FDR maintenance requirements, and

incorporate the FDR documentation standards contained in Notice N8110.65. The

AC should be released no later than January 16, 1998.

On July 14, 1997, the FAA stated that it agreed with the intent of this safety

recommendation. The FAA also stated that it would complete the AC for FDR

certification and maintenance requirements by January 1998.

On July 10, 1998, the Safety Board stated its disappointment that the AC,

promised by the FAA to be issued by January 1998, had not been completed. The Board

was concerned that the AC would not be produced in a timely manner. The Board stated

that the guidance contained in this AC was essential to avoid widespread retrofit

problems.181 Pending the FAA’s completion of the AC, the Safety Board classified Safety

Recommendation A-97-30 “Open—Unacceptable Response.” 

1.18.7.1.1 Digital Flight Data Recorder Advisory Circular 

On October 5, 1999, AC 20-141, “Airworthiness and Operational Approval of

Digital Flight Data Recorder Systems,” was issued. The purpose of the AC is to provide

“guidance on design, installation, and continued airworthiness of Digital Flight Data

Recorder Systems.” Appendix 1 to the AC, titled “Standard Data Format for Digital Flight

Data Recorder Data Stream Format and Correlation Documentation,” provides “a standard

for the data stream format and correlation documentation that operators must maintain to aid

accident investigators in interpreting recorded flight data.” The appendix details how to

develop a document for each airplane that would provide in detail the information that

would assist Safety Board investigators in transcribing each parameter recorded by an FDR.

1.18.7.2 International Guidance Regarding the Documentation of 

Flight Data Recorder Parameters

ICAO provides guidance to Member States regarding the documentation of FDR

parameters. ICAO Annex 6, “International Standards and Recommended Practices—

Operation of Aircraft, Part I—International Commercial Air Transport—Aeroplanes,”

includes Attachment D, Flight Recorders. Section 3 of the attachment, “Inspections of

flight data and cockpit voice recorder systems,” provides guidance on the continued

181 The FAA adopted rulemaking to require airlines to retrofit FDRs on most U.S.-registered aircraft.
Factual Information 133 Aircraft Accident Report

airworthiness of FDR systems, including how to conduct annual checks of every FDR

parameter. Paragraph 3.2(c) states that “a complete flight from the FDR should be

examined in engineering units to evaluate the validity of all recorded parameters.” In

addition, paragraph 3.2(d) states that “the readout facility should have the necessary

software to accurately convert the recorded values to engineering units and to determine

the status of discrete signals.” 

1.18.8 Special Airport Criteria and Designation

On October 19, 1996, Delta Air Lines flight 554, a McDonnell Douglas MD-88,

N914DL, struck the approach light structure at the end of the runway deck during the

approach to land on runway 13 at LaGuardia Airport in Flushing, New York.182 IMC

conditions prevailed for the ILS DME approach. None of the two flight crewmembers and

three flight attendants were injured, but 3 of the 58 passengers received minor injuries.

The airplane sustained substantial damage.

According to the first officer of the flight, the approach to runway 13 requires

landing over water, a 250-foot DH, and an offset localizer, and the approach to the

opposite direction runway (31) requires maneuvering an airplane at high bank angles close

to the ground. However, LaGuardia was not designated by the FAA as a special airport

under 14 CFR Section 121.445.183 That section, titled “Pilot in command airport

qualification: Special areas and airports,” states the following:184

(a) The [FAA] Administrator may determine that certain airports (due to items

such as surrounding terrain, obstructions, or complex approach or departure

procedures) are special airports requiring special airport qualifications and that

certain areas or routes, or both, require a special type of navigation qualification.

(b) ...no certificate holder may use any person, nor may any person serve, as pilot

in command to or from an airport determined to require special airport

qualifications unless, within the preceding 12 calendar months:

(1) The pilot in command or second in command has made an entry to that

airport (including a takeoff and landing) while serving as a pilot flight

crewmember; or

(2) The pilot in command has qualified by using pictorial means acceptable to

the Administrator for that airport.

The Safety Board’s investigation of the accident concluded, among other things,

that the FAA’s guidance on special airports was not sufficiently specific about criteria and

182 National Transportation Safety Board. 1997. Descent Below Visual Glidepath and Collision With

Terrain, Delta Air Lines Flight 554, McDonnell Douglas MD-88, N914DL, LaGuardia Airport, New York,

October 19, 1996. Aircraft Accident Report NTSB/AAR-97/03. Washington, DC.

183 The first officer indicated his belief that LaGuardia should be designated as a special airport and that

approaches to runways 13 and 31 were worthy of special pilot qualification requirements.

184 This rule was adopted in June 1980.
Factual Information 134 Aircraft Accident Report

procedures for designation of special airports; therefore, the FAA’s guidance might not

always be useful to air carriers operating in and out of special airports. The Board also

concluded that the requirements for special airport pilot qualifications might not be

sufficient to ensure that qualified pilots have been exposed to the runways and/or

approaches that make those airports “special.”

As a result of its findings, the Safety Board issued Safety Recommendations

A-97-92 through -94 on August 25, 1997. Safety Recommendations A-97-92 through -94

asked the FAA to 

Expedite the development and publication of specific criteria and conditions for

the classification of special airports; the resultant publication should include

specific remarks detailing the reason(s) an airport is determined to be a special

airport and procedures for adding and removing airports from special airport

classification. (A-97-92)

Develop criteria for special runways and/or special approaches, giving

consideration to the circumstances of this accident and any unique characteristics

and special conditions at airports...and include detailed pilot qualification

requirements for designated special runways or approaches. (A-97-93)

Once criteria for designating special airports and special runways and/or special

approaches have been developed, as recommended in Safety Recommendations

A-97-92 and -93, evaluate all airports against that criteria and update special

airport publications accordingly. (A-97-94)

On November 13, 1997, the FAA stated that it was developing a flight standards

handbook bulletin and revising AC 121.445, “Pilot-In-Command Qualifications for

Special Area/Routes and Airports, Federal Aviation Regulations (FAR) Section

121.445.”185 The FAA indicated that the bulletin and AC would address the issues

discussed in the recommendations. The FAA anticipated that these documents would be

issued in April 1998. On August 17, 1998, the Safety Board stated that, pending the FAA’s

completion of these documents, Safety Recommendations A-97-92 through -94 were

classified “Open—Acceptable Response.”

On September 21, 1999, the FAA stated that AC 121.445 was undergoing internal

coordination and should be published in the Federal Register by November 1999. The

FAA indicated that it would proceed with issuing the flight standards handbook bulletin as

soon as the AC was completed. According to the FAA, both documents were expected to

be issued by February 2000.

185 The version of AC 121.445 that was in effect at the time of the accident was dated June 1990.
135 Aircraft Accident Report

2. Analysis

2.1 General

The three Korean Air flight 801 flight crewmembers were properly certificated

and qualified in accordance with applicable Korean Civil Aviation Bureau (KCAB) and

U.S. Federal regulations, International Civil Aviation Organization (ICAO) standards, and

Korean Air company requirements. No evidence indicated that any medical factors

affected the flight crew’s performance. 

The airplane was properly certificated, equipped, and maintained in accordance

with applicable KCAB and ICAO standards and Korean Air company procedures. The

airplane was authorized to operate in U.S. airspace under the provisions of 14 Code of

Federal Regulations (CFR) Part 129. The weight and balance of the airplane were within

the prescribed limits for landing. No evidence indicated that the airplane experienced

preimpact failures of its structures, flight control systems, or engines.

ATC personnel involved with the flight were properly certificated and qualified as

full-performance level controllers. ATC radar and communications equipment were found

to be functioning properly, although the FAA-maintained minimum safe altitude warning

(MSAW) system had been intentionally inhibited.

This analysis examines the accident scenario, including weather factors, flight

crew performance and decision-making, and other relevant factors during the approach, as

well as flight crew fatigue issues. The analysis also examines the performance of ATC

personnel, the effects of the MSAW system’s intentional inhibition, and the timeliness and

effectiveness of the emergency response to the accident site. In addition, the analysis

examines Korean Air’s flight crew simulator training, KCAB oversight of Korean Air’s

flight training programs, FAA oversight of Korean Air’s operations under 14 CFR

Part 129, and international efforts to reduce the number of controlled flight into terrain

(CFIT) accidents.

2.2 Weather Factors on the Approach

A review of weather data indicated that variable clouds and scattered rain showers

associated with a weak eastward-moving low-pressure trough were affecting the Guam

area about the time of the accident and that the showers increased in intensity as they

moved over the higher terrain of the island. However, Safety Board interviews with flight

crewmembers who flew into Guam before and after the flight 801 accident indicated that

the lights of the island were occasionally visible from as far away as 150 nm. In addition,

CVR data indicated that the accident flight crew made visual contact with the island about

16 minutes before the accident (about 0126:25) when the flight engineer stated “it’s

Guam, Guam.”
Analysis 136 Aircraft Accident Report

On the basis of weather data and witness statements, flight 801 was likely to have

initially encountered variable scattered to broken cloud layers below 5,000 feet msl during

the final approach to Guam. Ground lights were likely occasionally visible along the

coastline, and it is probable that only scattered clouds existed below the airplane in the

vicinity of the FLAKE intersection, located 7 DME from the NIMITZ VOR (UNZ). 

Doppler radar data indicated that a heavy to very heavy rain shower was centered

over higher terrain about 4 nm southwest of the airport (along the approach corridor)

about the time of the accident. Weather data indicated that, although the Apra Harbor area

(about 5 DME on the approach course) would likely have been visible to the flight crew as

the airplane descended through 2,000 feet msl, the airplane would have entered clouds and

light precipitation shortly after passing Apra Harbor. Radar data indicated that the flight

likely experienced rain of continuously increasing intensity as the airplane proceeded

inbound toward the airport and that the flight encountered very heavy precipitation for a

short time near the outer marker (GUQQY). About 0141:48, when the airplane was near

the outer marker, the CVR recorded the captain stating “wiper on.” 

Although a hunter on Nimitz Hill stated that it was not raining at the time he

observed the flight overhead, Doppler radar data indicated light to moderate rain shower

activity between Nimitz Hill and the airport. Therefore, on the basis of weather radar and

observation data, the Safety Board concludes that, after the flight crew made an initial

sighting of Guam, Korean Air flight 801 encountered instrument meteorological

conditions (IMC) as the flight continued on its approach to Guam International Airport.

Further, the Safety Board concludes that, although flight 801 likely exited a heavy rain

shower shortly before the accident, the flight crew was still not able to see the airport

because of the presence of another rain shower located between Nimitz Hill and the

airport.

2.3 Accident Sequence

2.3.1 Description of the Approach and Required Flight Crew 

Procedures

The instrument landing system (ILS) glideslope (GS) inoperative, or localizer

(LOC)-only, approach to runway 6L at Guam International Airport required the flight

crew to maintain at least 2,000 feet from the FLAKE intersection (7 DME from the UNZ

VOR) to the GUQQY (outer marker) final approach fix (FAF), which was located

1.6 DME from the UNZ VOR. After passing GUQQY, the crew was required to maintain

at least 1,440 feet msl until passing the UNZ VOR. After passing the UNZ VOR, the next

step-down fix was to 560 feet (the minimum descent altitude [MDA]), and the flight crew

was required to maintain at least this altitude while counting up to 2.8 DME (the missed

approach point [MAP]) from the UNZ VOR.

To properly fly this approach, the flying pilot’s navigation receiver would need to

be tuned to the localizer frequency, and the nonflying pilot’s navigation receiver would
Analysis 137 Aircraft Accident Report

need to be tuned to the UNZ VOR to provide the pilots with DME information for

FLAKE, GUQQY, and the MAP and allow them to identify station passage over the UNZ

VOR. Station passage over UNZ would be marked by the following instrument

indications: the TO/FROM indicator in the first officer’s horizontal situation indicator

(HSI) would have changed from TO to FROM, and the No. 2 (double) pointer in the

captain’s and first officer’s radio magnetic indicator would have swung from pointing

forward to aft. Although station passage is not defined by DME, station passage over the

UNZ VOR would have been indicated by a DME countdown to near zero and then a count

up as the airplane continued away from UNZ to runway 6L.

To use the autopilot and flight director (FD) during a nonprecision approach, the

flying pilot would have set the Nav Mode Switch to VOR/LOC on the glareshield

instrument panel once the airplane was established on the intercept heading to the

localizer outside the FAF. The FD and autopilot flight mode annunciator (FMA) on the

pilots’ instrument panels would then indicate NAV armed and GS blank.186 After localizer

capture, the pilots’ and the autopilot’s FMAs would indicate NAV capture,187 and the GS

would remain blank. The autopilot would turn the airplane as needed to track the localizer.

(Although the nonflying pilot’s navigation receiver would be tuned to the VOR, a different

frequency, that pilot’s FMA would also indicate NAV capture because the UNZ 243°

radial approximately overlays the localizer.) The FD command bars on the captain’s and

the first officer’s instruments would provide left and right roll commands to maintain a

capture on the respective courses.

When the airplane was descending, the flying pilot would normally have reset the

altitude selector to the next (lower) altitude target and moved the VERT SPEED (vertical

speed) wheel to position the airplane in about a 1,000-feet-per-minute rate of descent to

reach the next crossing altitude. The FD pitch command bars would move up and down to

provide guidance to maintain the desired rate of descent. (In a precision approach, the

command bars would provide guidance to maintain the glideslope; in nonprecision

approaches, they provide guidance to maintain the desired vertical speed.) Once the

airplane had reached the altitude set in the altitude selector, the FDs and autopilot would

capture and maintain that altitude. At no time during the localizer approach would the

flight crew have armed the autopilot or FDs to capture a glideslope signal or have

referenced or attempted to track any glideslope needle indications.

2.3.2 Flight 801’s Premature Descent

The Combined Center/Radar Approach Control (CERAP) controller vectored

flight 801 to join the runway 6L localizer course between the FLAKE intersection and the

GUQQY outer marker/1.6 DME fix. Although the flight was restricted to no lower than

2,000 feet msl in that portion of the localizer-only approach procedure (until crossing the

GUQQY outer marker), flight 801 descended below 2,000 feet about 1.9 nm before

reaching the outer marker. 

186 Armed is indicated with white letters on a black background. Blank is indicated by an absence of letters.

187 Capture is indicated with black letters on a green background.
Analysis 138 Aircraft Accident Report

Further, although the approach procedure specified that at least 1,440 feet msl

should be maintained after passing the GUQQY outer marker and until passing the UNZ

VOR, flight 801 descended below 1,440 feet about 2.1 DME before reaching the UNZ

VOR. (None of the indications of UNZ station passage would have been presented on the

flight crew’s instrument panels at any time before impact.)

CVR information indicated that the captain was flying the airplane on autopilot

during the approach. As flight 801 descended on the approach, the captain twice

commanded the entry of lower altitudes into the airplane’s altitude selector before the

airplane had reached the associated step-down fix. After the captain heard the first officer

call out “approaching fourteen hundred [feet]” about 0140:33, as the airplane was passing

5 DME at 2,400 feet msl,188 the captain directed the first officer to reset the altitude

selector to 1,440 feet, replacing the step-down altitude of 2,000 feet before the autopilot

had captured that altitude or reached the GUQQY outer marker/1.6 DME fix. Further,

about 0141:33, with the flight neither having leveled off at 1,440 feet msl nor reached the

UNZ VOR step-down fix, the captain instructed the first officer to set 560 feet, the MDA,

in the altitude selector. 

The altitude selector provides the basis for the altitude alert’s aural annunciations

and the autopilot’s altitude capture functions. The captain’s premature orders to reset the

altitude selector indicated that he had lost awareness of the airplane’s position along the

final approach course. Therefore, as a result of the captain’s commanded input to the

altitude selector, the autopilot continued to descend the airplane prematurely through the

2,000- and 1,440-foot intermediate altitude constraints of the approach procedure. The

CVR comments indicated no awareness by the captain that the airplane was descending

prematurely below the required intermediate altitudes.

2.4 Flight Crew Performance

2.4.1 The Captain’s Performance of the Approach

2.4.1.1 Approach Briefing

Korean Air cockpit procedures call for an approach (landing) briefing189 before

descent. Also, company training instructs the flying pilot to conduct an approach briefing

before descent. According to the Korean Air 747 landing briefing checklist card and

testimony by Korean Air officials during the Safety Board’s public hearing, this briefing

should include a discussion of weather conditions, a review of the instrument approach

188 It is not clear why the first officer made this callout at this altitude. It is possible that the first officer

may have intended the callout to mean that only 1,000 feet remained before reaching the 1,440-foot stepdown altitude, or he may have confused 2,400 feet with 1,400 feet on the altimeter. It is also possible that the

first officer may have believed that the DME was located on the airport and that the airplane was

approaching a DME value at which the airplane could descend to 1,440 feet. (See section 2.4.1.3.2 for a

discussion about possible DME confusion.)

189 The approach briefing is called a “landing briefing” on the Korean Air checklist card.
Analysis 139 Aircraft Accident Report

procedure, details of the approach’s execution (including the minimum safe altitude,

approach frequency and approach course, the runway touchdown zone elevation, and the

missed approach procedure), crew actions and callouts, and any abnormal configurations

or conditions. 

CVR information indicated that the captain briefed a visual approach in his

approach briefing, which he referred to as a “short briefing.” However, the captain also

briefed some elements of the localizer-only instrument approach, indicating that he

intended to follow that approach as a supplement or backup to the visual approach.

Specifically, the captain’s briefing included a reminder that the glideslope was inoperative,

some details of the radio setup, the localizer-only MDA, the missed approach procedure,

and the visibility at Guam (stated by the captain to be 6 miles). However, the captain did

not brief other information about the localizer-only approach, including the definitions of

the FAF and step-down fixes and their associated crossing altitude restrictions or the title,

issue, and effective dates of the approach charts to be used. The Safety Board notes that

the landing briefing checklist did not specifically require the captain to brief the fix

definitions, crossing altitudes, or approach chart title and dates,190 although it would have

been good practice to do so. 

Further, according to public hearing testimony by a Korean Air instructor pilot,

company pilots were trained to conduct a more detailed briefing than the one specified in

the landing briefing checklist for a nonprecision approach, such as the localizer approach

to runway 6L at Guam. According to the instructor pilot, this more detailed briefing

included a discussion of the “instrument approach in detail” and a discussion of the “stepdown altitudes and how they were determined.” The Safety Board notes that this

information is essential for a nonprecision approach briefing.

The Safety Board also notes that the captain did not brief the first officer and flight

engineer on how he would fly the descent (including his planned autopilot/FD modes and

his plan to fly either a constant angle of descent or a series of descents and level-off

altitudes associated with the step-down fixes), and he did not discuss go-around decision

criteria. Further, although not specifically required, it would have been prudent for the

captain to note the need for special caution in the UNZ VOR area (which he had described

as a “black hole” in his approach briefing to another first officer about 1 month earlier). 

The Safety Board further notes that, in this case, a thorough briefing was

especially important because the accident captain and first officer were flying together for

the first time, which is a situation that has been linked to flight crew-involved accidents.191

According to recent human factors research, a good briefing is important to develop a

“shared mental model” to ensure “that all crew members are solving the same problem

and have the same understanding of priorities, urgency, cue significance, what to watch

out for, who does what, and when to perform certain activities.”192 The Safety Board

190 Testimony by Korean Air officials at the Safety Board’s public hearing indicated that these items were

taught in company flight crew training. 

191 National Transportation Safety Board. 1994. A Review of Flightcrew-Involved Major Accidents of

U.S. Air Carriers, 1978 Through 1990. Safety Study NTSB/SS-94/01. Washington, DC, pp. 40-41.
Analysis 140 Aircraft Accident Report

concludes that, by not fully briefing the instrument approach, the captain missed an

opportunity to prepare himself, the first officer, and the flight engineer for the relatively

complex localizer-only approach and failed to provide the first officer and flight engineer

with adequate guidance about monitoring the approach; therefore, the captain’s approach

briefing was inadequate.

2.4.1.2 Expectation of a Visual Approach and Role of the Guam 

Airport Familiarization Video

The Safety Board notes that, when the captain flew to Guam about 1 month before

the accident, he executed a routine ILS approach to runway 6L in good visibility, with a

scattered cumulous buildup. Further, the most current ATIS information available to the

accident flight crew indicated that visual conditions (scattered cloud decks and 7-mile

visibility) existed at the airport. Korean Air’s Guam airport familiarization video, which

the captain and first officer had viewed in July 1997, noted that weather conditions in

Guam allowed visual approaches most of the year and that, even though IMC is likely

during the rainy season from June to November, “you [the pilot] will be guided from over

Apra Harbor to the localizer. You will then perform a visual approach....” Thus, the

captain may have assumed that conditions for the flight 801 approach would be similar to

those he experienced about 1 month earlier. The captain’s anticipation of a visual approach

probably became a strong expectation after the flight crew’s early visual sighting of

Guam. Although the captain would likely have recognized the possibility of flight through

clouds as the airplane descended from its cruise altitude, he may have assumed that the

visual approach slope indicator (VASI) system would be in sight after the flight was

vectored onto final approach by the CERAP controller. The VASI system would have

provided visual guidance for a constant angle of descent that safely cleared obstacles.

As previously discussed, the captain’s landing briefing included references to his

expectation of visual conditions at the airport as well as an abbreviated and inadequate

briefing for the localizer-only approach. The Safety Board concludes that the captain’s

expectation of a visual approach was a factor in his incomplete briefing of the localizer

approach. The Board is aware that it is a common practice among air carrier pilots to

abbreviate the briefing for a backup instrument approach when a visual approach is

expected. Although there may be little benefit to fully briefing a backup instrument

approach in daylight conditions when no appreciable possibility of encountering IMC

exists, the Safety Board concludes that, for flights conducted at night or when there is any

possibility that IMC may be encountered, the failure to fully brief an available backup

instrument approach compromises safety. Therefore, the Safety Board believes that the

FAA should require principal operations inspectors (POI) assigned to U.S. air carriers to

ensure that air carrier pilots conduct a full briefing for the instrument approach (if

available) intended to back up a visual approach conducted at night or when IMC may be

encountered. 

192 Orasanu, J. “Decision-making in the Cockpit.” In Cockpit Resource Management. 1993. Ed.

E.L. Weiner, B.G. Kanki, and R.L. Helmreich. San Diego: Academic Press, p. 159.
Analysis 141 Aircraft Accident Report

The Safety Board notes that, although Guam was not a designated special airport

requiring special training or familiarization by flight crews, Korean Air encouraged its

flight crews to view the airport familiarization video. However, the Guam familiarization

video gave only a generalized description of the topography of the island of Guam.

Although the video mentioned some of the obstacles near the approach course, it did not

specifically state that the UNZ VOR was located on a hill, the DME was not colocated

with the localizer, or the final approach segment was over hilly or mountainous terrain.

Even though the airport familiarization video accurately identified some

landmarks and advised pilots not to fly over a residential area and a Naval hospital (for

noise abatement), the Safety Board also notes with concern that the video contained no

discussion of factors that made operations into Guam challenging, such as the high terrain

along the approach course or in the vicinity of the airport. Further, the presentation did not

describe the complexity of the Guam nonprecision approaches, including the multiple

step-down fixes, the use of two separate navigation facilities (the localizer and the VOR),

and the countdown/count up DME procedure.

The Safety Board concludes that the Korean Air airport familiarization video for

Guam, by emphasizing the visual aspects of the approach, fostered the expectation by

company flight crews of a visual approach and, by not emphasizing the terrain hazards and

offset DME factors, did not adequately prepare flight crews for the range of potential

challenges associated with operations into Guam. Thus, the Safety Board believes that the

KCAB should require Korean Air to revise its video presentation for Guam to emphasize

that instrument approaches should also be expected and describe the complexity of such

approaches and the significant terrain along the approach courses and in the vicinity of the

airport. 

The Safety Board addressed the issue of the classification of special airports and

approaches to certain airports in connection with its investigation of the October 19, 1996,

accident involving Delta Air Lines flight 554, an MD-88, at LaGuardia Airport in New

York. On August 25, 1997, the Board issued Safety Recommendations A-97-92 through

-94, asking the FAA to develop and publish “specific criteria and conditions” for the

classification of special airports (including special runways and/or special approaches)

and use these criteria to evaluate all airports and “update special airport publications.” On

November 13, 1997, the FAA responded that it was revising Advisory Circular (AC)

121.445, “Pilot-in-Command Qualifications for Special Area/Routes and Airports,” and

that the revision would address the issues discussed in the safety recommendations. On

August 17, 1998, the Board classified Safety Recommendations A-97-92 through -94

“Open—Acceptable Response” pending completion of the AC. The Board recognizes that

the FAA’s eventual evaluation of Guam against the newly developed criteria might result

in its classification as a special airport. 

The Safety Board further recognizes that, because the captain flew into Guam and

viewed the Guam airport familiarization video during July 1997, he would have been

authorized to conduct the accident flight even if Guam had been classified as a special

airport. Nonetheless, the Safety Board concludes that the challenges associated with

operations to Guam International Airport support its immediate consideration as a special
Analysis 142 Aircraft Accident Report

airport requiring special pilot qualifications. Therefore, the Safety Board believes that the

FAA should consider designating Guam International Airport as a special airport requiring

special pilot qualifications. 

2.4.1.3 Possible Explanations for the Approach Conducted

2.4.1.3.1 Confusion About Status of Glideslope

Despite several indications that the flight crew was aware that the glideslope was

inoperative, in the last 2 1⁄2 minutes of the flight (beginning shortly after the airplane was

established on the approach), the CVR recorded a series of conflicting flight crew

comments concerning the operational status of the glideslope. About 0139:55, the flight

engineer asked, “is the glideslope working?” The captain responded, “yes, yes it’s

working.” About 0139:58, an unidentified voice in the cockpit stated, “check the

glideslope if working?” One second later, an unidentified voice in the cockpit stated, “why

is it working?” About 0140:00, the first officer responded, “not useable.” About 0140:22,

an unidentified voice in the cockpit stated, “glideslope is incorrect,” followed by the

captain’s statement, “since today’s glideslope condition is not good, we need to maintain

one thousand four hundred forty [feet].” However, about 0141:46, after the airplane

crossed the GUQQY outer marker (1.6 DME from the VOR), the captain again stated,

“isn’t glideslope working?” 

The Safety Board considered whether the flight crew might have misinterpreted

some cockpit instrumentation indications as a valid glideslope capture signal. During the

localizer approach into Guam, both pilots’ HSIs would have appeared centered; the

captain’s would have captured the localizer, and the first officer’s would have captured the

VOR radial. With VOR/LOC selected, the localizer captured, and the pitch commands set

to VERT SPEED (the most likely setting), the captain’s FD command bars would have

shown some vertical and horizontal movement, similar to an FD that was responding to a

captured localizer and glideslope. However, the raw data glideslope needles on the attitude

director indicator (ADI) and HSI would not have been affected by the VERT SPEED

setting; therefore, the captain’s ADI and HSI glideslope needles should have been covered

by “off” flags.193 Further, there would have been no glideslope capture annunciator on the

GS bar of the FMA on top of the captain’s and first officer’s instrument panels. 

The Safety Board also considered whether the flight crewmembers might have

observed intermittent movement of the glideslope needles during the approach, thereby

creating or adding to their confusion about the glideslope. An FAA navigation expert

testified at the Safety Board’s public hearing that spurious radio signals could cause a

sporadic or intermittent glideslope indicator deviation in the absence of a valid glideslope

signal. However, he stated that the glideslope off flag would still appear on the HSI and

ADI glideslope needles and that, when the off flag appears, any movement of the

glideslope needle should be considered unreliable. Postaccident testing by Korean Air and

the KCAB confirmed that an airplane’s glideslope receiver could be affected by spurious

193 The Safety Board notes that the raw data localizer and glideslope needles and off flags on the first

officer’s ADI and HSI would have been out of view because his navigation receiver was tuned to the VOR.
Analysis 143 Aircraft Accident Report

radio signals when no valid glideslope signal was being transmitted. The tests

demonstrated that spurious signals could cause movement of the glideslope needle and

that, when the receiver was subjected to a steady signal, retraction of the off flag was also

possible. However, the Safety Board notes that these tests were conducted with an airplane

on the ground and that the airplane’s navigational receiver was subjected to extreme signal

modulations transmitted very near the airplane’s antenna. These conditions are not likely

to be encountered by an airplane on an actual instrument approach.

The Safety Board also notes that the flight crew of a Boeing 727 reported

glideslope anomalies on August 5, 1997, while executing the localizer-only approach to

runway 6L at Guam.194 (The purpose of the flight was to test a newly installed GPS.)

However, the captain of the 727 stated that he thought the glideslope anomaly might have

been caused by the GPS wiring installation. Further, the first officer stated that he and the

captain “never thought twice” about the glideslope indications because they knew that the

glideslope was inoperative. The Board’s investigation into the 727’s maintenance history

indicated that, in the weeks after the test flight, several cockpit navigational displays,

including the first officer’s HSI and ADI, were repeatedly removed and replaced by

maintenance personnel because of anomaly reports written up by flight crews. The

maintenance documents indicated that the cockpit display problems were the result of

integrating the new GPS with the existing cockpit displays. 

Although it is possible that spurious radio signals caused some erratic movement

of the glideslope needles on the accident captain’s HSI and ADI, it is unlikely that the

accident airplane’s navigation receivers could have been subjected to a steady spurious

signal of a duration that would have resulted in a continuous glideslope needle activation

and flag retraction over a period of minutes and several miles of aircraft motion. Thus, the

presence of the off flags over the glideslope needles at some times and the absence of

FMA glideslope capture indicators on the captain’s and first officer’s instrument panels

should have been sufficient to convince the flight 801 flight crew to disregard the

glideslope indications. Even if the flight crewmembers did see a continuous glideslope

needle activation and flag retraction, it would not have been prudent or reasonable for

them to rely on a glideslope signal of any sort when the glideslope had been reported to be

unusable. (Korean Air officials stated that flight crews were trained not to use navigational

aids, including glideslopes, that were reported to be unreliable or unusable). Therefore, the

Safety Board concludes that, although the captain apparently became confused about the

glideslope’s status, the flight crew had sufficient information to be aware that the

glideslope was unusable for vertical guidance and should have ignored any glideslope

indications while executing the nonprecision localizer-only approach.

The Safety Board notes that, when a glideslope signal is not generated by the

transmitter (resulting in an open frequency channel), an airborne glideslope receiver will

continue to seek a glideslope signal, although navigation receiver filters are designed to

block most spurious radio signals. The postaccident testing conducted by Korean Air and

194 The Boeing 727 flight crew stated that no glideslope flags were visible and that the ADI glideslope

needle was “centered.”
Analysis 144 Aircraft Accident Report

the KCAB involved the glideslope receiver; however, the Safety Board concludes that

navigation receivers, including glideslope receivers, may be susceptible to spurious radio

signals. Therefore, the Safety Board believes that the FAA should disseminate information

to pilots, through the Aeronautical Information Manual, about the possibility of

momentary erroneous indications on cockpit displays when the primary signal generator

for a ground-based navigational transmitter (for example, a glideslope, VOR, or

nondirectional beacon [NDB] transmitter) is inoperative. Further, this information should

reiterate to pilots that they should disregard any navigation indication, regardless of its

apparent validity, if the particular transmitter was identified as unusable or inoperative.

2.4.1.3.2 Confusion About Location of DME

About 0140:37, when the airplane was at 2,400 feet msl and descending at 1,000

feet per minute, the captain stated, “since today’s glideslope condition is not good, we

need to maintain one thousand fourteen hundred forty [feet]. please set it.” This statement

suggests that the captain was attempting to comply with the restrictions of the localizeronly approach and believed that he had passed the GUQQY step-down fix. However, the

CVR recorded no discussion between the captain and the first officer about DME values

or their position in relation to the next step-down fix, the VOR, or the airport. 

The Safety Board considered whether the flight crew might have confused the

configuration of the runway 6L localizer approach with one in which the DME is located

on the airport. A review of the flight crew’s training records showed that the nonprecision

approaches incorporating DME provided to the flight crew during training and check rides

had the DME located on the airport. A countdown/count up DME procedure, which is

rarely encountered on a localizer procedure, was not included in any of the Korean Air

simulator training scenarios. If the flight crewmembers had the misconception that the

DME information referred to the distance from the airport, they might have believed that

the airplane was much closer to the airport than it actually was (the DME was located

3.3 nm southwest of the airport) and that the airplane was well above the minimum

altitudes for the intermediate step-down fixes and thus ready to descend directly to the

MDA. If the captain had this misconception, it could explain why he flew the airplane and

commanded altitude selections as though he believed he was at or above the altitude

constraint for each navigational fix along the approach. If the other flight crewmembers

shared this misconception, it could explain why they failed to challenge the captain’s

premature descents below 2,000 and 1,440 feet. 

However, this scenario suggests strongly that the captain was not noting the

definitions of the navigational fixes on the approach chart, which were clearly defined as

DME values.195 Thus, the Safety Board concludes that the captain may have mistakenly

believed that the airplane was closer to the airport than its actual position; however, if the

captain conducted the flight’s descent on this basis, he did so in disregard of the DME fix

definitions shown on the approach chart.

195 An FAA flight check of the VOR and DME transmitters conducted on August 7, 1997, determined

that the systems were functioning properly and within prescribed tolerances.
Analysis 145 Aircraft Accident Report

2.4.1.4 Summary of Captain’s Performance on the Approach

As the approach progressed without encountering the visual conditions the captain

had anticipated, the captain likely experienced increased stress because of his inadequate

preparation for the nonprecision approach, which made the approach increasingly

challenging.196 CVR and FDR data indicated that, shortly after the captain appeared to

become preoccupied with the status of the glideslope, he allowed the airplane to descend

prematurely below the required intermediate altitudes of the approach. Thus, the captain

may have failed to track the airplane’s position on the approach because he believed that

he would regain visual conditions, the airplane was receiving a valid glideslope signal,

and/or the airplane was closer to the airport than its actual position.

Regardless of the reason for failing to track the airplane’s position, the captain

conducted the approach without properly cross-referencing the positional fixes defined by

the VOR and DME with the airplane’s altitude. Therefore, the Safety Board concludes

that, as a result of his confusion and preoccupation with the status of the glideslope, failure

to properly cross-check the airplane’s position and altitude with the information on the

approach chart, and continuing expectation of a visual approach, the captain lost

awareness of flight 801’s position on the ILS localizer-only approach to runway 6L at

Guam International Airport and improperly descended below the intermediate approach

altitudes of 2,000 and 1,440 feet, which was causal to the accident.

2.4.2 Flight Crew Monitoring of the Approach

CVR evidence indicated that the flight crew seemed confused about, and did not

react to, a series of audible ground proximity warning system (GPWS) alerts during the

final approach. The first audible GPWS callout occurred about 0141:42, with the “one

thousand [feet]” altitude call. A second GPWS callout of “five hundred [feet]” occurred

about 0142:00 (when the airplane was descending through about 1,200 feet msl), to which

the flight engineer responded in astonishment, “eh?” However, FDR data indicated that no

change in the airplane’s descent profile followed, and the CVR indicated that the flight

engineer continued to complete the landing checklist. Similarly, no flight crew discussion

followed the GPWS callout of “minimums” about 0142:14, and the first officer dismissed

a GPWS “sink rate” alert 3 seconds later by stating “sink rate okay.” About 0142:19, the

flight engineer called “two hundred [feet],” followed immediately by the first officer

saying “let’s make a missed approach.” The flight engineer immediately responded “not in

sight,” followed by the first officer repeating “not in sight missed approach.” According to

the CVR, a rapid succession of GPWS altitude callouts down to 20 feet followed, as the

flight crew attempted to execute the missed approach. 

196 Human factors research has shown that a common decision-making error, especially in high stress and

workload situations, is for people to tend to ignore evidence that does not support an initial decision. Human

“operators tend to seek (and therefore find) information that confirms the chosen hypothesis and to avoid

information or tests whose outcome could disconfirm it,” which produces an “inertia which favors the

hypothesis initially formulated.” See Wickens, C. (1992). Engineering Psychology and Human

Performance, 2nd Edition. Columbus, Ohio: Charles E. Merrill.
Analysis 146 Aircraft Accident Report

The GPWS minimums callout occurred about 12 seconds before impact, when the

airplane was descending through about 840 feet msl. The first officer’s first statement

suggesting the execution of a missed approach occurred about 6 seconds before impact.

The captain initiated a missed approach and thrust began increasing about 4 seconds

before impact. However, no significant nose-up control column inputs were made until

just before initial impact. Analysis of FDR data indicated that, if a missed approach had

been initiated 12 seconds before impact (at the GPWS minimums callout), it is likely that

the airplane would have successfully cleared terrain by about 450 feet. Analysis of the

FDR data also indicated that, if an aggressive missed approach had been initiated

6 seconds before impact (when the first officer made the first missed approach challenge),

it is possible that the airplane might have cleared the terrain. 

The Safety Board notes that the flight crew would have been gauging the

airplane’s height above the MDA by referring to the airplane’s barometric altimeter

(which displays altitude above sea level) and not the radio altimeter (which senses altitude

above ground level and upon which the GPWS minimums callout was based) and that the

MDA of 560 feet msl was never reached. Nevertheless, the GPWS callouts were a salient

cue that should have caused the flight crew to question the airplane’s position and the

captain to act conservatively and choose to execute a missed approach. The Safety Board

concludes that the first officer and flight engineer noted the GPWS callouts and the first

officer properly called for a missed approach, but the captain’s failure to react properly to

the GPWS minimums callout and the direct challenge from the first officer precluded

action that might have prevented the accident.

Although the first officer properly called for a missed approach 6 seconds before

impact, he failed to challenge the errors made by the captain (as required by Korean Air

procedures)197 earlier in the approach, when the captain would have had more time to

respond. Significantly, the first officer did not challenge the captain’s premature descents

below 2,000 and 1,440 feet. 

The Safety Board was unable to identify whether the absence of challenges earlier

in the approach stemmed from the first officer’s and the flight engineer’s inadequate

preparation during the approach briefing to actively monitor the captain’s performance on

the localizer approach, their failure to identify the errors made by the captain (including

the possibility that they shared the same misconceptions as the captain about the

glideslope status/FD mode or the airplane’s proximity to the airport), and/or their

unwillingness to confront the captain about errors that they did perceive.

The Safety Board notes that the captain’s failure to brief the localizer approach to

back up the expected visual approach could have adversely affected the flight crew’s

197 Korean Air’s cockpit training procedures instructed the pilot flying a nonprecision approach (with the

autopilot engaged) to program the autopilot/FD controls, including VERT SPEED and ALT SEL (altitude

select), unless that pilot directed the nonflying pilot to do so. In addition, flight crews were trained that,

while executing the approach profile, the flying pilot was to initiate all heading, course, and altitude

changes, including selection of the step-down altitudes. The role of the nonflying pilot was to monitor and

challenge if the flying pilot failed to follow proper procedures.
Analysis 147 Aircraft Accident Report

preparation for monitoring the approach. If the captain had briefed the details of the

approach, including the various navigational fix definitions and associated altitude

constraints, he would have enhanced the flight crew’s ability to monitor the approach and

challenge any errors he made.

Even if the first officer was attempting to monitor the approach, his ability to

identify errors made by the captain would have been impaired by the requirement that he

tune his navigation receiver to the UNZ VOR, thus forcing him to look across the cockpit

to the captain’s instruments to monitor the glideslope/FD status, any indications of

glideslope capture on the captain’s ADI and HSI, and the airplane’s lateral position on the

localizer. However, the first officer would have had information on his own HSI and radio

magnetic indicator about the airplane’s position relative to the VOR (the step-down fix for

the descent to 560 feet) and the DME readings that defined the remaining fixes of the

approach.

The first officer’s ability to monitor the captain was also possibly hindered by the

likelihood that he was using a different instrument chart than the captain for the localizer

approach. The Safety Board found an out-of-date chart for this approach (dated

January 19, 1996) in the cockpit. On the basis of the captain’s comments on the CVR, it

appears that the captain was using the correct chart (dated August 2, 1996), which

included different definitions and names of DME fixes and different crossing altitudes

than the out-of-date chart. Thus, if the first officer was using the out-of-date chart, he

would have been hindered in monitoring the captain’s compliance with the altitude

constraints at the fixes. 

Although the precise reason(s) for the lack of monitoring by the flight crew could

not be determined, the Safety Board concludes that the first officer and flight engineer

failed to properly monitor and/or challenge the captain’s performance, which was causal

to the accident.

Problems associated with subordinate officers challenging a captain are well

known. For example, in its study of flight crew-involved major air carrier accidents in the

United States,198 the Safety Board found that more than 80 percent of the accidents studied

occurred when the captain was the flying pilot and the first officer was the nonflying pilot

(responsible for monitoring). Only 20 percent of the accidents occurred when the first

officer was flying and the captain was monitoring. This finding is consistent with

testimony at the Safety Board’s public hearing, indicating that CFIT accidents are more

likely to occur (on a worldwide basis) when the captain is the flying pilot. (See section 2.8

for a discussion of CFIT accidents and prevention strategies, including monitored

approaches.) The Board’s study found that the failure of first officers to challenge errors

(especially tactical decision errors) made by a flying captain was a frequent factor in

accidents involving such errors. In addition, the study noted that, while monitoring and

challenging a captain’s tactical decision error, “a first officer may have difficulty both in

deciding that the captain has made a faulty decision, and in choosing the correct time to

198 A Review of Flightcrew-Involved Major Accidents of U.S. Air Carriers, 1978 Through 1990,

pp. 47-49 and 55-59.
Analysis 148 Aircraft Accident Report

question the decision.” The study concluded that a first officer “may be concerned that a

challenge to a decision may be perceived as a direct challenge to the captain’s authority.” 

The Safety Board is concerned that the use of the nonflying pilot in a passive role,

while the flying pilot is responsible for the approach procedure, programming the

autopilot/FD controls, and monitoring the aircraft flightpath, places an inordinately high

work load on the flying pilot and undertasks the nonflying pilot. The Board is also

concerned that, when the nonflying pilot has a passive role in the approach, the flying pilot

may erroneously consider the lack of input from the nonflying pilot as confirmation that

approach procedures are being properly performed. The Board is aware that some

international air carriers use the nonflying pilot in a more interactive role during the

performance of a nonprecision approach, in which that pilot leads or prompts the flying

pilot through the approach procedure by stating the next procedural change, including

course, heading, altitude, time, visual contact, or MAP. The Board is also aware that some

air carriers employ a “monitored approach” method, with the first officer as the flying

pilot and the captain as the monitoring, nonflying pilot until just before landing.

The Safety Board notes that the monitored approach method provides for more

effective monitoring by the nonflying pilot because captains are more likely to be

comfortable offering corrections or challenges to first officers than the reverse situation.

Thus, the Safety Board concludes that monitored approaches decrease the workload of the

flying pilot and increase flight crew interaction, especially when experienced captains

monitor and prompt first officers during the execution of approaches. However, the Board

also notes that, when there are differences in aircraft handling skills between captains and

first officers and the approach is not flown using the autopilot, a monitored approach with

the captain as the nonflying pilot may not always be appropriate. Therefore, the Safety

Board believes that the FAA should conduct or sponsor research to determine the most

effective use of the monitored approach method and the maximum degree to which it can

be safely used and then require air carriers to modify their procedures accordingly.

2.4.3 Flight Crew Fatigue Factors

Fatigue can be a factor in flight operations.199 The Safety Board examined several

fatigue-related factors, including time of day, recent sleeping patterns, and the number of

hours since awakening, to determine whether fatigue was a factor in the accident captain’s

performance. The Board was unable to obtain information on the recent sleeping patterns

of the first officer and flight engineer. 

The accident occurred after midnight (about 0042) in the flight crew’s home time

zone (which is 1 hour behind Guam local time). Research has found that this time of day is

often associated with degraded alertness and performance and a higher probability of

errors and accidents.200 The arrival time was also several hours after the captain’s normal

199 Gander, P.H., Gregory, K.B., Miller, D.L., Graeber, R.C., Connell, L.J., and Rosekind, M.R. (1998).

“Flight Crew Fatigue V: Long-Haul Air Transport Operations.” Aviation, Space, and Environmental

Medicine, 69 (9, Section II, Supplement), pp. B37-B48.
Analysis 149 Aircraft Accident Report

bedtime (2200 to 2300 Seoul local time) and a time at which his body would have been

primed for sleep. 

CVR evidence indicated that the captain was tired. At the beginning of the

approach, the captain made unsolicited comments related to fatigue, stating

“eh...really...sleepy.” In its investigation of the 1993 American International Airways

accident at Guantanamo Bay, Cuba, the Safety Board noted that individuals often tend to

underestimate their own level of fatigue.201 Thus, the captain’s comment could have

reflected a significant performance degradation. Neither the first officer nor the flight

engineer made similar comments. 

According to his family, the captain slept his normal sleep routine in the days

before the accident and had an opportunity to receive adequate rest. He also took a nap

from 1100 to 1340 (Seoul local time) on August 5 and would therefore have been awake

for 11 hours at the time of the accident. The Safety Board has found this time since

awakening to be associated with greater errors.202 For example, in its investigation of the

1993 accident in Pine Bluff, Arkansas, the Board determined that the captain and first

officer had both been awake for 11 hours.203

Further, the sleep history provided by the captain’s family does not address the

quality of sleep he received. For example, the time of the captain’s reported nap

corresponds to a typical physiological period of wakefulness when napping is difficult204

and of limited efficiency at reducing sleep debt.205 If the captain actually napped at this

time, it suggests that he may have had unusual sleep needs that were not indicated by the

number of hours in his reported sleep history.206

200 Akerstedt, T. (1998). “Shift Work and Disturbed Sleep/Wakefulness.” Sleep Medicine Reviews, 2(2),

pp. 117-128.

201 National Transportation Safety Board. 1994. Uncontrolled Collision With Terrain, American

International Airways Flight 808, Douglas DC-8-61, N814CK, U.S. Naval Air Station, Guantanamo Bay,

Cuba, August 18, 1993. Aircraft Accident Report NTSB/AAR-94/04. Washington, DC, p. 135.

202 A Review of Flightcrew-Involved Major Accidents of U.S. Air Carriers, 1978 Through 1990,

pp. 23-28.

203 National Transportation Safety Board. 1994. In-flight Loss of Control, Leading to Forced Landing

and Runway Overrun, Continental Express, Inc., Embraer EMB-120RT, N24706, Pine Bluff, Arkansas,

April 29, 1993. Aircraft Accident Report NTSB/AAR-94/02/SUM. Washington, DC.

204 Dinges, D.F. “Napping Patterns and Effects in Human Adults.” In Sleep and alertness:

Chronobiological, behavioral, and medical aspects of napping. 1989. Ed. D.F. Dinges and R.J. Broughton.

New York: Raven Press, p. 181.

205 Lavie, P. “To Nap, Perchance To Sleep—Ultradian Aspects of Napping.” In Sleep and alertness:

Chronobiological, behavioral, and medical aspects of napping. 1989. Ed. D.F. Dinges and R.J. Broughton.

New York: Raven Press, pp. 114-117.

206 Investigation determined that, on July 27, 1997, the captain’s personal physician diagnosed him with

bronchitis and prescribed a medication that could be used as a sleeping aid. On July 28 through 30, the

captain flew an international round trip between Korea and the United States. The combined effects of the

captain’s illness and his long trip across numerous time zones were likely to have provided disruptions to his

sleeping schedule that might have continued to affect him at the time of the accident.
Analysis 150 Aircraft Accident Report

Fatigue degrades all aspects of performance and alertness, and deficiencies

associated with fatigue were displayed in many aspects of the captain’s behavior. The

captain’s preoccupation and confusion with the status of the glideslope to the exclusion of

other critical information, his incomplete briefing, and his failure to react to the GPWS

alerts are typical of fatigue effects that were found to be present in the Guantanamo Bay

and Pine Bluff accidents.

On the basis of the time of day, statements recorded on the CVR, and sleep and

fatigue research, the Safety Board concludes that the captain was fatigued, which

degraded his performance and contributed to his failure to properly execute the approach.

2.5 Pilot Training

The Safety Board examined Korean Air’s Boeing 747 pilot training and

proficiency checking program to determine what effect, if any, it may have had on the

performance of the flight crew of flight 801. In training its pilots to fly the 747-200 and

-300 series airplanes, Korean Air conducted 10 4-hour simulator sessions in which pilots

were taught various maneuvers, emergencies, and scenarios, followed by a proficiency

check in which pilot performance of certain maneuvers was assessed. The profile for each

simulator training session outlined the specific airport, runway, weather, and airplane

malfunction to be expected and whether the flight would result in a landing or missed

approach. The training curriculum was not varied. Korean Air’s Director of Academic

Training testified at the Safety Board’s public hearing that, at the time of the accident, the

company’s practice was to follow simulator scenarios exactly as outlined in the training

curriculum and that instructors were not permitted to vary the scenarios. The director also

indicated that the proficiency checks used the same approaches that had been practiced in

the previous simulator training sessions.

Further, the only nonprecision approach practiced throughout the simulator

sessions that used DME information was the VOR/DME approach to runway 32 at Seoul’s

Kimpo Airport. However, the DME at that airport is located on the field, unlike at Guam.

No scenario was presented in which pilots were required to count down to and fly past the

DME and then count up to the MAP, which was required for the Guam approach.207

Further, according to the airline’s training syllabus, the VOR/DME approach to runway 32

at Kimpo was the only nonprecision approach that Korean Air flight crews were required

to perform on their check ride.

The Safety Board notes that proper training in the execution of nonprecision

approaches is essential to safe operations. The complexity of such approaches and the

207 During training, Korean Air pilots performed two different NDB approaches; each was performed

once, and neither incorporated DME. The pilots also performed the localizer approach to runway 14 at

Kimpo once and the VOR/DME approach to runway 32 at Kimpo five times. The localizer and VOR/DME

approaches used a DME that was colocated and frequency paired with approach navigational facilities

located on the airport. Thus, the pilots were exposed to four nonprecision approaches during their training,

and the VOR/DME approach to runway 32 at Kimpo was the only approach performed more than once.
Analysis 151 Aircraft Accident Report

absence of precise vertical guidance create more demands on pilot skills and cognitive

performance than precision approaches. An expert on CFIT accidents testified the

following at the Board’s public hearing:

Nonprecision approaches generally are much more complex than precision

approaches. For many pilots, they are less familiar. They are more error-prone.

They require [a] more comprehensive briefing. They need particularly careful and

accurate monitoring, and it is possible for complex step-down procedures for

steps to be missed or to be taken out of step. In other words, to get one step ahead

of the airplane could be fatal. Such approaches also need much more carefully

managed airplane crew and checklist management, and it is a characteristic of

many CFIT accidents that they occur when the crew is preoccupied or distracted

by other tasks. 

The Safety Board notes that the Air Line Pilots Association (ALPA), in its

submission regarding this accident, estimated that air transport pilots typically conduct

one to three nonprecision approaches a year and practice these approaches “just as

infrequently” in the simulator. In its investigation of the November 12, 1995, accident

involving American Airlines flight 1572, an MD-83 that crashed in East Granby,

Connecticut, while on final approach to Bradley International Airport in Windsor Locks,

Connecticut,208 the Board found that even relatively minor errors in the monitoring of the

execution of a nonprecision approach can lead to an accident.209

The Safety Board is concerned that the repeated presentation of a single

nonprecision approach scenario throughout simulator training (to the exclusion of all other

kinds of nonprecision approaches) provides insufficient training in nonprecision

approaches. Specifically, the repetition limits pilots’ opportunity to understand and

practice the flying techniques necessary to perform the different kinds of nonprecision

approaches and limits their ability to successfully apply these techniques to novel

situations or unusual approach configurations encountered in line operations, such as the

localizer approach at Guam. Further, Korean Air’s reliance on the same approach for both

training and checking resulted in an inadequate evaluation of a flight crew’s ability to

execute the varied nonprecision approaches that might be encountered in line

operations.210 Therefore, the Safety Board concludes that Korean Air’s training in the

208 National Transportation Safety Board. 1996. Collision With Trees on Final Approach, American

Airlines Flight 1572, McDonnell Douglas MD-83, N566AA, East Granby, Connecticut, November 12, 1995.

Aircraft Accident Report NTSB/AAR-96/05. Washington, DC. 

209 The Safety Board found similar nonprecision approach-related factors in its investigation of the 1995

accident involving an American Airlines Boeing 757 on a nonprecision approach to Cali, Colombia; the

1990 accident involving a Markair Boeing 737 on a nonprecision approach to Unalakleet, Alaska; the 1989

accident involving a Flying Tigers Boeing 747 that crashed while executing an NDB approach to Kuala

Lumpur, Malaysia; and the 1989 incident involving a USAir Boeing 737 executing a localizer backcourse

approach to Kansas City, Missouri.

210 The Safety Board notes the Korean Air simulator training now incorporates a variety of approach

scenarios, including approaches in which the DME is not colocated with an on-airport navigational facility

and approaches involving countdown/count up DME procedures. Also, the simulator training now includes

approaches likely to be encountered in the airline’s domestic and international operations. 
Analysis 152 Aircraft Accident Report

execution of nonprecision approaches was ineffective, which contributed to the deficient

performance of the flight crew. 

In addition, on the basis of the history of similar accidents involving U.S. air

carriers, the Safety Board concludes that U.S. air carrier pilots would benefit from

additional training and practice in nonprecision approaches during line operations (in

daytime visual conditions in which such a practice would not add a risk factor). Therefore,

the Safety Board believes that the FAA should issue guidance to air carriers to ensure that

pilots periodically perform nonprecision approaches during line operations in daytime

visual conditions in which such practice would not add a risk factor.

2.6 Air Traffic Control Factors

2.6.1 Controller Performance

Safety Board investigators evaluated the performance of the CERAP and Agana

tower controllers to determine whether their performance played a role in the

circumstances of the accident. FAA Order 7110.65, “Air Traffic Control,” prescribes the

ATC procedures that controllers are required to follow. The investigation revealed three

deviations from those procedures on the part of the CERAP controller.

The CERAP controller failed to provide the flight crew with a position advisory

relative to a fix on the final approach course when he cleared flight 801 for the approach.

If such a position advisory had been given, as required by paragraph 5-9-4, the pilots

might have been prompted to cross-check their radar position with the cockpit DME and

other navigational aid indications, thereby improving their situational awareness. In

addition, the CERAP controller did not inform the flight crew or the tower controller that

he had observed a rain shower (described by the CERAP controller as a “cell” during a

postaccident interview with Safety Board investigators) on the final approach path, as

required by paragraph 2-6-4. Although the pilots should have been aware of the weather

situation because they were using on-board weather radar, their decision-making might

have been aided if the CERAP controller had provided his weather observations. 

The CERAP controller also failed to monitor the flight after the frequency change

to the tower controller.211 As a result, the CERAP controller did not immediately

recognize that the airplane was overdue. (Paragraph 10-3-1 states that a controller who has

any reason to believe that an aircraft is overdue should immediately take appropriate

action.) If the CERAP controller had been properly monitoring the flight on one or both of

the radar displays he had available to him (the en route display and/or the terminal

display), he might have observed flight 801 disappear on final approach. Also, the

controller might have noticed the approach path warning (low-altitude MSAW alert) that

was generated on the en route radar display,212 which began about 6 seconds before impact

211 The controller was required to continue monitoring the flight because radar service had not been

terminated in accordance with paragraph 5-1-13.
Analysis 153 Aircraft Accident Report

and continued until at least 23 seconds afterward. These actions would have resulted in an

earlier notification of the accident to emergency rescue personnel and possibly an earlier

emergency response. (See section 2.7 for a discussion of the emergency response.)

Further, if the CERAP controller had been monitoring the flight on the terminal

radar display, which was located to his immediate right and would have been clearly

visible to him,213 he might have seen the airplane descend prematurely toward high terrain

and have been able to alert the flight crew and prevent the accident. This radar display

would have shown the flight descending through 2,000 feet msl while almost 7 miles from

the airport and outside of the outer marker. The radar display would have also shown the

airplane crossing the outer marker almost 800 feet lower than the established crossing

altitude of 2,000 feet.214

Although the CERAP controller told Safety Board investigators that he did not

continue to monitor the flight because he was engaged in other duties about the time of the

accident, the ATC transcripts indicated no activity during that time. The transcripts

indicated that the controller instructed the flight crew, about 0140:42, to contact the Agana

tower. The controller then made a radio transmission to another aircraft about 0140:54.

From about 0141:14 to 0141:30, the controller had a conversation with another controller

at a different center, and about 0142:05, he acknowledged a transmission from another

aircraft. However, the transcripts indicated no further activity until 0143:49, when the

CERAP controller called the Agana tower with a flight plan. Thus, the ATC transcripts

indicated no activity during the time period beginning 21 seconds before and continuing

until 1 minute 23 seconds after the flight 801 crash (which occurred about 0142:26).

Therefore, the CERAP controller should have been able to monitor the flight during this

time. If the controller had done so, he would have had an opportunity to warn the flight

crew of the flight’s premature descent and possibly prevent the accident.

The Safety Board concludes that the CERAP controller’s performance was

substandard in that he failed to provide the flight crew with a position advisory when he

cleared the flight for the approach, inform the flight crew or the Agana tower controller

that he had observed a rain shower on the final approach path, and monitor the flight after

the frequency change to the tower controller. It could not be determined whether the

212 The CERAP controller was monitoring the EARTS (en route) radar scope, which had a functioning

MSAW capability. However, this MSAW capability was based on a different algorithm than the disabled

ARTS IIA MSAW system (see section 2.6.2). The ARTS IIA MSAW system compares the airplane’s

trajectory with the ILS glideslope. The EARTS system uses a single altitude (based on the lowest MDA for

all nonprecision approaches to the runway) from the FAF to the point at which MSAW processing terminates

(usually 1 mile from the runway threshold). 

213 The Safety Board recognizes that the en route radar display was set to a range of 265 nm and therefore

could not be used for effectively monitoring the final approach. The terminal radar display was set to a range

of 60 nm and displayed the final approach course for runway 6L.

214 Although the CERAP controller told Safety Board investigators that his last observation of the target

of flight 801 on the terminal radar display was when the airplane was 7 miles from the airport at an altitude

of 2,600 feet, FDR and radar data do not support his statement. The data indicated that, when the CERAP

controller instructed the flight to contact the Agana tower, the airplane was at an altitude of about 2,200 feet

and maintained a continual descent. Therefore, the airplane was probably farther than 7 miles from the

airport when the CERAP controller last observed the flight.
Analysis 154 Aircraft Accident Report

absence of the CERAP controller’s procedural errors, singularly or in any combination,

would have prevented the accident or reduced its severity. However, the Safety Board

concludes that strict adherence to ATC procedures by the CERAP controller may have

prevented the accident or reduced its severity. Therefore, the Safety Board believes that

the FAA should develop a mandatory briefing item for all air traffic controllers and ATC

managers, describing the circumstances surrounding the performance of the CERAP

controller in this accident to reinforce the importance of following ATC procedures.

2.6.2 Intentional Inhibition of the Minimum Safe Altitude 

Warning System at Guam

Since February 1995, the Guam ARTS IIA MSAW system215 had been

intentionally inhibited by the FAA from providing low-altitude alerts inside a 54-nm ring

around the ASR-8 radar antenna. The system was inhibited because it had been generating

what air traffic controllers believed to be numerous false alerts, or “nuisance warnings.”

Thus, at the time of the accident, the MSAW system was only available (uninhibited) in a

1-mile-wide band around the ASR-8 radar site, between 54 and 55 nm. Korean Air flight

801 crashed approximately 3 nm southwest of Guam International Airport in an area of

rising terrain that would have been covered by the MSAW system if it had not been

inhibited.

FAA technical staff and Safety Board investigators conducted a postaccident

simulation using the original parameters intended for the system. The simulation results

indicated that, if the MSAW system had not been inhibited inside the 54-nm radius, both a

visual and aural low-altitude alert would have been generated on the ARTS IIA monitors

in the CERAP facility about 0141:22, as the airplane was descending through 1,700 feet

msl. Accordingly, the Safety Board concludes that, if the ARTS IIA MSAW system had

been operating as initially intended, a visual and aural warning would have activated about

64 seconds before flight 801 impacted terrain, and this warning would have likely alerted

the CERAP controller that the airplane was descending below the minimum safe altitude

for that portion of the approach. 

Flight 801 was under the control of the Agana tower controller at the time that the

low-altitude MSAW alert would have been issued by the ARTS II system in the CERAP

facility. The Agana tower was not equipped with a functioning terminal radar display.

Therefore, for the crew of flight 801 to have received a low-altitude advisory, the CERAP

controller (who was still responsible for monitoring the airplane after he initiated a

frequency change to the tower controller) would have had to relay the alert to the tower

controller, who would then have had to convey the alert to the flight crew. Given the

prevalence of CFIT accidents, controllers would be expected to vigilantly monitor the

system and provide timely notification to either another controller or a flight crew when

215 As previously stated, the purpose of the ground-based MSAW system is to provide air traffic

controllers with a visual and an aural warning whenever an airplane descends, or is predicted to descend,

below a prescribed minimum safe altitude. This information can then be relayed to the pilots so they can

take remedial action.
Analysis 155 Aircraft Accident Report

an MSAW alert indicates the existence of an unsafe situation. The Safety Board concludes

that 64 seconds would have been sufficient time for the CERAP controller to notify the

Agana tower controller of the low-altitude alert, the tower controller to convey the alert to

the crew of flight 801, and the crew to take appropriate action to avoid the accident.

Because of its periodic evaluations of air traffic facilities, FAA quality assurance

staff knew as early as July 1995 that the Guam ARTS IIA MSAW system had been

inhibited. The inhibition was cited in a 1995 FAA facility evaluation report but was only

classified as an “informational” item. The FAA conducted no followup activities after the

1995 evaluation to determine whether corrective action had been taken to restore the

MSAW system to the full service for which it was designed. In April 1997, the FAA

conducted a second evaluation of the Guam facility, but the FAA’s report on this

evaluation did not even note that the ARTS IIA MSAW system was inhibited. Thus, the

FAA missed two opportunities not only to recognize that the MSAW system was inhibited

to the extent that it was rendered almost completely useless but also to take corrective

action. An appropriate corrective action could have prevented this accident. Therefore, the

Safety Board concludes that the FAA’s quality assurance for the MSAW system was

inadequate, and the agency’s intentional inhibition of that system contributed to the flight

801 accident. 

As previously noted, in this accident there would have been sufficient time

(64 seconds), if the MSAW system had generated an alert in the CERAP facility, for the

CERAP controller to have relayed the information to the tower controller. However, under

different circumstances, an aircraft descending below the minimum safe altitude may not

generate an MSAW alert as far in advance, so controllers may have significantly less time

to react. In those cases, it would make a critical difference if the MSAW alert were

provided directly to the airport tower.

The Safety Board has long been concerned about the issue of aural MSAW alerts

in towers. As part of its investigation into the January 1995 Beechcraft A36 accident, the

Safety Board found that the FAA did not have a policy regarding the installation of an

aural MSAW alert at low-density ATC towers equipped with D-BRITE radar displays. As

a result, the Safety Board issued Safety Recommendation A-95-120 on November 30,

1995. Safety Recommendation A-95-120 asked the FAA to develop a policy that would

require the installation of aural MSAW equipment in those visual flight rules (VFR)

terminal facilities that receive radar information from a host radar control facility and

would otherwise receive only a visual MSAW alert.216

In June 1996, the FAA stated that it was feasible to install the aural MSAW alert in

112 VFR towers. In July 1997, the FAA stated that 69 of 112 ATC facilities did not have

remote displays with aural alarms and that aural alarms at these facilities would be

installed by February 1998. In May 1998, the FAA stated that the aural alarms at these

69 remote sites would be operational by the end of that month. However, in March 1998,

at the Safety Board’s public hearing, the FAA’s Deputy Program Director for Air Traffic

216 For more information on this safety recommendation, see section 1.18.2.2.
Analysis 156 Aircraft Accident Report

Operations indicated that the new projected completion date for the installation of aural

alarms in VFR towers was April 2000. In October 1998, the Safety Board expressed its

concern to the FAA that VFR tower controllers who have visual representation from a

distant host radar may not receive an aural alert when aircraft under their control, or with

whom they are in radio communication, descend below the minimum safe altitude. The

Board asked the FAA to ensure that all VFR tower controllers with visual representation

from a host radar would in fact receive such warning. Pending further information from

the FAA, Safety Recommendation A-95-120 was classified “Open—Acceptable

Response.”

On September 29, 1999, a representative from the FAA stated that the agency’s

management had indicated that the Agana tower was currently receiving aural MSAW

alerts. At an October 7, 1999, briefing attended by the FAA Administrator, the Safety

Board Chairman, and staff from both agencies, the FAA indicated that 69 MSAW aural

alarms had been delivered and that 51 alarms were to be delivered. The FAA expected that

the acquisition of these 51 alarms would be completed by October 2000 and that their

installation in VFR towers would be completed by April 2001.

On October 12, 1999, the FAA Program Director for Serco Aviation Services told

Safety Board staff that the Agana tower has the capability to receive an aural MSAW alert

but that, unless the Guam CERAP transfers responsibility for the aircraft’s data block, the

tower will not receive the warning. The official added that the CERAP does not currently

transfer responsibility for the aircraft’s data block to the Agana tower; therefore, the tower

does not receive an aural MSAW alert.

On October 14, 1999, the FAA Program Director for Air Traffic Operations

confirmed that Agana tower was not receiving aural MSAW alerts. In an October 15,

1999, facsimile, the program director indicated that the tower “has the software and

hardware capability in place to receive aural alarms.” The director further stated that the

FAA had issued a policy “to ensure that the facility that is in direct radio communications

with the aircraft receives the aural alarm” and that the policy would become effective by

November 15, 1999. In a followup telephone conversation with the Safety Board’s

Director of the Office of Aviation Safety, the program director indicated that a national

policy would be issued to ensure that procedures similar to those being implemented at

Guam are followed at other VFR towers. 

On October 25, 1999, the FAA indicated that the MSAW aural alarms for the

ARTS IIA system at Guam were reconfigured on October 24, 1999. The FAA stated that,

in the event of a low-altitude alert for an aircraft operating in the vicinity of Guam

International Airport, aural alarms will be simultaneously generated at the CERAP and the

Agana tower, along with visual low-altitude alerts on the radar displays at both facilities. 

On November 2, 1999, the Safety Board received a copy of draft FAA Notice

N7210.485, “Minimum Safe Altitude Warning for Remote Tower Displays.” According to

the notice, facility managers at ATC towers that have aural alarms for MSAW are to

ensure that “the operational support facility has adapted the software functionality to

ensure the aural alarms operate in the ATCT [air traffic control tower]” and that “aural
Analysis 157 Aircraft Accident Report

alarms are received in the ATCT upon transfer of communications.” The FAA indicated

that the effective date for this notice would be February 1, 2000. 

The Safety Board is concerned about the delay in the implementation of Safety

Recommendation A-95-120.217 In addition, the Safety Board is especially concerned that

the FAA, until it received queries from the Board, was apparently not aware of, or not

addressing, procedural barriers that prevented the installed equipment from being used as

intended. However, on the basis of the FAA’s apparent continued intention to fully

implement this recommendation, it remains classified “Open—Acceptable Response.”

2.7 Emergency Response

Although a fire station was located about 1 mile from the accident site, the first

emergency response equipment (dispatched from a different fire station about 3 1⁄2 miles

from the accident site) did not arrive on scene until approximately 52 minutes after the

accident. Safety Board investigators attempted to determine the reason(s) for the slow

emergency response and the extent to which it could have been reduced or avoided.

Because of the air traffic controllers’ delayed discovery of the accident, ramp

control personnel, who were responsible for emergency notifications, were not aware of

the accident until 0158, about 16 minutes after the crash occurred. As discussed in section

2.6.1, if the CERAP controller had been monitoring the flight more closely, this delay

might have been eliminated or reduced.

After being notified of the accident by Guam airport ramp control, the Guam Fire

Department (GFD) communications center dispatched GFD Engine No. 7, which was

stationed about 3 1⁄2 miles from the crash site, at 0207. However, Engine No. 7’s departure

from the station was delayed by 12 minutes because its brake system needed to be

recharged with air. Engine No. 7 departed the station at 0219, and its en route response

time was 15 minutes. Engine No. 7 was the first emergency response vehicle to arrive at

the VOR access road (at 0234, 52 minutes after the accident).

The nearest fire station to the accident site was the U.S. Navy Federal Fire

Department (located about 1 mile from the accident site). According to Federal dispatch

facility logs, that station was not notified of the accident until 0234. The station’s Engine

No. 5 was then immediately dispatched and arrived at the accident scene at 0239

(a response time of 5 minutes). The Chief of Staff for the Commander, U.S. Naval Forces,

Marianas, notified Navy "first responders" to stand by after she learned of the accident at

0216. However, the Navy had not yet received a request for specific Federal firefighting

and medical resources; therefore, it would have been inappropriate for the Chief of Staff to

have dispatched these resources.

217 The Safety Board is also disappointed that the aural MSAW alert could not be installed on the

D-BRITE system at Guam in a timely manner because the FAA did not certify the system until April 1998,

more than 1 year after it was delivered. 
Analysis 158 Aircraft Accident Report

The emergency response was further delayed because the VOR access road—a

partially paved, single-lane road that was the only ground access to the accident site—was

blocked by a section of severed pipe218 when emergency responders arrived. Emergency

responders had to walk to the crash site through steep, muddy terrain and dense vegetation

until 0334, when a truck-mounted winch removed the pipe. Fire and rescue personnel

stated that only small, isolated fires remained when they were finally able to reach the

accident scene with firefighting equipment. 

A U.S. Navy emergency medical technician assigned to the Naval Regional

Medical Center reached the accident site on foot between 0245 and 0300. He stated that

emergency responders established two triage areas to treat survivors. He added that

transport of the survivors to hospitals was delayed because of the terrain and limited

access to the crash site and the necessity to stabilize patients in triage. The first survivors

were transported to hospitals between about 0300 and 0330. Rescue personnel testified at

the Safety Board’s public hearing that the pace of evacuations increased after the pipe

blocking the access road was removed and a landing area for helicopters was set up near

the VOR. 

The Safety Board is concerned that the first emergency response equipment did not

arrive at the accident scene until about 52 minutes after the accident. Although the harsh

terrain and the broken pipeline could not have been controlled, the delay caused by air

traffic controllers’ initial unawareness of the accident, the need to recharge the brake

system on the GFD Engine No. 7, and the lack of timely notification to the Federal Fire

Department could have been avoided. Thus, the Safety Board concludes that a substantial

portion of the delayed emergency response was caused by preventable factors.

The autopsy reports indicated that at least one seriously injured passenger was

treated at the accident site. Although the autopsy report for this passenger did not identify

a single cause of death (her remains showed evidence of multiple internal injuries but no

burns or soot in the airways), the report indicated that she was alive when medical

personnel arrived, was treated aggressively, and might have survived if earlier medical

intervention and evacuation had occurred. Therefore, the Safety Board concludes that the

delayed emergency response hampered the timely evacuation of injured persons, and at

least one passenger who survived the initial impact and fire might not have died if

emergency medical responders had reached the accident site sooner.

According to public hearing testimony by Guam’s Civil Defense Director, at the

time of the accident, Guam emergency response authorities had a memorandum of

understanding (MOU) with the U.S. Air Force for emergency response but did not have

agreements with the U.S. Navy or U.S. Coast Guard. The director further stated that,

before the accident, a joint disaster drill had been conducted at the airport, but no drills

had been conducted for off-airport crash emergencies. At the public hearing, the Guam

Civil Defense Director and other Guam officials stated that a committee, including

representatives from Guam, the U.S. Navy, the U.S. Coast Guard, and the U.S. Air Force,

218 The airplane’s landing gear had struck an oil pipeline on the side of the road and pushed portions of

the pipeline into the road.
Analysis 159 Aircraft Accident Report

had been formed to develop an MOU; an off-airport aircraft accident drill was planned for

September 1998; and new radios had been purchased to allow interagency communication

and coordination during emergency responses. However, Guam Civil Defense officials

told the Safety Board in June 1999 that no MOU had been signed and that a draft of

standard operating procedures for joint emergency response was being circulated to

agencies for review. Further, Guam Civil Defense officials stated that the planned

September 1998 off-airport aircraft accident drill did not take place and that such an

exercise was still in the planning stage. 

Although it is pleased with the purchase of new emergency radios, the Safety

Board concludes that improved formal coordination among Guam’s emergency response

agencies has not been implemented, and off-airport drills to identify and correct

deficiencies in disaster response planning before an accident occurs have still not been

conducted in the more than 2 years since the flight 801 accident. Thus, the Safety Board

also concludes that actions taken by Guam’s emergency response agencies after the

accident have been inadequate because they failed to ensure that emergency notifications

and responses would be timely and coordinated. Therefore, the Safety Board believes that

the Governor of the Territory of Guam should form, within 90 days, a task force

comprising representatives from all emergency response agencies on the island, including

the appropriate departments within the government of Guam, FAA, Guam International

Airport Authority, U.S. Navy, U.S. Air Force, U.S. Coast Guard, Federal Emergency

Management Agency, and all other affected agencies, to define and coordinate emergency

notification and response procedures to ensure that timely emergency notifications are

made to all local and Federal agencies according to need, location, and response time

capability. Further, the Safety Board believes that the Governor of the Territory of Guam

should require periodic and regularly scheduled interagency disaster response exercises,

including an off-airport aircraft accident scenario, in addition to those response drills

already required at Guam International Airport in accordance with 14 CFR Section

139.325.

2.8 Controlled Flight Into Terrain

According to Flight Safety Foundation (FSF) accident data, CFIT accidents have

killed more passengers and crewmembers than any other type of air carrier accident, and

approach and landing accidents accounted for 70 percent of CFIT accidents, with most

accident airplanes “in line with the runway” at impact. CFIT accident data also indicated

that nonprecision approaches presented a greater risk than precision approaches and that

many CFIT accidents involved failed step-down approaches, with flight profiles similar to

that of flight 801’s approach to Guam. As noted in section 2.5, nonprecision approaches

are practiced infrequently by air carrier pilots and generally require more extensive

briefings and careful monitoring than a typical instrument approach. 

The FSF CFIT task force also identified several common factors found in CFIT

accidents, including night conditions, limited visibility, terrain not seen until just before

impact, a stabilized descent path approximating a 3° slope, loss of horizontal and/or
Analysis 160 Aircraft Accident Report

vertical situational awareness, unfamiliarity with terrain and obstructions, uncertainty

about altitudes and/or distance from the airport, navigational equipment improperly set, or

information misinterpreted. The Safety Board notes that many of these factors were

present in this accident.219

On October 16, 1996, the Safety Board issued Safety Recommendation A-96-95,

asking the FAA to develop a CFIT program that includes realistic simulator exercises

comparable to the successful windshear and rejected takeoff training programs and make

training in such programs mandatory for all pilots operating under 14 CFR Part 121. On

February 25, 1997, the FAA issued a change to AC 120-51B, “Crew Resource

Management,” recommending that crew resource management (CRM) training in lineoriented flight training or special purpose operational training modules contain a CFIT

scenario. However, the FAA did not require this CFIT training, as urged by the Safety

Board. Pending further correspondence from the FAA, Safety Recommendation A-96-95

was classified “Open—Acceptable Response” on November 13, 1997. 

A CFIT Education and Training Aid, which was developed under the auspices of

the FSF and made available to air carriers in 1997, provides an overall summary of CFIT

“traps,” outlines causal factors of CFIT accidents, and provides training guidance for

specific escape maneuvers. The education and training aid focuses on altimeter errors,

procedural errors, misuse of automation, terrain avoidance, and aggressive escape

maneuvers. The training materials include a video and a CFIT checklist designed to

evaluate mission-specific CFIT risk factors, such as nonprecision approaches, airports

near mountainous terrain, duty time, and weather factors. Thus, because CFIT is one of

the leading categories of air carrier accidents and this type of accident is likely to increase

as worldwide air traffic levels increase, the Safety Board concludes that CFIT accident

awareness and avoidance training is an important accident reduction strategy and should

be mandatory for all pilots operating under 14 CFR Part 121. 

The Safety Board is disappointed that the FAA has not yet mandated CFIT

training, despite its demonstrated value to air carrier flight crews and in the reduction of

CFIT accidents. On August 11, 1999, the FAA stated that it had initiated a notice of

proposed rulemaking (NPRM) to mandate CFIT training. The FAA indicated that the

NPRM would be published in December 2000. Because of the FAA’s planned rulemaking,

Safety Recommendation A-96-95 remains classified “Open—Acceptable Response.”

However, the Safety Board notes with concern that the FAA’s expected publishing date for

the NPRM (December 2000) would occur more than 4 years after the issuance of the

recommendation. Experience has shown that implementation of a final rule could take

several additional years. In light of the fact that the CFIT training program is already

available to the industry, this delay appears unnecessary and unreasonable. Therefore, the

Safety Board urges the FAA to expedite this rulemaking.

219 According to Korean Air’s Director of Academic Flight Training, the company’s CFIT awareness

training consisted of a discussion of GPWS alerts in ground school. The director stated that no CFIT

avoidance scenarios were included in the simulator training curriculum and that CFIT awareness materials

were collected in a “read file” that was available to flight crews. The director stated that Korean Air had no

formal CFIT training curriculum.
Analysis 161 Aircraft Accident Report

2.8.1 Constant Angle of Descent Nonprecision Approaches 

Some airlines have adopted a “constant angle of descent” technique for

nonprecision approaches. This technique involves descending on a constant descent angle

toward the runway and meeting all of the crossing restrictions of the nonprecision

approach procedure while avoiding intermediate level-offs. For this technique, the

crossing altitudes depicted on the approach chart are used only as the bottom portion of a

window through which the airplane passes as it descends. In most cases, the descent angle

is about 3°, except in instances in which terrain or obstructions require a steeper descent.

Because of terrain factors, some currently approved nonprecision approaches are not

amenable to being flown with a constant angle of descent method. 

One method for flying a constant angle of descent, in the absence of a groundbased glideslope signal, involves the use of on-board flight management system (FMS) or

GPS equipment that provides electronic guidance for a constant angle of descent. This

method uses the same flight instrument and FD displays as with an ILS approach. The

FMS or GPS equipment, one or both of which is widely installed in newer airplanes,

provides precise, real-time information about airplane position. 

Under FAA Order 8260.47, “Barometric Vertical Navigation Instrument

Procedures Development,” issued May 26, 1998, some airlines have received approval to

use preprogrammed FMS/GPS approaches that include three-dimensional navigation

guidance to the MAP, which is expressed as a barometric decision altitude. The

advantages of this method include greater precision, lower pilot workload, and the ability

to obtain FD guidance and couple the autopilot to fly the approach automatically. Pilots

are not required to use step-down fixes, which removes the chance for misinterpreting the

distance to the runway or the proper altitude for that distance and provides for a stabilized

approach throughout the descent. The Safety Board concludes that, by providing vertical

guidance along a constant descent gradient to the runway, the use of on-board FMSand/or GPS-based equipment can provide most of the safety advantages of a precision

approach during a nonprecision approach. Therefore, the Safety Board believes that the

FAA should require that all air carrier airplanes that have been equipped with on-board

navigational systems capable of providing vertical flightpath guidance make use of these

systems for flying nonprecision approaches whenever terrain factors allow a constant

angle of descent with a safe gradient.

The Safety Board notes that it is likely that most air carrier airplanes will be

equipped with on-board FMS and/or GPS equipment over the next several years and that

the lack of such equipment may ultimately result in the loss of approach capability to

certain runways for those airplanes not so equipped. Further, the Board acknowledges that

terrain along the approach courses to some runways may preclude a constant angle of

descent with a safe gradient, thus resulting in the loss of approach capability to certain

runways. However, on the basis of the safety advantages of the constant angle of descent

with vertical guidance versus step-down approaches, as demonstrated in the circumstances

of this accident, the Safety Board believes that the FAA should require, within 10 years,
Analysis 162 Aircraft Accident Report

that all nonprecision approaches approved for air carrier use incorporate a constant angle

of descent with vertical guidance from on-board navigation systems.

For those airplanes not yet equipped with on-board navigational systems capable

of providing vertical flightpath guidance, an alternative method allows pilots to

approximate a constant angle of descent. This method requires using a published approach

procedure that incorporates a defined point along the final approach course to begin a

constant angle descent to the runway of about 3°; this descent point and descent angle also

fulfill the minimum crossing altitudes at each step-down fix of the nonprecision approach.

If pilots are provided a tabular means of cross-referencing the distance from the runway

(measured by DME) and the proper altitude for that distance, they can adjust the airplane’s

rate of descent to approximate a constant angle. The advantages of this method include

greater awareness of the airplane’s position on the approach path and a more stabilized

approach, but there is additional workload involved in the cross-referencing of altitude

and distance.

In Safety Recommendation A-96-128, issued on November 13, 1996, the Safety

Board asked the FAA for the incorporation of constant angle descents instead of stepdown criteria. The FAA indicated that it has made progress in providing some of the

information pilots need to approximate a constant angle of descent (descent angles and

gradients to the runway from a defined starting point). However, the FAA continues to

provide insufficient information on approach charts to cross-reference DME distances and

altitudes. 

Thus, the Safety Board concludes that the safety of executing a nonprecision

approach using the constant angle of descent, or stabilized descent technique, would be

enhanced by adding to approach charts the cross-referenced altitudes versus distance from

the airport. Therefore, the Safety Board believes that the FAA should include, in

nonprecision approach procedures, tabular information that allows pilots to fly a constant

angle of descent by cross-referencing the distance from the airport and the barometric

altitude.

2.8.2 Safety Aspects of Enhanced Ground Proximity Warning 

Systems

At the time of the flight 801 accident, no Korean Air airplanes were equipped with

enhanced GPWS nor were they required to be so equipped. Further, enhanced GPWS was

not available for the 747-300 at the time of the accident. 

The Safety Board notes that postaccident enhanced GPWS simulations conducted

by AlliedSignal indicated that, if flight 801 had been equipped with enhanced GPWS, an

aural “CAUTION TERRAIN” warning and a yellow visual terrain depiction on the color

weather radar display would have been issued about 60 seconds before impact. An aural

“TERRAIN TERRAIN” and “PULL UP” warning and a red visual terrain depiction on the

weather radar scope would have been issued about 45 seconds before impact and would

have sounded continuously until completion of a successful escape maneuver or impact.
Analysis 163 Aircraft Accident Report

Safety Recommendation A-96-101, issued on October 16, 1996, asked the FAA to

examine the effectiveness of enhanced GPWS equipment and, if found effective, require

all transport-category aircraft to be equipped with an enhanced GPWS that provides pilots

with an early warning of terrain. In a May 4, 1999, letter to the Safety Board, the FAA

stated that it issued an NPRM in August 1998 to require terrain awareness and warning

system (TAWS) equipment (the name used in the NPRM for enhanced GPWS) on all civil

turbine-powered aircraft with six or more passenger seats within 4 years of the issuance of

a final rule. Pending the Board’s evaluation of the FAA’s completed action, Safety

Recommendation A-96-101 was classified “Open—Acceptable Response” on July 13,

1999. 

However, on May 12, 1999, the Safety Board expressed concern that the 4-year

installation time frame was too long for retrofitting enhanced GPWS to existing turbinepowered airplanes that currently lack any GPWS protection. As a result, the Board issued

Safety Recommendation A-99-36, urging the FAA to shorten the proposed installation

period for these airplanes to 3 years (with a completion deadline of May 2002).220

In a July 26, 1999, response to the Safety Board, the FAA indicated that it was

“committed to installing and using TAWS as expeditiously as possible.” The FAA stated

that the final rule would require installation of TAWS within 1 year after the effective date

on new-production airplanes and within 4 years for existing airplanes. The FAA added

that the installation timetable was based on “product availability” and the “manufacturing

approval process.” 

The Safety Board notes that, on August 16, 1999, the FAA issued a technical

standard order for TAWS equipment (specifications and installation requirements) and

that the proposed final rule for TAWS installation was scheduled to be issued by March

2000. The Board acknowledges the FAA’s progress to date on TAWS issues but notes with

disappointment that the 2005 installation deadline is 3 years longer than urged in Safety

Recommendation A-99-36 for existing airplanes that are not currently required to have a

GPWS. The Board continues to urge that the installation of enhanced GPWS be expedited

not only for those airplanes covered by Safety Recommendation A-99-36 but also for the

transport-category airplanes covered by Safety Recommendation A-96-101. Pending

further action by the FAA, the Safety Board classifies Safety Recommendations A-96-101

and A-99-36 “Open—Acceptable Response.”

2.8.3 Terrain Depiction on Approach Charts

Approach chart vendors use various methods of depicting obstructions and high

terrain on approach charts. On the plan view,221 some vendors use contour lines and color

220 Safety Recommendation A-99-36 superceded A-95-35, which had asked the FAA to require all

“turbojet-powered airplanes” with six or more passenger seats to be equipped with a GPWS. Safety

Recommendation A-99-36 asked the FAA to require that all “turbine-powered” airplanes with six or more

passenger seats not currently required to be equipped with GPWS to have an operating enhanced GPWS

installed within 3 years.

221 The plan view shows the approach viewed from above.
Analysis 164 Aircraft Accident Report

shading for various height gradients and symbols for high obstructions, and others use

broader colored areas with the minimum sector altitude for obstacle clearance printed over

each area. However, no chart vendor depicts terrain or obstructions on the profile view,222

which depicts the inbound approach course descent profile from an initial approach fix to

a landing or missed approach. Other than the depiction of certain obstruction heights,

there is no FAA requirement or standardized format to depict terrain on approach charts.

The Safety Board notes that Nimitz Hill was not depicted on the Guam runway 6L ILS

approach chart.

During an instrument approach, pilots generally refer to the plan view until they

are established on the inbound approach course, usually on the intermediate and final

approach segments. Once on the inbound approach course, pilots generally shift their

attention on the approach chart from the plan to the profile view. Thus, the Safety Board

concludes that terrain depiction on the profile view of approach charts could result in

increased flight crew awareness of significant terrain on the approach path. The Board

recognizes that logistical problems may be associated with obtaining and including this

information and that not all users agree that obstacle depiction on the profile view is

necessary and helpful. (See section 1.18.4.2.) Nevertheless, the Safety Board believes that

the FAA should evaluate the benefits of depicting terrain and other obstacles along a

specific approach path on the profile view of approach charts and require such depiction if

the evaluation demonstrates the benefits.

2.8.4 User Review of Instrument Procedures

Charting companies that publish instrument procedures receive the pertinent

information from the FAA on its Form 8260. This form includes data for the terminal area

as well as final approach and missed approach standards for a specific instrument

procedure. The manager of the FAA’s Western Flight Procedures Development Branch

testified at the Safety Board’s public hearing that, when an approach procedure is

completed but before it is published, the procedure is distributed to industry user groups,

including ALPA, the Air Transport Association, the Aircraft Owners and Pilots

Association, and airport operators, for review. The manager stated that the purpose of this

user review is to ensure that the final product is safe, accurate, and intelligible. The Safety

Board agrees with and endorses this practice. However, the Board notes that the FAA does

not provide user groups with the approach procedure in its final, graphical form as it will

be published and used. Rather, user groups are only given FAA Form 8260, which

describes the approach in words and numbers.

Industry user groups, including ALPA (according to its submission to the Safety

Board regarding this accident), have stated that the format of FAA Form 8260 makes it

difficult for them to evaluate the procedure. Thus, the Safety Board concludes that

valuable user group reviews of proposed new instrument procedures are hampered by the

format in which the information is disseminated; thus, user groups may not be able to

effectively evaluate whether a procedure is safe, accurate, and intelligible. Therefore, the

222 The profile view shows the approach viewed from the side.
Analysis 165 Aircraft Accident Report

Safety Board believes that the FAA should provide user groups, along with Form 8260,

draft plan and profile views of instrument procedures to assist the groups in effectively

evaluating proposed new procedures.

2.9 Oversight Issues

2.9.1 Korean Air

As discussed in sections 1.17.2.3 and 1.17.5.1, Korean Air established a CRM

program and undertook several other safety initiatives in response to previous accidents.

The company also had supervisor briefing and airport familiarization programs, both of

which exceeded Korean regulatory requirements. (For more information about these

programs, see section 1.17.3.)

The Safety Board recognizes that these efforts indicated a positive approach to

safety. However, the supervisor briefing, which could have assisted the flight crew in

preparing for the approach, did not review important items, such as NOTAMs or the

currency of approach charts. Also, the airport familiarization video did not adequately

prepare the crew for the possibility of a nonprecision approach in IMC, nor did it note that

the DME was not colocated with the localizer. Further, as discussed previously, some of

Korean Air’s training and operational procedures, such as the limited number and variety

of approach scenarios, lack of an interactive role for the nonflying pilot, and lack of

documented cockpit approach procedures that clearly defined crewmember duties,

contributed to the flight crew’s deficiencies in this accident.

Korean Air experienced a series of accidents (beginning before and continuing

after the Guam accident) involving crew coordination and performance (see section

1.17.5). These accidents raise broader questions about the adequacy of the company’s

training and operational procedures. The airline did take action in response to some of

these accidents to address the safety problems brought to light. However, the continued

occurrence of crew error accidents called for a broad in-depth assessment of the airline’s

flight operations to determine how best to mitigate opportunities for such errors.

At the Safety Board’s public hearing, the Korean Air Deputy Director of Flight

Operations appeared to recognize that, before the accident at Guam, Korean Air had not

been placing sufficient emphasis on flight safety and particularly on pilot training. He

testified:

Looking back upon this accident we feel that most of our management up to now

has been [ ] perhaps too short-term, short-[sighted], and superficial in its nature.

...from this point on for the purpose of ascertaining safe flight operations we plan

to make long-term plans and spare no resources in [attaining] this final objective

of flight safety. Accordingly, we will adjust our management systems and invest

all the more heavily into training and program development.223
Analysis 166 Aircraft Accident Report

The Safety Board acknowledges that, since the Guam accident, Korean Air has

taken significant management, operational, and flight crew training actions.224 However,

in light of the specific deficiencies that were discovered during the investigation of this

accident and Korean Air’s accident and incident history, the Safety Board concludes that,

at the time of the flight 801 accident, there were underlying systemic problems within

Korean Air’s operations and pilot training programs that indicated the need for a broad

safety assessment of these programs.

2.9.2 Korean Civil Aviation Bureau Oversight of Korean Air 

The KCAB is charged with oversight of the Korean civil airlines. At the time of

the accident, two KCAB operations inspectors were assigned to provide oversight of

Korean Air’s flight operations. Korean Air pilots who were designated by the KCAB as

check airmen and examiners conducted flight instruction, check rides, and proficiency

checks and issued type ratings. The KCAB inspectors provided an annual evaluation of

the flight skills of the check airmen and examiners but did not observe proficiency checks

or check rides on Korean Air’s wide-body fleet.225

According to its director, the KCAB routinely conducts one annual safety

inspection, four quarterly inspections, and an average of 40 random inspections of the

airline each year. The director added that the two safety inspectors assigned to Korean Air

at the time of the accident also had oversight duties at another Korean carrier.226

Regardless of the number of inspections of Korean Air performed by the KCAB, its

failure to identify and monitor trends within the airline that might be indicative of safety

problems raises questions about the adequacy of KCAB’s oversight of Korean Air.

Further, KCAB officials acknowledged that the agency, because of personnel workload

constraints, frequently relied on Korean Air to self-report corrective actions taken in

response to KCAB inspections and did not confirm directly that identified problems had

been addressed by the airline.

As previously noted, the syllabus for Korean Air’s KCAB-approved simulator

training program described the scenarios used in training, type ratings, and proficiency

checks, and these scenarios were followed repetitively, without deviation, during training

223 Korean Air officials subsequently asked that this statement be removed from the public record and

disagreed that there were deficiencies in Korean Air’s management approach. However, the statement may

well have been an adequate assessment of the company’s shortcomings, and the Safety Board is

disappointed that Korean Air officials apparently failed to recognize this possibility.

224 As discussed in sections 1.17.1 and 1.17.2.4, Korean Air contracted for extensive flight crew training

services (including courses on decision-making, communications skills, and CRM), revised simulator

curricula to include a variety of situations encountered during flight operations, increased the minimum

flight hour and experience qualification requirements for captains (from 3,000 hours and 3 years to

4,000 hours and 5 years), began a worldwide pilot recruitment program, and set a goal of installing enhanced

GPWS equipment on all Korean Air airplanes by the end of 2003.

225 According to the KCAB, its inspectors did observe proficiency checks and check rides on Korean

Air’s narrow-body fleet (including the MD-80 and the F.100).

226 According to the KCAB’s director, the agency was authorized after the accident to hire nine

additional employees, including five new inspectors, to bolster oversight activities. 
Analysis 167 Aircraft Accident Report

exercises. Further, the training and checking scenarios incorporated an inadequate number

and variety of nonprecision approach procedures. As a result of the airline’s rigid

adherence to a curriculum that provided an inadequate variety of approaches, flight crews

were inadequately prepared to conduct nonprecision approaches. Also, cockpit approach

procedures (for example, for the flying and nonflying pilot roles) were taught anecdotally

and were not documented. After the accident and discussions with Safety Board

investigators, the KCAB asked Korean Air to modify its simulator training syllabus to

include a diversity of approach scenarios and improve its CRM program. Korean Air

stated that it complied with these requests.

Implementing and maintaining the highest levels of aviation safety requires an

ongoing relationship between the regulator (in this case, the KCAB) and the airline (in this

case, Korean Air). Each entity plays an essential role: one complies with standards of

safety, and the other ensures that such compliance is maintained. One researcher described

the role of the regulator as follows:227

Regulators are uniquely placed to function as one of the most effective defen[s]es

against organizational accidents. They are located close to the boundaries of the

regulated system, but they are not of it. This grants them the perspective to

identify unsatisfactory practices and poor equipment that the organization has

grown accustomed to or works around.

The Safety Board acknowledges that, in October 1998, after several accidents and

incidents following the crash of flight 801, the Korean Ministry of Construction and

Transportation (of which the KCAB is a part) ordered a 6-month suspension of 138 flights

on 10 of Korean Air’s domestic routes and ordered it to reduce service on the Seoul-toTokyo route. The Safety Board further acknowledges that KCAB operations inspectors

now assigned to Korean Air have type ratings in the airplanes that the airline operates.

However, as discussed previously, at the time of the flight 801 accident, there were signs

suggesting underlying systemic problems within Korean Air’s operations and pilot

training programs that indicated the need for a broad safety assessment of these programs.

No such assessment was carried out by Korean Air or the KCAB before the accident.

Thus, the Safety Board concludes that the KCAB was ineffective in its oversight of

Korean Air’s operations and pilot training programs.

2.9.3 Federal Aviation Administration Oversight of Korean Air 

and Assessment of Korean Civil Aviation Bureau

The FAA issues operations specifications to foreign air carriers operating into the

United States pursuant to 14 CFR Part 129. The FAA also assigns a POI228 to each foreign

air carrier to provide oversight to that carrier. The POI for Korean Air at the time of the

227 Reason, J.T. (1997). Managing the risks of organizational accidents. Aldershot: Hampshire, England,

p. 182.

228 The FAA’s position title for POIs assigned to foreign carriers is International Geographic Inspector

(Operations).
Analysis 168 Aircraft Accident Report

accident stated that oversight of foreign carriers under Part 129 included inspections of

trip records and facilities in the United States and ramp inspections of airplanes and crews

when they were in the United States or its territories. However, the POI stated that the

FAA did not inspect, approve, or oversee a foreign airline’s training program or any of its

manuals or accomplish line checks or en route inspections on board foreign airlines.

(There is no requirement that a foreign carrier provide the FAA POI with flight operations

or training manuals.) The POI also stated that there was no formal interaction between the

KCAB and the FAA regarding their respective oversight activities relating to Korean Air.

The Safety Board notes that the purpose of the FAA’s International Aviation Safety

Assessment (IASA) program is to ensure that foreign air carriers operating in the United

States are receiving adequate oversight by their respective civil aviation authority (CAA).

The FAA developed this program in response to an identified need to oversee foreign

carriers operating to the United States; however, the FAA’s assessment under that program

is limited to an evaluation of the foreign CAA’s ability to provide oversight in accordance

with ICAO Annex 6 standards. The FAA does not directly assess whether foreign carriers

are receiving such oversight or are complying with Annex 6. When the FAA assessed the

KCAB in 1996, the FAA concluded that the KCAB was capable of overseeing Korean air

carriers in accordance with ICAO safety standards, and Korea was therefore given a

Category I rating (the highest rating of the three IASA categories). The FAA indicated that

it would reassess a country that has air carriers operating into the United States if there

was any reason to question whether that country was meeting its international safety

oversight obligations.

The substantial number of Korean Air crew-related accidents and incidents, the

deficiencies in Korean Air’s pilot training program, and the lack of documented cockpit

procedures suggest that Korean Air had not fully complied with the intent of paragraph

9.3.1 of ICAO Annex 6, which states that operators “shall establish and maintain a ground

and flight training program...which ensures that all flight crew members are adequately

trained to perform their assigned duties. [The training program] shall also include training

in knowledge and skills related to human performance and limitations...[and] shall ensure

that all flight crew members know the functions for which they are responsible and the

relation of those functions to the functions of other crew members.”

The reliability of the FAA’s assessment and rating of a country’s CAA under the

IASA program is becoming ever more important in light of increases in code-sharing and

other alliances involving U.S. and foreign carriers. U.S. carriers are likely to view a

positive assessment by the FAA and the resulting Category I rating as an indication that

the country’s airlines are receiving adequate oversight and are therefore maintaining an

adequate level of safety. However, even though Korea had received and maintained a

Category I rating, the evidence developed in this investigation (including that only two

operations inspectors were assigned to Korean Air and that neither was type rated for the

747, as well as the deficiencies in the KCAB’s oversight of Korean Air) and Korean Air’s

accident and incident record (both before and after the flight 801 crash) suggest that the

FAA’s IASA program was not adequate in its scope and depth to determine the capacity of

the KCAB to fully assess Korean Air’s level of safety or ensure that Korean Air was
Analysis 169 Aircraft Accident Report

receiving adequate oversight. The Department of Transportation Office of Inspector

General’s (DOT/IG) audit report, titled Aviation Safety Under International Code Share

Agreements, reached a similar conclusion. The DOT/IG report noted that the FAA’s

assessment under the IASA program “is quite different from a judgment about the safety

practices of an individual carrier.” The report further noted that the “FAA is itself a civil

aviation authority that meets international standards, but that is materially different from a

conclusion that all U.S. carriers therefore follow sound safety practices.”

The Safety Board concludes that the FAA’s IASA program (which evaluates a

foreign CAA’s ability to provide adequate oversight for its air carriers) is not adequate to

determine whether foreign air carriers operating into the United States are maintaining an

adequate level of safety. The Board notes that the DOT/IG’s audit report recommended

that U.S. carriers perform safety assessments of foreign carriers as a condition of approval

to enter into code share agreements and that the FAA should consider the results of those

assessments when performing IASA reviews. Further, the Safety Board believes that the

FAA should consider the accident and incident history of foreign air carriers as a factor

when evaluating the adequacy of a foreign CAA’s oversight and whether a reassessment

may be warranted.

2.9.3.1 Independent Accident Investigation Authority

The entity responsible for investigating aviation accidents and incidents in Korea

is an office within the KCAB known as the Aviation Safety Division. Thus, Korea has no

independent accident investigation authority. Experience has shown that an accident

investigation authority that is not independent of the regulatory authority may not be as

objective as necessary to identify and recommend changes. A proper accident

investigation requires a review of the practices and procedures of the responsible

regulatory agency and their possible role in the accident. Because the results of such an

assessment may necessitate conclusions and recommendations that are critical of, or

adverse to, the regulatory agency or its officials, many countries have concluded that no

accident investigation entity could fully perform such a function unless it was separate and

independent from the regulatory agency. 

Annex 13 to the Convention on International Civil Aviation (paragraph 5.4) states

that “the accident investigation authority shall have independence in the conduct of the

investigation and have unrestricted authority over its conduct.” On November 21, 1994,

the Council of the European Union (EU) adopted a directive that specifies that EU

Member States shall ensure, by November 21, 1996, that aviation accident and serious

incident investigations are conducted or supervised by a permanent body or entity that is

functionally independent of the national aviation authorities responsible for regulation and

oversight of the aviation system. All EU members have complied with, or are in the

process of complying with, the intent of this directive.229 The Safety Board concludes that

an independent accident investigation authority, charged with making objective

conclusions and recommendations, is a benefit to transportation safety.
Analysis 170 Aircraft Accident Report

2.10 Flight Data Recorder Documentation

The Safety Board was unable to validate data from 11 retrofitted sensors on the

accident airplane’s FDR because Korean Air lacked complete and accurate documentation

information for them. Although the data from the retrofitted sensors were not critical in

the investigation of this accident, the data might have been important under other accident

circumstances. For FDR data to be useful during an accident investigation, accurate

documentation that is readily available to investigators after an accident is needed.

After taking delivery of an airplane from a manufacturer, many airlines provide

additional data to be recorded on the FDR by retrofitting the airplane with additional

sensors or recording additional data from a flight data acquisition unit. Such retrofits are

often mandated by the governing CAA. In addition to the flight 801 accident, the Safety

Board has investigated several other recent accidents in which airlines were unable to

provide accurate and complete information from a retrofitted FDR because the airlines

were unable to provide FDR documentation necessary for a complete and thorough

readout.230 Thus, the Safety Board often lacked critical data for a reconstruction of the

airplane’s motion and the flight crew’s performance, which prolonged some

investigations.

The Safety Board has long been concerned about inadequate FDR documentation.

Since the early 1970s, the Board has made recommendations to improve FDR data

verification and documentation. In 1991, concerns about the airworthiness of FDRs

resulted in two safety recommendations to the FAA (A-91-23 and -24) aimed at

developing a permanent policy for FDR maintenance and record-keeping. Safety

Recommendation A-97-30 asked the FAA to publish, by January 1998, a promised AC

addressing the installation and maintenance of FDRs.

On October 5, 1999, the FAA issued AC 20-141, “Airworthiness and Operational

Approval of Digital Flight Data Recorder Systems.” The purpose of the AC is to provide

“guidance on design, installation, and continued airworthiness of Digital Flight Data

Recorder Systems.” Appendix 1 to the AC, “Standard Data Format for Digital Flight Data

Recorder Data Stream Format and Correlation Documentation,” provides “a standard for

the data stream format and correlation documentation that operators must maintain to aid

accident investigators in interpreting recorded flight data.” The appendix details how to

develop a document for each airplane that would provide the detailed information needed

by Safety Board investigators to transcribe each parameter recorded by an FDR. 

229 The FAA does not assess a country’s compliance with any of the provisions of Annex 13, which

addresses accident and incident investigation standards and practices. However, the Safety Board notes that,

during the Accident Investigation Group (AIG) divisional meeting held by ICAO from September 14 to 24,

1999, AIG delegates adopted a recommendation for the ICAO Council to take steps to expand the ICAO

safety oversight audit program to include an assessment of a country’s compliance with Annex 13. (The

program currently assesses a country’s compliance with Annexes 1, 6, and 8.)

230 See section 1.18.7.1 for a listing of these accidents.
Analysis 171 Aircraft Accident Report

The Safety Board is concerned that AC 20-141 was not finalized until more than

8 years after the issuance of Safety Recommendations A-91-23 and -24. Nonetheless, the

Board is pleased that the AC is now final and that it will provide airlines with critical and

necessary guidance to properly document FDR parameters and systems. As a result,

information from FDRs will be provided in the format needed by the Board for a complete

and accurate readout. 

In addition to AC 20-141, ICAO Annex 6, Part I, “International Commercial Air

Transport—Aeroplanes,” includes Attachment D, Flight Recorders. Section 3 of the

attachment, entitled “Inspections of flight data and cockpit voice recorder systems,”

provides guidance to Member States on the continued airworthiness of FDR systems, such

as details on how to conduct annual checks of every FDR parameter, including recorded

signal and transcribed engineering units. Paragraph 3.2.c states that “a complete flight

from the FDR should be examined in engineering units to evaluate the validity of all

recorded parameters.” In addition, paragraph 3.2.d states “the readout facility should have

the necessary software to accurately convert the recorded values to engineering units and

to determine the status of discrete signals.” If Korean Air had been following this ICAO

guidance and performing annual checks on all of the FDR parameters for the accident

airplane, the airline would have been able to determine the conversion equations necessary

to complete an FDR readout or would have been able to discover and correct the FDR

parameter documentation discrepancies. 

As the number of international flights increases, the possibility of accidents

involving foreign aircraft within the United States also increases. The Safety Board

concludes that it is critical that thorough documentation of the information recorded by an

FDR be available for foreign- or U.S.-registered air transport airplanes that fly into or out

of the United States. In accordance with the interagency group on international aviation

protocol, the Board will introduce AC 20-141 at the next ICAO flight recorder panel

meeting, with a proposal that the AC be adopted as the international standard and

recommended practice for FDR systems.
172 Aircraft Accident Report

3. Conclusions

3.1 Findings

1. After the flight crew made an initial sighting of Guam, Korean Air flight 801

encountered instrument meteorological conditions as the flight continued on its

approach to Guam International Airport.

2. Although flight 801 likely exited a heavy rain shower shortly before the accident, the

flight crew was still not able to see the airport because of the presence of another rain

shower located between Nimitz Hill and the airport.

3. By not fully briefing the instrument approach, the captain missed an opportunity to

prepare himself, the first officer, and the flight engineer for the relatively complex

localizer-only approach and failed to provide the first officer and flight engineer with

adequate guidance about monitoring the approach; therefore, the captain’s approach

briefing was inadequate.

4. The captain’s expectation of a visual approach was a factor in his incomplete briefing

of the localizer approach.

5. For flights conducted at night or when there is any possibility that instrument

meteorological conditions may be encountered, the failure to fully brief an available

backup instrument approach compromises safety.

6. The Korean Air airport familiarization video for Guam, by emphasizing the visual

aspects of the approach, fostered the expectation by company flight crews of a visual

approach and, by not emphasizing the terrain hazards and offset DME factors, did not

adequately prepare flight crews for the range of potential challenges associated with

operations into Guam.

7. The challenges associated with operations to Guam International Airport support its

immediate consideration as a special airport requiring special pilot qualifications.

8. Although the captain apparently became confused about the glideslope’s status, the

flight crew had sufficient information to be aware that the glideslope was unusable for

vertical guidance and should have ignored any glideslope indications while executing

the nonprecision localizer-only approach.

9. Navigation receivers, including glideslope receivers, may be susceptible to spurious

radio signals.
Conclusions 173 Aircraft Accident Report

10. The captain may have mistakenly believed that the airplane was closer to the airport

than its actual position; however, if the captain conducted the flight’s descent on this

basis, he did so in disregard of the DME fix definitions shown on the approach chart.

11. As a result of his confusion and preoccupation with the status of the glideslope,

failure to properly cross-check the airplane’s position and altitude with the

information on the approach chart, and continuing expectation of a visual approach,

the captain lost awareness of flight 801’s position on the instrument landing system

localizer-only approach to runway 6L at Guam International Airport and improperly

descended below the intermediate approach altitudes of 2,000 and 1,440 feet, which

was causal to the accident.

12. The first officer and flight engineer noted the ground proximity warning system

(GPWS) callouts and the first officer properly called for a missed approach, but the

captain’s failure to react properly to the GPWS minimums callout and the direct

challenge from the first officer precluded action that might have prevented the

accident.

13. The first officer and flight engineer failed to properly monitor and/or challenge the

captain’s performance, which was causal to the accident.

14. Monitored approaches decrease the workload of the flying pilot and increase flight

crew interaction, especially when experienced captains monitor and prompt first

officers during the execution of approaches.

15. The captain was fatigued, which degraded his performance and contributed to his

failure to properly execute the approach.

16. Korean Air’s training in the execution of nonprecision approaches was ineffective,

which contributed to the deficient performance of the flight crew.

17. U.S. air carrier pilots would benefit from additional training and practice in

nonprecision approaches during line operations (in daytime visual conditions in

which such a practice would not add a risk factor).

18. The Combined Center/Radar Approach Control controller’s performance was

substandard in that he failed to provide the flight crew with a position advisory when

he cleared the flight for the approach, inform the flight crew or the Agana tower

controller that he had observed a rain shower on the final approach path, and monitor

the flight after the frequency change to the tower controller.

19. Strict adherence to air traffic control procedures by the Combined Center/Radar

Approach Control controller may have prevented the accident or reduced its severity.
Conclusions 174 Aircraft Accident Report

20. If the ARTS IIA minimum safe altitude warning system had been operating as

initially intended, a visual and aural warning would have activated about 64 seconds

before flight 801 impacted terrain, and this warning would have likely alerted the

Combined Center/Radar Approach Control controller that the airplane was

descending below the minimum safe altitude for that portion of the approach.

21. Sixty-four seconds would have been sufficient time for the Combined Center/Radar

Approach Control controller to notify the Agana tower controller of the low-altitude

alert, the tower controller to convey the alert to the crew of flight 801, and the crew to

take appropriate action to avoid the accident.

22. The Federal Aviation Administration’s quality assurance for the minimum safe

altitude warning system was inadequate, and the agency’s intentional inhibition of

that system contributed to the flight 801 accident. 

23. A substantial portion of the delayed emergency response was caused by preventable

factors.

24. The delayed emergency response hampered the timely evacuation of injured persons,

and at least one passenger who survived the initial impact and fire might not have

died if emergency medical responders had reached the accident site sooner.

25. Improved formal coordination among Guam’s emergency response agencies has not

been implemented, and off-airport drills to identify and correct deficiencies in disaster

response planning before an accident occurs have still not been conducted in the more

than 2 years since the flight 801 accident.

26. Actions taken by Guam’s emergency response agencies after the accident have been

inadequate because they failed to ensure that emergency notifications and responses

would be timely and coordinated.

27. Controlled flight into terrain accident awareness and avoidance training is an

important accident reduction strategy and should be mandatory for all pilots operating

under 14 Code of Federal Regulations Part 121.

28. By providing vertical guidance along a constant descent gradient to the runway, the

use of on-board flight management system- and/or global positioning system-based

equipment can provide most of the safety advantages of a precision approach during a

nonprecision approach.

29. The safety of executing a nonprecision approach using the constant angle of descent,

or stabilized descent technique, would be enhanced by adding to approach charts the

cross-referenced altitudes versus distance from the airport.

30. Terrain depiction on the profile view of approach charts could result in increased

flight crew awareness of significant terrain on the approach path. 
Conclusions 175 Aircraft Accident Report

31. Valuable user group reviews of proposed new instrument procedures are hampered by

the format in which the information is disseminated; thus, user groups may not be

able to effectively evaluate whether a procedure is safe, accurate, and intelligible.

32. At the time of the flight 801 accident, there were underlying systemic problems

within Korean Air’s operations and pilot training programs that indicated the need for

a broad safety assessment of these programs.

33. The Korean Civil Aviation Bureau was ineffective in its oversight of Korean Air’s

operations and pilot training program.

34. The Federal Aviation Administration’s International Aviation Safety Assessment

program (which evaluates a foreign civil aviation authority’s ability to provide

adequate oversight for its air carriers) is not adequate to determine whether foreign air

carriers operating into the United States are maintaining an adequate level of safety.

35. An independent accident investigation authority, charged with making objective

conclusions and recommendations, is a benefit to transportation safety.

36. It is critical that thorough documentation of the information recorded by a flight data

recorder be available for foreign- or U.S.-registered air transport airplanes that fly

into or out of the United States.

3.2 Probable Cause

The National Transportation Safety Board determines that the probable cause of

this accident was the captain’s failure to adequately brief and execute the nonprecision

approach and the first officer’s and flight engineer’s failure to effectively monitor and

cross-check the captain’s execution of the approach. Contributing to these failures were

the captain’s fatigue and Korean Air’s inadequate flight crew training.

Contributing to the accident was the Federal Aviation Administration’s intentional

inhibition of the minimum safe altitude warning system at Guam and the agency’s failure

to adequately manage the system.
176 Aircraft Accident Report

4. Recommendations

As a result of the investigation of the Korean Air flight 801 accident, the National

Transportation Safety Board makes recommendations to the Federal Aviation

Administration, the Governor of the Territory of Guam, and the Korean Civil Aviation

Bureau.

To the Federal Aviation Administration:

Require principal operations inspectors assigned to U.S. air carriers to

ensure that air carrier pilots conduct a full briefing for the instrument

approach (if available) intended to back up a visual approach conducted at

night or when instrument meteorological conditions may be encountered.

(A-00-7)

Consider designating Guam International Airport as a special airport

requiring special pilot qualifications. (A-00-8)

Disseminate information to pilots, through the Aeronautical Information

Manual, about the possibility of momentary erroneous indications on

cockpit displays when the primary signal generator for a ground-based

navigational transmitter (for example, a glideslope, VOR, or nondirectional

beacon transmitter) is inoperative. Further, this information should

reiterate to pilots that they should disregard any navigation indication,

regardless of its apparent validity, if the particular transmitter was

identified as unusable or inoperative. (A-00-9)

Conduct or sponsor research to determine the most effective use of the

monitored approach method and the maximum degree to which it can be

safely used and then require air carriers to modify their procedures

accordingly. (A-00-10)

Issue guidance to air carriers to ensure that pilots periodically perform

nonprecision approaches during line operations in daytime visual

conditions in which such practice would not add a risk factor. (A-00-11)

Develop a mandatory briefing item for all air traffic controllers and air

traffic control (ATC) managers, describing the circumstances surrounding

the performance of the Combined Center/Radar Approach Control

controller in this accident to reinforce the importance of following ATC

procedures. (A-00-12)
Recommendations 177 Aircraft Accident Report

Require that all air carrier airplanes that have been equipped with on-board

navigational systems capable of providing vertical flightpath guidance

make use of these systems for flying nonprecision approaches whenever

terrain factors allow a constant angle of descent with a safe gradient.

(A-00-13)

Require, within 10 years, that all nonprecision approaches approved for air

carrier use incorporate a constant angle of descent with vertical guidance

from on-board navigation systems. (A-00-14)

Include, in nonprecision approach procedures, tabular information that

allows pilots to fly a constant angle of descent by cross-referencing the

distance from the airport and the barometric altitude. (A-00-15)

Evaluate the benefits of depicting terrain and other obstacles along a

specific approach path on the profile view of approach charts and require

such depiction if the evaluation demonstrates the benefits. (A-00-16)

Provide user groups, along with Federal Aviation Administration Form

8260, draft plan and profile views of instrument procedures to assist the

groups in effectively evaluating proposed new procedures. (A-00-17)

Consider the accident and incident history of foreign air carriers as a factor

when evaluating the adequacy of a foreign civil aviation authority’s

oversight and whether a reassessment may be warranted. (A-00-18)

To the Governor of the Territory of Guam:

Form, within 90 days, a task force comprising representatives from all

emergency response agencies on the island, including the appropriate

departments within the government of Guam, Federal Aviation

Administration, Guam International Airport Authority, U.S. Navy, U.S. Air

Force, U.S. Coast Guard, Federal Emergency Management Agency, and all

other affected agencies, to define and coordinate emergency notification

and response procedures to ensure that timely emergency notifications are

made to all local and Federal agencies according to need, location, and

response time capability. (A-00-19)

Require periodic and regularly scheduled interagency disaster response

exercises, including an off-airport aircraft accident scenario, in addition to

those response drills already required at Guam International Airport in

accordance with 14 Code of Federal Regulations Section 139.325.

(A-00-20)
Recommendations 178 Aircraft Accident Report

To the Korean Civil Aviation Bureau:

Require Korean Air to revise its video presentation for Guam to emphasize

that instrument approaches should also be expected and describe the

complexity of such approaches and the significant terrain along the

approach courses and in the vicinity of the airport. (A-00-21)

*Vice Chairman Francis requested that the following concurring statement be

added to this report:

“I concur in the report on Korean Air flight 801—a classic controlled-flight-intoterrain accident. I am troubled, however, by the failure to include a

recommendation that urges (1) timely installation of terrain awareness and

warning systems in accordance with the FAA’s reasonable proposed schedule;

(2) avoidance of any delay in the proposed regulatory schedule; and

(3) encouragement by the FAA to aircraft operators to install this critical safety

device in advance of the proposed regulatory timetable.”

BY THE NATIONAL TRANSPORTATION SAFETY BOARD

JAMES E. HALL

Chairman

JOHN A. HAMMERSCHMIDT

Member

ROBERT T. FRANCIS II*

Vice Chairman

JOHN J. GOGLIA

Member

GEORGE W. BLACK, JR.

Member

January 13, 2000
179 Aircraft Accident Report

5. Appendixes

Appendix A

Investigation and Hearing

Investigation

The Safety Board was initially notified of this accident about 1200 eastern

standard time on August 5, 1997 (about 0300 Guam local time on August 6). A full

go-team was assembled and departed that evening from Andrews Air Force Base in

Maryland for Fairchild Air Force Base in Washington. At Fairchild, the team boarded

another airplane and arrived in Guam about 0830 Guam local time on August 7, 1997.

Accompanying the team to Guam was Board Member George Black.

The following investigative teams were formed: Operations, Human Performance,

Aircraft Structures, Aircraft Systems, Powerplants, Maintenance Records, Air Traffic

Control, Survival Factors, Aircraft Performance, Meteorology, and Search/Fire/Rescue.

Specialists were also assigned to conduct the readout of the flight data recorder (FDR) and

transcribe the cockpit voice recorder (CVR) in the Safety Board’s laboratory in

Washington, D.C. The initial CVR transcript was produced in English. However, the

CVR group subsequently produced a more detailed transcript in both the English and

Korean languages.

Parties to the investigation were the Federal Aviation Administration (FAA);

Korean Air Company, Ltd.; Boeing Commercial Airplanes Group; Pratt & Whitney; the

National Air Traffic Controllers Association; and Serco Aviation Services, Inc. Assistance

was also provided by the U.S. Navy and emergency response personnel in Guam.

In addition, an official from the Korean Civil Aviation Bureau (KCAB) was

designated as the Korean Accredited Representative in accordance with the provisions of

Annex 13 to the Convention on International Civil Aviation. Further, two air safety

investigators from Australia’s Bureau of Air Safety Investigations participated in the

investigation as technical observers.

Hearing

A public hearing was conducted for this accident on March 24 through 26, 1998, in

Honolulu, Hawaii. Presiding over the hearing was Vice Chairman Robert Francis. Parties

to the public hearing were the FAA; Serco Aviation Services; Korean Air; Guam Civil

Defense, Fire Department, and Police Department; U.S. Navy; International Civil

Aviation Organization (ICAO) Controlled Flight Into Terrain Steering Committee;

AlliedSignal; Jeppesen Sanderson, Inc.; and the Air Line Pilots Association.
180 Aircraft Accident Report

Appendix B

Cockpit Voice Recorder Transcript

The following is a transcript of the Fairchild model A-100A CVR installed on

Korean Air flight 801 (a Boeing 747-300, HL7468), which crashed while approaching

Guam International Airport on August 6, 1997.

The CVR transcript reflects the final 31 minutes 1 second of the accident flight.

Times are expressed in coordinated universal time (UTC time), which is 10 hours behind

Guam local time. Only radio transmissions to and from the accident airplane were

transcribed. Items that were stated either partially or completely in the Korean language

are shown as two entries. The first, in bold type, is translated into the English language.

The second is typed as if it were spoken in Korean and/or English. Items with only one

entry were spoken entirely in English. 

LEGEND

CAM Cockpit area microphone voice or sound source

RDO Radio transmission from accident aircraft

NAV Navigation signal identifiers heard through aircraft audio system

PA Voice transmitted over aircraft public address system

CTR Radio transmission from Guam center controller

TWR Radio transmission from Guam tower controller

GPWS Voice identified as aircraft mechanical voice

-1 Voice identified as captain

-2 Voice identified as first officer

-3 Voice identified as flight engineer

.? Voice unidentified

• Unintelligible word

# Expletive

--- Break in continuity

( ) Questionable insertion

[ ] Editorial insertion

..... Pause




























209 Aircraft Accident Report

Appendix C

Flight Safety Foundation Study Recommendations

The Flight Safety Foundation Approach and Landing Accident (ALA) Reduction

Task Force made several recommendations to support each of its study’s nine conclusions

(see section 1.18.3.1 for more information). The conclusions and recommendations are as

follows: 

Conclusion 1: Establishing and adhering to adequate standard operating

procedures (SOP) and crew resource management (CRM) processes will improve

approach and landing safety.

Recommendations:

• States should mandate, and operators should develop and implement, SOPs

for approach and landing operations.

• Operators should develop SOPs that permit their practical application in a

normal operating environment. The involvement of flight crews is essential

in the development and evaluation of SOPs. Crews will adhere to SOPs that

they help develop and understand. 

• Operators should implement routine and critical evaluation of SOPs to

determine the need for change. 

• Operators should provide education and training that enhance flight crew

decision-making and risk (error) management. 

• Operators should develop SOPs regarding the use of automation in approach

and landing operations and train flight crews accordingly. 

• There should be a clear policy in all operators’ manuals regarding the role of

the pilot-in-command (PIC) in complex and demanding flight situations.

Training should address the practice of transferring pilot-flying duties during

operationally complex situations.

Conclusion 2: Improving communication and mutual understanding between air

traffic control (ATC) services and flight crews of each other’s operational

environment will improve approach and landing safety.

ATC recommendations: 

• Introduce joint training programs that involve both ATC personnel and flight

crews to promote mutual understanding of such issues as procedures,

instructions, operational requirements, and limitations; improve controllers’

knowledge of the capabilities and limitations of advanced-technology flight

decks; and foster improved communications and task management by pilots

and controllers during emergency situations. 

• Ensure that controllers are aware of the importance of unambiguous

information exchange, particularly during in-flight emergencies. The use of

standard ICAO phraseology should be emphasized. 
Appendix C 210 Aircraft Accident Report

• Implement procedures that require immediate clarification or verification of

transmissions from flight crews that indicate a possible emergency situation. 

• Implement procedures for ATC handling of aircraft in emergency situations to

minimize flight crew distraction. 

• Implement, in cooperation with airport authorities and rescue services,

unambiguous emergency procedures and common phraseology to eliminate

confusion. 

• Develop, jointly with airport authorities and local rescue services, emergency

training programs that are conducted on a regular basis. 

Flight crew recommendations:

• Verify understanding of each ATC communication and request clarification

when necessary. 

• Report accurately, using standard ICAO phraseology, the status of abnormal

situations and the need for emergency assistance. 

Conclusion 3: Unstabilized and rushed approaches contribute to ALAs.

Recommendations: 

• Operators should define the parameters of a stabilized approach in their flight

operations manuals, including at least the following: intended flightpath,

speed, power setting, attitude, sink rate, configuration, and crew readiness. 

• Company policy should state that a go-around is required if the aircraft

becomes destabilized during the approach. 

• The implementation of certified constant angle, stabilized approach

procedures for nonprecision approaches should be expedited globally. 

• Flight crews should be trained on the proper use of constant angle, stabilized

approach procedures. Flight crews should also be educated on approach

design criteria and obstacle clearance requirements. 

• Flight crews should “take time to make time” when the cockpit situation

becomes confusing or ambiguous, which means climbing, holding, requesting

vectors for delaying purposes, or performing a missed approach early. 

Conclusion 4: Failure to recognize the need for and to execute a missed approach,

when appropriate, is a major cause of ALAs. 

Recommendations:

• Company policy should specify well-defined go-around gates for approach

and landing operations. Parameters should include visibility minima required

before proceeding past the final approach fix or the outer marker, assessment

at the final approach fix or the outer marker of crew and aircraft readiness for

the approach, and minimum altitude at which the aircraft must be stabilized. 

• Companies should declare and support no-fault go-around and missed

approach policies. 
Appendix C 211 Aircraft Accident Report

Conclusion 5: The risk of ALAs is higher in operations conducted during low

light and poor visibility, on wet or otherwise contaminated runways, and with the

presence of optical physiological illusions. 

Recommendations: 

• Flight crews should be trained in operations involving these conditions before

being assigned line duties. 

• Flight crews should make operational use of a risk assessment tool or

checklist to identify approach and landing hazards. Appropriate procedures

should be implemented to mitigate the risks. 

• Operators should develop and implement constant angle, stabilized approach

procedures to assist crews during approach operations. 

• Operators should develop and implement a policy for the use of appropriate

levels of automation of navigation and approach aids for the approach being

flown. 

Conclusion 6: Using the radio altimeter as an effective tool will help prevent

ALAs. 

Recommendations:

• Education is needed to improve crew awareness of radio altimeter operation

and benefits. 

• Operators should install radio altimeters and activate “smart callouts” at

2,500, 1,000, and 500 feet; the altitude set in the decision height window; and

50, 40, 30, 20, and 10 feet for better crew terrain awareness. 

• Operators should state that the radio altimeter is to be used during approach

operations and specify procedures for its use. 

Conclusion 7: When the PIC is the pilot flying and the operational environment is

complex, the task profile and workload reduce the flying pilot’s flight

management efficiency and decision-making capability in approach and landing

operations. 

Recommendations:

• Operators should develop a clear policy in their manuals defining the role of

the PIC in complex and demanding flight situations.

• Training should address the practice of transferring pilot flying duties during

operationally complex situations.
Appendix C 212 Aircraft Accident Report

Conclusion 8: Collection and analysis of in-flight parameters (for example, flight

operations quality assurance programs) can identify performance trends that can

be used to improve the quality of approach and landing operations. 

Recommendations:

• Flight operations quality assurance should be implemented worldwide along

with information-sharing partnerships, such as the Global Analysis and

Information Network, British Airways Safety Information System, and FAA

Aviation Safety Action Programs. 

• Examples of flight operations quality assurance benefits (safety

improvements and cost reductions) should be widely publicized. 

• A process should be developed to bring flight operations quality assurance

and information-sharing partnerships to regional airlines and business

aviation. 

Conclusion 9: Global sharing of aviation information decreases the risk of ALAs. 

Recommendations:

• Deidentification of aviation information data sources should be a “cardinal

rule” in flight operations quality assurance and information-sharing processes. 

• Public awareness of the importance of information sharing must be increased

through a coordinated, professional, and responsible process.

The Flight Safety Foundation ALA task force said that its conclusions and

recommendations “must be translated into industry action” according to the following

principles: 

• cohesiveness across all aviation sectors and regions to participate jointly in

the implementation process and 

• commitment to a significant awareness campaign that will ensure availability

of this information to participants in approach and landing operations

worldwide so that they can play a part in improving safety within their

“spheres of influence.”