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Permit No. G-200

Aircraft Accident Report

Crash During Approach to Landing

Air Tahoma, Inc., Flight 185

Convair 580, N586P

Covington, Kentucky

August 13, 2004

NTSB/AAR-06/03

PB2006-910403 National Transportation Safety Board

Notation 7778 490 L’Enfant Plaza, S.W.

Adopted May 2, 2006 Washington, D.C. 20594

E PLUR IBUS UNUM

NATIONAL TRA S PORTATION

B OAR D

SAFE T Y

N
National Transportation Safety Board. 2006. Crash During Approach to Landing, Air Tahoma,

Inc., Flight 185, Convair 580, N586P, Covington, Kentucky, August 13, 2004. Aircraft Accident

Report NTSB/AAR-06/03. Washington, DC.

Abstract: This report explains the accident involving Air Tahoma, Inc., flight 185, a Convair 580, N586P,

that crashed about 1 mile south of Cincinnati/Northern Kentucky International Airport, Covington,

Kentucky, while on approach to runway 36R. Safety issues discussed in this report focus on flight

crew performance, fuel crossfeed operations, operating with different fuel boost pump output

pressure settings, and cockpit voice recorder power source reliability. Safety recommendations

concerning these issues are addressed to the Federal Aviation Administration. A safety

recommendation concerning operating with different fuel boost pump output pressure settings is

addressed to Transport Canada.

The National Transportation Safety Board is an independent Federal agency dedicated to promoting aviation, railroad, 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, determine the probable causes of the accidents, issue safety recommendations, 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 on the Web at <http://www.ntsb.gov>. Other information about available publications also

may be obtained from the Web site or by contacting:

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490 L’Enfant Plaza, 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 PB2006-910403 from:

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The Independent Safety Board Act, as codified at 49 U.S.C. Section 1154(b), precludes the admission into evidence or use of Board reports

related to an incident or accident in a civil action for damages resulting from a matter mentioned in the report. 
iii Aircraft Accident Report

Contents

Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

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

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

1.2 Injuries to Persons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.3 Damage to Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.4 Other Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.5 Personnel Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.5.1 The Captain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.5.1.1 Flight Test Failure History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.5.2 The First Officer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.5.2.1 Flight Test Failure History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.6 Airplane Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.6.1 Electrical System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.6.2 Fuel System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.6.3 Fuel System Cockpit Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.6.3.1 Fuel System Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.6.3.2 Prop-Jet Convair Bulletin Regarding Fuel 

Boost Pump Output Pressures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.6.4 Weight and Balance Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.7 Meteorological Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.8 Aids to Navigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.9 Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.10 Airport Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.11 Flight Recorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.11.1 Cockpit Voice Recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.11.1.1 Cockpit Voice Recorder Power Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1.11.1.2 Safety Recommendation A-99-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1.11.2 Flight Data Recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

1.11.3 Safety Recommendation A-00-30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

1.12 Wreckage and Impact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

1.12.1 General Wreckage Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

1.12.2 Fuel Tank System Components and Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

1.13 Medical and Pathological Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1.14 Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1.15 Survival Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

1.16 Tests and Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

1.16.1 November 2004 Fuel Boost Pump Examinations

and Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

1.16.2 April 2005 Fuel Boost Pump Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Contents iv Aircraft Accident Report

1.17 Organizational and Management Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

1.17.1 Flight Paperwork Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

1.17.2 Air Tahoma Fuel Crossfeed Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

1.17.2.1 Airplane Manufacturer Fuel Crossfeed Procedures. . . . . . . . . . . . . . . . . . . . . . . 25

1.17.2.2 Nolinor Aviation Fuel Crossfeed Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

1.17.3 Air Tahoma Engine Flameout Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

1.17.4 Postaccident Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

1.18 Additional Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

1.18.1 Previous Convair 580 In-Flight Fuel Imbalance Incident . . . . . . . . . . . . . . . . . . . . 27

2. Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.2 The Captain’s Preflight Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.3 Accident Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.4 Convair 580 Fuel Crossfeed Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.5 Dual Engine Power Loss. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.6 Differential Fuel Boost Pump Output Pressures Settings. . . . . . . . . . . . . . . . . . . . . . . . 33

2.7 Cockpit Voice and Image Recorder Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

3. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.1 Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.2 Probable Cause . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

4. Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4.1 New Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4.2 Previously Issued Recommendation Being Reiterated in This Report. . . . . . . . . . . . . . 39

5. Appendixes

A: Investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

B: Cockpit Voice Recorder Transcript . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
v Aircraft Accident Report

Figures

1. Schematic of the Convair 580 fuel system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2. The Convair 580 fuel panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3. The Convair 580 fuel quantity indicators and center pedestal. . . . . . . . . . . . . . . . . . . . . . . . 11
vi Aircraft Accident Report

Abbreviations

A&P airframe and powerplant

AFM aircraft flight manual

agl above ground level

ARTS automated radar terminal system

ASOS automated surface observing system

ATC air traffic control

ATCT air traffic control tower

ATP airline transport pilot

CAM cockpit area microphone

CFR Code of Federal Regulations

CG center of gravity

CVG Cincinnati/Northern Kentucky International Airport

CVR cockpit voice recorder

DME distance measuring equipment

FAA Federal Aviation Administration

FARs Federal Aviation Regulations

FDR flight data recorder

FOM flight operations manual

fpm feet per minute

GOM general operations manual

GPWS ground proximity warning system

lbs pounds

MEM Memphis International Airport

MSAW minimum safe altitude warning 

NDB nondirectional beacon

NPRM notice of proposed rulemaking
Abbreviations vii Aircraft Accident Report

PIC pilot-in-command

PJCB Prop-Jet Convair Bulletin 

PPI Pacific Propeller, Inc.

psi pounds per square inch

QRH quick reference handbook

SDR service difficulty report

STC supplemental type certificate

TC Transport Canada

TRACON terminal radar approach control

TSB Transportation Safety Board of Canada

VOR very high frequency omnidirectional range
viii Aircraft Accident Report

Executive Summary

On August 13, 2004, about 0049 eastern daylight time, Air Tahoma, Inc.,

flight 185, a Convair 580, N586P, crashed about 1 mile south of Cincinnati/Northern

Kentucky International Airport (CVG), Covington, Kentucky, while on approach to

runway 36R. The first officer was killed, and the captain received minor injuries. The

airplane was destroyed by impact forces. The flight was operating under the provisions of

14 Code of Federal Regulations Part 121 as a cargo flight for DHL Express from

Memphis International Airport, Memphis, Tennessee, to CVG. Visual meteorological

conditions prevailed for the flight, which operated on an instrument flight rules flight plan.

The National Transportation Safety Board determines that the probable cause of

this accident was fuel starvation resulting from the captain’s decision not to follow

approved fuel crossfeed procedures. Contributing to the accident were the captain’s

inadequate preflight planning, his subsequent distraction during the flight, and his late

initiation of the in-range checklist. Further contributing to the accident was the flight

crew’s failure to monitor the fuel gauges and to recognize that the airplane’s changing

handling characteristics were caused by a fuel imbalance. 

The safety issues discussed in this report include flight crew performance, fuel

crossfeed operations, operating with different fuel boost pump output pressure settings,

and cockpit voice recorder power source reliability. Safety recommendations concerning

these issues are addressed to the Federal Aviation Administration. A safety

recommendation concerning operating with different fuel boost pump output pressure

settings is addressed to Transport Canada.
1 Aircraft Accident Report

1. Factual Information

1.1 History of Flight

On August 13, 2004, about 0049 eastern daylight time,1 Air Tahoma, Inc.,

flight 185, a Convair 580, N586P, crashed about 1 mile south of Cincinnati/Northern

Kentucky International Airport (CVG), Covington, Kentucky, while on approach to

runway 36R. The first officer was killed, and the captain received minor injuries. The

airplane was destroyed by impact forces. The flight was operating under the provisions of

14 Code of Federal Regulations (CFR) Part 121 as a cargo flight for DHL Express2

 from

Memphis International Airport (MEM), Memphis, Tennessee, to CVG. Visual

meteorological conditions prevailed for the flight, which operated on an instrument flight

rules flight plan.

The flight crew was scheduled to fly the accident airplane on a roundtrip sequence

from MEM to CVG.3

 Flight 185 departed MEM about 2329. The first officer was the

flying pilot, and the captain performed the nonflying pilot duties. During postaccident

interviews, the captain stated that the takeoff and climb portions of the flight were normal. 

According to the cockpit voice recorder (CVR) transcript, at 0017:49, the captain

stated that he was just going to “balance out the fuel here.”4 The first officer

acknowledged. From 0026:30 to 0027:08, the CVR recorded the captain discussing the

airplane’s weight and balance with the first officer. Specifically, the captain stated,

“couldn’t figure out why on the landing I was out and I was okay on the takeoff.” The

captain added, “the momentum is one six six seven and I...put one zero six seven and I

couldn’t work it.” He then stated, “so...we were okay all along.”5

At 0030:40, the first officer stated, “weird.” At 0032:31, the captain stated, “okay

just let me finish this [the weight and balance paperwork] off and...I’m happy,” and, about

2 minutes later, he stated, “okay, back with you here.” At 0037:08, the captain contacted

Cincinnati Terminal Radar Approach Control (TRACON) and reported an altitude of

11,000 feet mean sea level.6

 About 1 minute later, the first officer stated, “something’s

messed up with this thing,” and, at 0039:07, he asked “why is this thing?” At 0041:21, the

1 Unless otherwise indicated, all times in this report are eastern daylight time.

2 Under a lease agreement, Air Tahoma supplied flight crews and airplanes to DHL to carry freight

between several cities on a scheduled basis.

3 The roundtrip sequence departed MEM every night, Monday through Friday, about 2300. The return

flight typically departed CVG about 0400.

4 Fuel crossfeeding operations are conducted by the flight crew to balance out the fuel in the airplane’s

fuel tanks. For more information about fuel crossfeed operations procedures, see section 1.17.2. 

5 For more information about the airplane’s weight and balance and the captain’s calculations see

section 1.6.3. 

6 Unless otherwise indicated, all altitudes in this report are referenced in mean sea level.
Factual Information 2 Aircraft Accident Report

first officer stated that the control wheel felt “funny.” He added, “feels like I need a lot of

force. it is pushing to the right for some reason. I don’t know why...I don’t know what’s

going on.” The first officer then repeated twice that it felt like he needed “a lot of force.”

The CVR did not record the captain responding to any of these comments. 

At 0043:53, when the airplane was at an altitude of about 4,000 feet, the captain

reported to Cincinnati TRACON that he had the runway in sight. The approach controller

cleared flight 185 for a visual approach to runway 36R and added, “keep your speed up.”7

The captain acknowledged the clearance and the instruction. The first officer then stated,

“what in the world is going on with this plane? sucker is acting so funny.” The captain

replied, “we’ll do a full control check on the ground.” At 0044:43, the approach controller

again told the captain to “keep your speed up” and instructed him to contact the CVG Air

Traffic Control Tower (ATCT). 

At 0045:11, the captain contacted the CVG ATCT and requested clearance to land

on runway 36R, and the local control west controller issued the landing clearance. Flight

data recorder (FDR) data indicated that, shortly afterward, the airplane passed through

about 3,200 feet, and its airspeed began to decrease from about 240 knots indicated

airspeed. At 0045:37, when the airplane was at an altitude of about 3,000 feet, the captain

started the in-range checklist,8

 stating, “bypass is down. hydraulic pressure. quantity

checks. AC [alternating current] pump is on. green light. fuel panel. boost pumps on.” 

About 0046, the first officer stated, “I’m telling you, what is wrong with this

plane? it is really funny. I got something all messed up here.” The captain replied, “yeah.”

The first officer then asked, “can you feel it? it’s like swinging back and forth.” The

captain replied, “we’ve got an imbalance on this...crossfeed I left open.” The first officer

responded, “oh, is that what it is?” A few seconds later, the first officer stated, “we’re

gonna flame out.” The captain responded, “I got the crossfeed open. just keep power on.” 

At 0046:45, the CVR recorded a sound similar to decreasing engine rpm.

Immediately thereafter, the first officer stated, “we’re losing power.” At 0046:52, the first

officer stated, “we’ve lost both of them. did we?” The captain responded, “nope.” FDR

data showed that, about 1 second later, a momentary electrical power interruption

occurred when the airplane was at an altitude of about 2,400 feet. At 0046:55, the CVR

stopped recording. Airplane performance calculations indicated that, shortly after the

power interruption, the airplane’s descent rate was about 900 feet per minute (fpm). 

According to air traffic control (ATC) transcripts, at 0047:12, the captain reported

to the CVG ATCT that the airplane was “having engine problems.” The local control west

controller asked, “you’re having engine problems?” The captain replied, “affirmative.” At

7 During postaccident interviews, the approach controller stated that he instructed the flight crew to

“keep the speed up” because he thought that Air Tahoma flight crews had a tendency to decrease the

airspeed too early in the approach and that he wanted to prevent that from occurring.

8 Air Tahoma’s Flight Operations Manual (FOM) states that the in-range checklist should be

performed before “leaving 12,000 feet” and that “early completion [of the checklist] will minimize cockpit

distractions.” The in-range checklist includes a step to check the fuel panel settings. For a schematic of the

Convair 580 fuel panel, see section 1.6.2.1, figure 2. 
Factual Information 3 Aircraft Accident Report

0047:28, the controller asked the captain if he needed emergency equipment, and the

captain replied, “negative.’” This was the last transmission received by ATC from the

accident flight crew. The FDR continued recording until about 0049. The wreckage was

located about 1.2 miles short of runway 36R.

1.2 Injuries to Persons

Table 1. Injury chart.

Note: Title 14 CFR 830.2 defines a serious injury as any injury that (1) requires hospitalization for more than 48 hours, 

starting within 7 days from the date that the injury was received; (2) results in a fracture of any bone, except simple 

fractures of fingers, toes, or the nose; (3) causes severe hemorrhages or nerve, muscle, or tendon damage; (4) involves 

any internal organ; or (5) involves second- or third-degree burns or any burns affecting more than 5 percent of the body 

surface. A minor injury is any injury that does not qualify as a fatal or serious injury.

1.3 Damage to Airplane

The airplane was destroyed by impact forces.

1.4 Other Damage

Trees and a portion of a golf course along the wreckage path were damaged by the

impact.

1.5 Personnel Information

1.5.1 The Captain

The captain, age 49, was hired by Air Tahoma on July 19, 2004. The captain held

both Federal Aviation Administration (FAA)- and Transport Canada (TC)-issued pilot

licenses and certificates.9

 The captain’s FAA-issued certificates included an airframe and

powerplant (A&P) certificate (issued February 25, 1982), a flight engineer certificate

(issued January 26, 1988),10 and a multiengine airline transport pilot (ATP) certificate

Injuries Flight Crew Cabin Crew Passengers Other Total

Fatal 1 0 0 01

Serious 0 0 0 00

Minor 1 0 0 01

None 0 0 0 00

Total 2 0 0 02

9 The captain is a citizen of Canada.
Factual Information 4 Aircraft Accident Report

(issued February 11, 2003) with a Convair 340/440 type rating (issued May 9, 2003).11

The captain held a first-class FAA airman medical certificate, dated April 16, 2004, with

the limitation that he “must possess glasses for near vision.” The captain’s TC-issued

certificates included a flight engineer certificate (issued December 28, 1983) and a

commercial pilot certificate (issued May 7, 1997). The captain had Canadian aircraft

(type) ratings in the Convair 580 and the Lockheed L-1011. Table 2 shows the

employment information reported by the captain on the job application that he filled out

for Air Tahoma.

Table 2. Employment information for the captain.

a

 The captain began working for Air Transat as a flight engineer. He upgraded to first officer in May 1999. He flew a total of 

about 104 hours before cutbacks at Air Transat caused him to return to the flight engineer position. In December 2003, the 

captain failed a first officer requalification proficiency checkride, and he chose to receive a severance package from Air 

Transat rather than return to the flight engineer position. 

b

 While working at Air Transat, the captain took leave to fly under contract as first officer or captain for various companies.

10 The flight engineer certificate was a special purpose lessee with the limitation that the certificate was

valid for U.S.-registered civil Lockheed L-1011s leased to Gulf Air Airlines, Bahrain, United Arab

Emirates. The certificate was issued under and subject to 14 CFR 63.23 and subject to the privileges and

limitations shown on the holder’s foreign flight engineer certificate, license, or authorization.

11 The FAA uses the rating designation “Convair 340/440” on a pilot’s airman certificate when the pilot

is rated in the Convair 340/440 or the Convair 580. 

Employment date Employer Job position Airplane type

1981 to 1983 Chevron Corporation, 

Khartoum, Sudan

Maintenance 

engineer

Convair 580

1983 to 1985 Northwest Territorial Airways, 

Yellowknife, Northwest 

Territories, Canada

Flight engineer Lockheed 

Electra

1985 to 1987 Nationair, Montreal, Canada Flight engineer Douglas DC-8

1987 to 1993 Gulf Air Airlines, Bahrain, 

United Arab Emirates, and All 

Nippon Airways, Tokyo, Japan 

Flight engineer Lockheed

L-1011

April 1993 to December 

2003

Air Transat, Montreal, Canada Flight engineer/first 

officera

Lockheed 

L-1011

1998 (6 months) Air Wave Transport, Toronto, 

Canada

First officer Convair 580

1999 to 2003 (several 

months per year)b

Nolinor Aviation, Montreal, 

Canada

First officer Convair 580

November 2002 to July 

2003

Coastal Air Transport, Mobile, 

Alabama

Captain Convair 580

Summer 2003 ConAir, Abbotsford, British 

Columbia, Canada

First officer Convair 580
Factual Information 5 Aircraft Accident Report

Air Tahoma records indicated that the captain had accumulated 2,500 total flight

hours, including 1,337 hours in the Convair 580, 88.5 hours of which were as

pilot-in-command (PIC). He had flown about 32, 28, and 2 hours in the 90 days, 30 days,

and 24 hours, respectively, before the accident. The captain’s last Convair 580 proficiency

and line checks occurred on July 29, 2004. In accordance with 14 CFR 121.405(d), the

captain attended an FAA-approved reduced training course at Air Tahoma because of his

previous Part 121 experience in the Convair 580 at Coastal Air Transport. A search of

FAA records indicated no accident or incident history or enforcement action, and a search

of the National Driver Register found no record of driver’s license suspension or

revocation.

The captain stated that, during the 72 hours before the accident, he stayed at Air

Tahoma’s crew house in Memphis. He stated that he typically slept until about noon after

returning from flights in the morning (about 0500 central daylight time). The captain

stated that, on the day of the accident, he watched television from about 1600 to

2100 central daylight time and then checked in at MEM for the accident flight. The

captain stated that he did not feel tired during the accident flight but that he was

“preoccupied” with and “stressed” about calculating the airplane’s weight and balance. A

company mechanic who routinely met both the captain and the first officer before and

after trips stated that they both appeared normal, alert, and “not dragging” before the

accident flight. The captain stated that he was in good health and that he did not take any

medications. 

1.5.1.1 Flight Test Failure History

On February 7, 2003, the captain received a notice of disapproval from the FAA

because he failed the precision instrument approach portion of the flight test for his ATP

certificate. On February 11, 2003, the captain was retested successfully, and he received

his ATP certificate. On May 8, 2003, the captain received a notice of disapproval from the

FAA because he failed the nondirectional beacon (NDB) approach portion of the flight test

for his Convair 580 type rating. On May 9, 2003, the captain was retested successfully,

and he received his Convair 580 type rating.

1.5.2 The First Officer

The first officer, age 37, was hired by Air Tahoma on May 5, 2004. The first

officer held an A&P certificate (issued May 8, 1996), a commercial pilot certificate with

single- and multiengine land ratings (issued February 7, 2002), and a flight instructor

certificate (issued April 10, 2002). The first officer held a first-class FAA airman medical

certificate dated December 16, 2003, with no limitations. Table 3 shows the employment

information reported by the first officer on the job application that he filled out for Air

Tahoma.
Factual Information 6 Aircraft Accident Report

Table 3. Employment information for the first officer.

a In August 2001, the first officer was laid off from Ryan International. In December 2002, Ryan International rehired him.

Air Tahoma and Ryan International records indicated that the first officer had

accumulated 2,488 total flight hours, 1,564 hours of which were as a flight engineer, and

924 hours of which were as PIC or first officer. The first officer had accumulated

145 hours in Convair 580 airplanes. He had flown about 145, 70, and 2 hours in the

90 days, 30 days, and 24 hours, respectively, before the accident. The first officer’s last

Convair 580 proficiency and line checks occurred on May 26, 2004. FAA records

indicated no accident or incident history or enforcement action, and a search of the

National Driver Register found no record of driver’s license suspension or revocation.

The first officer operated all of the flights from MEM to CVG from August 9

to 13, 2005, and all of these flights were in the accident airplane. According to a family

member, on August 12, the first officer returned home about 0700 central daylight time

and slept until about 1530 central daylight time. Later that day, he went to his son’s

football practice and ate dinner before checking in for the flight. A company mechanic

reported that the first officer appeared to be wide awake and alert before the flight and that

he had sufficient time to complete his preflight activities. The family member reported

that the first officer did not use alcohol or take any medications. 

1.5.2.1 Flight Test Failure History

On November 14, 2001, the first officer received a notice of disapproval from the

FAA because he failed the steep turns, compliance with departure and arrival procedures,

distance measuring equipment (DME) arc approach, and NDB approach portions of the

flight test for his instrument rating. The first officer was retested successfully on

November 19, 2001, and he received his instrument rating. On April 10, 2002, the first

officer received a notice of disapproval from the FAA because he failed the ground

reference maneuvers portion of the flight test for his flight instructor certificate. The first

officer was retested successfully that day, and he received his flight instructor certificate.

Employment date Employer Job position

Airplane 

type

January 1997 to August 2001 Ryan International Airlines, 

Wichita, Kansas

Flight engineer Boeing 727

April 2002 to March 2004 Douglas Aviation, Olive 

Branch, Mississippi

Flight instructor N/A

July 2002 to April 2003 Air Venture Flying Club, 

Olive Branch, Mississippi

Flight instructor Cessna 152 

and 172

December 2002a

 to February 2004 Ryan International Airlines Flight engineer Boeing 727
Factual Information 7 Aircraft Accident Report

1.6 Airplane Information

The accident airplane, serial number 068, was manufactured in 1953 by General

Dynamics, Convair Division, and was originally designated “Convair 340/440.” In 1967,

the airplane was made to comply with Supplemental Type Certificate (STC) SA41100,12

changing its designation to “Convair 580.”13

Air Tahoma purchased the airplane from European Air Transport in Belgium on

April 27, 2004; at which time, the airplane was flown to the company’s maintenance

facility at Rickenbacker International Airport, Columbus, Ohio. From April 28 to July 15,

2004, the airplane underwent a conformity and acceptance inspection, a C check

(maintenance inspection), and serial number verification before being operated in the

United States.14 Maintenance records indicate that, during these inspections, most of the

airplane’s replaceable components were replaced because of inadequate time and service

history information and that all of the fuel system components, except for the right fuel

boost pump, were replaced with overhauled units.15 The FAA issued a standard

airworthiness certificate for the airplane on July 14, 2004. At the time of the accident, the

airplane had accumulated about 67,886 total flight hours. 

The accident airplane was configured with five containerized pallets in the

fuselage for all-cargo operations.16 There were four cargo stops (one in each of the floor

tracks) at the aft and forward ends of the fuselage. Each cargo stop was secured to floor

tracks in the airplane’s interior by two latches. Four cargo locks, which raised up and

locked the pallets into position, were between each pallet (16 locks total). Each lock was

secured to the floor tracks by two latches.

In compliance with STC SA41100, the airplane was equipped with two

Rolls-Royce 501-D13D turbopropeller engines. The time since new for the left engine was

41,232 hours, and the time since overhaul was 4,808 hours. The time since new for the

right engine was 24,055 hours, and the time since overhaul was 1,858 hours. The airplane

was equipped with Aeroproducts model A6441FN-606A propellers. The right propeller

12 In 1960, STC SA41100 was developed to install two Rolls-Royce (formerly Allison Gas Turbines)

501-D13D turbopropeller engines on the Convair 340/440, and the airplane model’s designation was

changed to Convair 580. Currently, about 26 Convair 580 airplanes are in operation in the United States.

13 General Dynamics, Convair Division, held the Convair 580 type certificate until 1995; at which time,

the type certificate was transferred to Tracor Flight Systems. In 1998, the type certificate was transferred to

Kelowna Flightcraft Ltd., British Columbia, Canada.

14 The conformity and acceptance inspection was conducted in accordance with Air Tahoma’s FARs

[Federal Aviation Regulations] 121 Conformity Check and Acceptance Manual, dated January 8, 1999;

the C check was performed in accordance with Air Tahoma’s FAA-approved maintenance program; and the

serial number verification was performed in accordance with Air Tahoma’s FARs 121 Conformity CV-580

Serial Number Verification document.

15 Maintenance records indicated that the right fuel boost pump had been replaced by Canadian Aero

Accessories Ltd., Calgary, Alberta, Canada, in February 2003. For more information about the airplane’s

fuel system, see section 1.6.2.

16 The Convair 580 was originally configured as a 52-seat passenger airplane. 
Factual Information 8 Aircraft Accident Report

was overhauled in January 2002, and the left propeller was overhauled in May 2003 by

Pacific Propeller, Inc. (PPI),17 Kent, Washington.

1.6.1 Electrical System 

The airplane had a 28-volt d.c. electrical system and a 115/200-volt a.c. electrical

system. The d.c. electrical system had two engine-driven power generators, and the a.c.

electrical system had two engine-driven alternators. Each engine had one d.c. generator

and one a.c. alternator. The electrical system was designed to automatically revert to

battery power if both d.c. generators and a.c. alternators shut down in flight. When this

occurs, the a.c. electrical system is powered by the batteries through the d.c. electrical

system and an inverter. 

1.6.2 Fuel System 

The Convair 580 fuel system comprises two subsystems, one for each

wing-mounted engine. Each fuel subsystem has a wing fuel tank, which is fueled through

a fuel filler cap and mating adaptor located under a cover plate on the upper surface of

each wing.18 Fuel is supplied from each fuel tank via fuel lines, which pass through the

tank wall, a fuel tank shutoff valve, and an electric fuel boost pump, to its respective

engine. (Figure 1 shows a schematic of the Convair 580 fuel system.) The electric fuel

boost pump supplies pressurized fuel to its respective engine and to the crossfeed fuel line.

The fuel boost pump supplies fuel at an output pressure of about 15 to 21 pounds per

square inch (psi) at a rate of about 640 gallons per hour. The airplane’s two fuel

subsystems are connected by a crossfeed system consisting of two electrically operated

crossfeed valves, which allows both engines to be supplied with fuel from either fuel

tank.19

17 PPI holds the type certificate for the propellers.

18 Each fuel tank has an 865-gallon capacity, four capacitance transmitters, and one compensator for

fuel quantity indication in the cockpit.

19 For information about Air Tahoma’s fuel crossfeed procedures, see section 1.17.2.
Factual Information 9 Aircraft Accident Report

Figure 1. Schematic of the Convair 580 fuel system.

1.6.3 Fuel System Cockpit Instrumentation

The airplane’s fuel system cockpit instrumentation includes the fuel panel, fuel

quantity indicators, and fuel system warning annunciator lights. The fuel panel, which is

located on the captain’s overhead instrument panel, has an emergency power-off switch

and three cover-guarded switches: two fuel tank shutoff valve switches and one fuel

crossfeed valve switch. Figure 2 shows the Convair 580 fuel panel.

L.M. EMERGENCY

MECHANICAL CONTROLS

DRAIN LINES

R.M. EMERGENCY

CROSSFEED VALVE

FUEL TANK

SHUTOFF 

VALVES

EMER. FIREWALL

SHUTOFF VALVE

ENGINE FUEL BOOST PUMP

A.C. BOOST PUMP

PRESSURE SWITCH

LEFT WING

LEFT ENGINE

RIGHT WING

RIGHT ENGINE

ENGINE-DRIVEN

FUEL PUMP
Factual Information 10 Aircraft Accident Report

Figure 2. The Convair 580 fuel panel.

The fuel quantity indicators are located on the lower part of the center instrument

panel and behind the center pedestal, which includes the engine throttle control console

and the gust lock levers. (Figure 3 shows the fuel quantity indicators behind the center

pedestal.) The three fuel system warning annunciator lights for each engine (primary fuel

pump failure, low engine fuel boost pressure, and aircraft fuel boost pressure) are located

on the center pedestal annunciator panel. 

CIRCUIT BREAKERS 

For the respective valve. 

NOTE:

Power for those circuit breakers 

comes from the Fuel Shut Off Valves

Circuit Breaker on the Essential D.C.

Bus. 

TANK SHUT OFF VALVE SWITCHES

Opens and closes the respective motor

acutated fuel tank shut off valve.

FUEL CROSS FEED VALVE SWITCH

Opens and closes both motor actuated 

cross feed valves. 

EMERGENCY POWER OFF SWITCH

Turn power on and off to the cross feed

and fuel tank shut off valves. Because

they are motor actuated valves, these

valves will remain in the position they are

in at the time this switch is turned off. 

FUEL TRANSFER FROM TANK TO

TANK IS PROHIBITED WHEN

OPERATING WITH THE CROSSFEED 

SYSTEM. TURN OFF FUEL VALVE 

FOR TANK NOT BEING USED. 

FUEL PANEL

FUEL TANK No1 FUEL TANK No2

CROSS

FEED

VALVES

CLOSED

CROSS FEED

VALVES

NORMAL

OFF

O

P

E

N

C

L

S

E

D

O

P

E

N

C

L

S

E

D

O

P

E

N

SHUT OFF

VALVES

LH RH

LH RH

EMERGENCY SHUT OFF VALVES

POWER OFF

ENG

NO. 1

ENG

NO. 2
Factual Information 11 Aircraft Accident Report

Figure 3. The Convair 580 fuel quantity indicators and center pedestal.

Postaccident interviews with Air Tahoma personnel and an inspection of another

Convair 580 revealed that, at some seat positions, it was difficult to see the fuel quantity

indicators. Specifically, if the seats were in an aft position, the indicators were difficult to

see because the throttle control console and the gust lock lever partially blocked the

indicators. The inspection revealed that, in the aft position, a pilot had to sit up and lean

forward to completely see the fuel quantity indicators. 

1.6.3.1 Fuel System Limitations

The FAA-approved Aircraft Flight Manual (AFM), dated April 5, 1962,20 contains

the following caution:

DO NOT ATTEMPT TO TRANSFER FROM ONE TANK TO ANOTHER. TO

DO SO MIGHT BUILD UP EXCESSIVE PRESSURE IN A TANK, WHICH

COULD RESULT IN STRUCTURAL FAILURE OR CAUSE FUEL TO

OVERFLOW THROUGH THE VENTS.

20 The AFM used by Air Tahoma was issued by the airplane manufacturer, General Dynamics, Convair

Division.

Fuel Quantity Indicators
Factual Information 12 Aircraft Accident Report

The Convair 580 type certificate data sheet indicated that a placard stating, “Fuel

transfer from tank to tank is prohibited. When operating with the crossfeed system, turn

off fuel valve for tank not being used,” must be displayed on the instrument panel in full

view of the pilot. The Air Tahoma CV-580 Flight Operations Manual (FOM),

Section 1.000, “Limitations,” states that transferring fuel from one tank to another tank is

prohibited and that crossfeeding fuel is prohibited during takeoff and landing (unless an

engine cannot be fed from its respective tank). The manual states that the maximum

permissible lateral fuel imbalance in flight is 2,080 pounds (lbs) and that the maximum

demonstrated lateral fuel imbalance during takeoff and landing is 600 lbs.

1.6.3.2 Prop-Jet Convair Bulletin Regarding Fuel Boost Pump Output 

Pressures

Prop-Jet Convair Bulletin (PJCB) 10-21, “Aircraft Fuel Boost Pump Output

Pressure Limit-Reduce,” dated October 10, 1969, provided details on an optional

procedure that allowed Convair operators to reduce the typical fuel boost pump output

pressure setting of 21 psi to 15 psi. The bulletin stated that reducing the output pressure

would “improve the service life of the aircraft fuel boost pump motors.” The bulletin also

stated that the low fuel boost pump pressure warning switch would have to be replaced

with a switch that would actuate at a decreasing pressure of 9 psi and an increasing

pressure of 10 psi. The bulletin stated that, although aircraft could be operated with

different fuel boost pump output pressure settings and switches, “preferably, aircraft

should be operated with identical boost pump pressure settings and switches, of either

configuration, on both sides.”

Postaccident examinations revealed that the accident airplane’s right fuel boost

pump was set to an output pressure of 15 psi21 and that its left fuel boost pump was set to

an output pressure of 20 psi. Air Tahoma stated that it was unaware of PJCB 10-21, and,

therefore, was not aware of the possibility that its Convair 580 airplanes were operating

with different fuel boost pump output pressure settings. In its July 18, 2005, submission,

Air Tahoma indicated that, after the accident, the company checked all of its airplanes’

fuel boost pump pressure output pressure settings and switches and set all of the output

pressure settings to 21 psi. 

1.6.4 Weight and Balance Information

Title 14 CFR 121.665, “Load Manifest,” states, in part, the following:

Each certificate holder is responsible for the preparation and accuracy of a load

manifest form before each takeoff. The form must be prepared and signed for each

flight by employees of the certificate holder who have the duty of supervising the

loading of aircraft and preparing the load manifest forms or by other qualified

persons authorized by the certificate holder.

21 Examinations also revealed that the airplane’s right low boost pump pressure warning switch was set

at 9 psi. For more information about the postaccident fuel boost pump examinations, see section 1.16.1.
Factual Information 13 Aircraft Accident Report

Title 14 CFR 121.693, “Load Manifest: All Certificate Holders,” states, in part,

that the load manifest must contain the weight of the aircraft, fuel and oil, cargo and

baggage, passengers, and crewmembers; the maximum allowable weight for the flight; the

total weight calculated using FAA-approved company procedures; and evidence that the

aircraft was loaded in accordance with an approved schedule that ensures that the CG is

within limits. Title 14 CFR 121.695, “Disposition of Load Manifest, Dispatch Release,

and Flight Plans: Domestic and Flag Operations,” states, in part, that the pilot must carry

copies of the completed load manifest, dispatch release, and flight plan in the airplane. 

Two load manifests were found at the accident site; however, the captain did not

leave a load manifest at the departure station, which is required by company procedures

and Federal regulations.22 The captain stated during postaccident interviews that he

usually left a yellow copy of the load manifest at the departure station. However, the

captain stated that he did not leave a copy of the load manifest at MEM before the accident

flight departed because he had to manually calculate the airplane’s weight and balance,

and the calculations were not completed before takeoff.23

The captain left a signed copy of a load sheet,24 which showed the weight of the

cargo loaded in each of the airplane’s five cargo containers (labeled A through E) and the

location at which each container should be loaded on the airplane, with the cargo loaders

at MEM. He stated that the total cargo weight was not near the maximum allowable. He

added that the load was “an average load” and that he used his “general experience” to

determine whether the airplane was within weight and balance limits before takeoff. For

example, the captain stated that, during the preflight check, he noted that the airplane sat

“properly” on the nose landing gear strut.

Both load manifests found at the accident site had the accident flight number,

accident flight date, and numerous crossouts on them. One of the manifests was not signed

by the captain and indicated weights and cargo locations that corresponded to those on the

load sheet he left at MEM. The other load manifest was signed by the captain and did not

indicate weights and cargo locations that corresponded to those on the load sheet. Table 4

shows the information listed on each of the load manifests found at the accident site.

22 For more information about Air Tahoma’s procedures on the preparation and disposition of weight

and balance paperwork, see section 1.17.1.

23 Air Tahoma’s handheld company computer was not working before the flight departed. Air Tahoma’s

ground school instructor stated the captain was not trained to manually compute an airplane’s weight and

balance because he had attended the company’s reduced training course. In its submission, Air Tahoma

indicated that, after the accident, the company provided followup training to its flight crewmembers on how

to compute weight and balance with and without the handheld computer and emphasized the importance of

leaving a copy of the weight and balance paperwork at the departure station. 

24 The load sheet that the captain left at MEM was not an official document nor was it mentioned in

company manuals or procedures; rather, it was an informal document used between Air Tahoma flight crews

and cargo loaders. 
Factual Information 14 Aircraft Accident Report

Table 4. Accident airplane weight and balance information.

a According to Air Tahoma’s Convair 580 Cargo Weight & Balance Loading Manual, the maximum certificated takeoff 

weight for the accident airplane was 58,156 lbs.

b A moment is a force that tries to cause rotation and is the product of weight (in pounds) and distance from the CG (in 

inches).

c Using the CV-580 CG Limits Table contained in the Air Tahoma loading manual and assuming a takeoff weight of about 

54,200 lbs, Safety Board investigators determined that the takeoff CG limits for the accident flight were about 

20,408 forward and 21,127 aft.

d

 The fuel burn moment appeared to have been written as 1,067 and then rewritten as 1,667. According to Air Tahoma’s 

Convair 580 Cargo Weight & Balance Loading Manual, the correct moment for a fuel burn of 4,200 lbs was 1,667.

e

 The landing moment of 20,030 corresponds to the originally written fuel burn moment of 1,067, and the landing moment of 

19,430 corresponds to the rewritten fuel burn moment of 1,667.

1.7 Meteorological Information 

Weather observations at CVG were made every hour by an automated surface

observing system (ASOS).25 About 0015, the ASOS reported that visibility was 10 statute

miles, clouds were overcast at 7,500 feet above ground level (agl), and winds were 320° at

5 knots. 

1.8 Aids to Navigation

The DME on the CVG VOR26 was inoperative. No problems with any other

navigational aids were reported.

Unsigned load manifest Signed load manifest

Cargo weight (pounds) 12,400 12,400

Fuel weight (pounds) 7,600 7,900

Takeoff weight (pounds) 54,213a 54,513

Takeoff moment/1,000b 21,073 21,118

Takeoff center of gravity (CG) limits 

(moment/1,000)c 19,638 (forward)/20,386 (aft) 20,571 (forward)/21,283 (aft)

Fuel burn (pounds) 4,200 4,200

Fuel burn moment/1,000 1,067/1,667d 1,667

Landing weight (pounds) 50,013 50,313

Landing moment/1,000 20,030/19,430e 19,451

Landing CG limits (moment/1,000) 18,752 (forward)/19,529 (aft) 18,872 (forward)/19,645 (aft)

25 ASOS is a system that continuously measures weather information, including wind speed and

direction, visibility, precipitation, cloud cover, temperature, dew point, and altimeter setting.

26 VOR stands for very high frequency omnidirectional range.
Factual Information 15 Aircraft Accident Report

1.9 Communications

No communications problems between the pilots and any of the air traffic

controllers who handled the accident flight were reported. 

1.10 Airport Information

CVG is located about 9 miles south of Cincinnati, Ohio, at an elevation of

896 feet. The airport has three runways: runway 18L/36R, 18R/36L, and 9/27. All of the

runways have high-intensity runway and centerline lights. Runway 18L/36R has a

standard 2,400-foot, high-intensity lighting system with sequenced flashers27 and a

precision approach path indicator on its right side. 

CVG is equipped with an automated radar terminal system (ARTS)-IIIA radar data

processing system, which includes a minimum safe altitude warning (MSAW) capability

that monitors aircraft separation from terrain and other obstacles. If an aircraft descends

below or is predicted to descend below a prescribed minimum altitude, the MSAW

provides air traffic controllers with both visual and aural alerts. The minimum altitude at

which the MSAW alerts controllers varies according to geographic location. CVG’s

ARTS-III system did not activate an MSAW alert around the time of the accident.28

1.11 Flight Recorders

1.11.1 Cockpit Voice Recorder

The accident airplane was equipped with a Honeywell Sundstrand V557 model

CVR, serial number 2372. The exterior of the CVR was not structurally damaged. The

CVR was sent to the Safety Board’s laboratory in Washington, D.C., for readout and

evaluation. The tape was played back normally and without difficulty. The recording

started at 0016:03 and continued until 0046:55. 

The recording consisted of three separate channels of audio information: the

captain and first officer audio panels and the cockpit area microphone (CAM). The captain

audio panel information was excellent quality, the first officer audio panel information

was good quality, and the CAM information was poor quality.29 A transcript was prepared

of the entire 30-minute, 52-second recording (see appendix B).

27 A notice to airmen recorded by the CVR at 0030:41 indicated that the sequenced flashers on

runway 36R were out of service.

28 Radar coverage of the accident airplane should have been available to the ground; however, the

airplane descended below radar coverage before the ARTS-III system could detect whether the airplane was

below the minimum safe altitude or predict whether it would descend below the minimum safe altitude. 

29 The Safety Board rates the quality of CVR recordings according to a five-category scale: excellent,

good, fair, poor, and unusable. See appendix B for a description of these ratings. 
Factual Information 16 Aircraft Accident Report

1.11.1.1 Cockpit Voice Recorder Power Source

Title 14 CFR 121.359(a) requires airplanes to be equipped with a CVR system that

operates “continuously from the start of the use of the checklist (before starting engines

for the purpose of flight) to completion of the final checklist at the termination of the

flight.” The CVR on the accident airplane was installed in 1966 by Allegheny Airlines,

Inc., Middleton, Pennsylvania, in accordance with Engineering Order 66-16c, Revision A,

which required changing the wiring “to provide an isolated power source for the

[CVR]...to comply with FAR [Federal Aviation Regulations] 121.359.” 

The accident CVR was designed to receive sufficient power to operate when both

engine power levers are at or above flight idle. When the engine power levers are in the

low-speed range or shut down and the low-rpm buttons, which are located on the center

pedestal, are pushed in by the flight crew, the low-rpm relays are energized, and the

batteries provide power to the CVR.30 However, when both engines are in the low-speed

range or shut down and the low-rpm buttons are not pushed in by the pilot, no power is

provided to the CVR. 

1.11.1.2 Safety Recommendation A-99-16

On March 9, 1999, as a result of its longstanding concerns about the loss of critical

flight information following interruption of electrical power to the CVR or FDR, the

Safety Board issued Safety Recommendation A-99-16,31 which asked the FAA to do the

following:

Require retrofit after January 1, 2005, of all CVRs on all airplanes required to

carry both a CVR and an FDR with a CVR that...is capable of recording the last 2

hours of audio, and...is fitted with an independent power source that is located

with the digital CVR and that automatically engages and provides 10 minutes of

operation whenever aircraft power to the recorder ceases, either by normal

shutdown or by a loss of power to the bus.

The safety recommendation letter cited the investigation of the September 2, 1998,

Swissair flight 111 accident, which was conducted by the Transportation Safety Board of

Canada (TSB) with the participation of the Safety Board,32 as the most recent

investigation that had been “severely hampered” by the lack of critical flight information

and noted that “Since 1983, there have been 52 accidents and incidents in which

30 When the engine power levers are moved from the low-speed range to a higher speed range, power is

automatically removed from the low-rpm relays, the low-rpm buttons are automatically released, and the

CVR transitions to electrical power from the engine alternators. Most turbopropeller airplanes have

battery-operated CVR systems and are not equipped with circuitry like that installed on the accident

airplane.

31 In 1999, Safety Recommendation A-99-16 was placed on the Safety Board’s List of Most Wanted

Transportation Safety Improvements. For more information about Safety Recommendation A-99-16 and the

Most Wanted list, see the Board’s Web site at <http://www.ntsb.gov>.

32 In accordance with the provisions of Annex 13 to the Convention on International Civil Aviation, the

Safety Board participated in the TSB’s investigation as the representative of the State of Design and

Manufacture.
Factual Information 17 Aircraft Accident Report

information from either the CVR or FDR or both were lost due to interruption of electrical

power following an engine or generator failure or crew action.” 

In a March 19, 1999, letter, the FAA stated that it would issue a notice of proposed

rulemaking (NPRM) to address Safety Recommendation A-99-16. In a July 21, 2001,

letter, the Safety Board stated that the FAA had made little progress to address the

recommendation since its issuance 2 years previously. Therefore, the Board classified

Safety Recommendation A-99-16 “Open—Unacceptable Response,” pending issuance of

an NPRM and expeditious issuance of a final rule. 

On February 28, 2005, the FAA published an NPRM titled, “Revisions to Cockpit

Voice Recorder and Digital Flight Data Recorder Regulations,” which proposed requiring

that all CVRs record a minimum of 2 hours of audio information. The NPRM stated that

all newly manufactured aircraft would be required to be equipped with a 2-hour CVR

within 2 years of the issuance of a final rule and that all existing aircraft would be required

to be retrofitted with a 2-hour CVR within 4 years of the issuance of the rule. The NPRM

also proposed a requirement to install a 10-minute independent power source for CVRs on

newly manufactured aircraft. 

In an April 29, 2005, letter, the Safety Board stated that it was pleased about the

FAA’s proposed actions to require 2-hour CVRs on all aircraft within 4 years. However,

the Board stated that it was disappointed that the proposed requirement to install a

10-minute independent CVR power source only applied to newly manufactured aircraft.

The Board suggested that the FAA require the installation of an independent CVR power

source on all aircraft within 4 years of the final rule. Safety Recommendation A-99-16

remains classified “Open—Unacceptable Response,” pending the suggested rule change. 

1.11.2 Flight Data Recorder

The accident airplane was equipped with a Honeywell model 980-4100 FDR,

serial number 7657 that used a magnetic tape as the recording medium. The FDR system

was designed to record six parameters.33

The FDR was sent to the Safety Board’s laboratory for readout and evaluation. The

FDR was found to be in good condition, and the data were extracted normally.

About 25 hours of data were recorded by the FDR, including data for the accident flight.

About 0047, the airplane’s electrical power was interrupted, which caused a momentary

dropout of the FDR data. The FDR stopped recording about 0049.

33 Turbine-powered, transport-category aircraft manufactured on or before October 11, 1991, are

required to be equipped with an FDR that records a minimum of 11 parameters in accordance with 14 CFR

121.344. However, the accident FDR only recorded six parameters. The six parameters recorded and

verified were time, airspeed, pressure altitude, vertical load factor, magnetic heading, and microphone

keying.
Factual Information 18 Aircraft Accident Report

1.11.3 Safety Recommendation A-00-30

On April 11, 2000, as a result of longstanding concerns about the loss of critical

flight recorder data, the Safety Board issued Safety Recommendation A-00-30, which

asked the FAA to do the following:

Require that all aircraft operated under...14 Code of Federal Regulations Part

121, 125, or 135 and currently required to be equipped with a cockpit voice

recorder (CVR) and digital flight data recorder (DFDR) be retrofitted by

January 1, 2005, with a crash-protected cockpit image recording system.[34] The

cockpit image recorder system should have a 2-hour recording duration, as a

minimum, and be capable of recording, in color, a view of the entire cockpit

including each control position and each action (such as display selections or

system activations) taken by people in the cockpit. The recording of these video

images should be at a frame rate and resolution sufficient for capturing such

actions. The cockpit image recorder should be mounted in the aft portion of the

aircraft for maximum survivability and should be equipped with an independent

auxiliary power supply that automatically engages and provides 10 minutes of

operation whenever aircraft power to the cockpit image recorder and associated

cockpit camera system ceases, either by normal shutdown or by a loss of power to

the bus. The circuit breaker for the cockpit image recorder system, as well as the

circuit breakers for the CVR and the DFDR, should not be accessible to the flight

crew during flight.

In a March 29, 2004, letter, the FAA stated that flight recorder-related safety

recommendations continued to be difficult to respond to in a manner that the Safety Board

would find acceptable. The FAA also stated that flight recorder-related safety

recommendations presented unique challenges, including difficulties in cost/benefit

analysis, technical hurdles, retrofit problems, data use issues, and privacy concerns. 

On June 3, 2004, FAA and Safety Board staff met to discuss previously issued

flight recorder-related safety recommendations, including Safety Recommendation

A-00-30. In a December 15, 2004, letter, the Safety Board noted that, although the

meeting was constructive, the substance of the safety recommendations and the FAA’s

planned actions in response to them were not discussed; therefore, the Board classified

Safety Recommendation A-00-30 “Open—Unacceptable Response.” 

In its April 29, 2005, response to the February 2005 flight recorder-related NPRM,

the Safety Board stated that it was disappointed that the FAA had not addressed image

recorders in the NPRM. The Board also stated that image recorders would have provided

in-depth information about the facts, conditions, and circumstances surrounding numerous

accidents. The Board restated its opinion that image recorders could play a key role in

accident investigations by providing critical human performance and cockpit environment

information that would otherwise be unavailable. The Board encouraged the FAA to move

34 Image recorders obtain audio information (similar to that recorded by CVRs), event data (similar to

that recorded by FDRs), and information about the environment inside the cockpit and outside the cockpit

window. 
Factual Information 19 Aircraft Accident Report

quickly to implement Safety Recommendation A-00-30. On January 24, 2006, the Safety

Board reiterated Safety Recommendation A-00-30 as a result of its investigation of the

October 19, 2004, Corporate Airlines flight 5966 accident in Kirksville, Missouri.35

1.12 Wreckage and Impact Information

1.12.1 General Wreckage Description

The airplane initially impacted the top of a stand of trees, which exhibited a few

clean, angled cuts, about 40 feet agl. The airplane impacted the ground about 308 feet

north of the initial impact point. The airplane then impacted a grove of trees about 420 feet

from the initial impact point, where the aft fuselage came to rest, about 1.2 miles short of

the approach end of runway 36R. The forward fuselage was scattered about 200 feet

beyond the edge of the grove. The total wreckage path was about 600 feet long.

The forward half of the airplane and most of the wing structure were destroyed.

The airplane’s forward fuselage was found essentially split in half about a vertical plane

that extended from the nose to near the wing rear spar. The right half of the forward

fuselage remained partially attached to the rear fuselage but was severely damaged by

impact forces. Most of the left half of the forward fuselage was found severed from the

rest of the airplane and in several sections within the debris field. The section of the

fuselage from the wing rear spar to the tail, which included the inboard halves of both

horizontal stabilizers and the entire vertical stabilizer and rudder, was found intact,

oriented on about a 60° magnetic heading, and banked about 30° left wing down. The

forward portion of this section exhibited severe impact damage.

The right engine remained attached to the right wing and was found embedded in a

tree. The right propeller hub had separated from the engine and was found in the main

debris field. The left engine remained attached to the left wing and was found adjacent to

the cockpit at the forward end of the main debris field. The left propeller hub was found in

the main debris field. The compressor blades showed very little evidence of tip curling or

bending in the direction opposite of rotation. All of the turbine blades and nozzles were

found intact and showed no signs of metal spray. 

The engines were disassembled at Rolls-Royce’s facility in Indianapolis, Indiana,

under Safety Board direction. Examinations of both engines revealed no evidence of

uncontainment or burnthrough. Several compressor blades exhibited foreign object

damage on the trailing edges in the direction of engine rotation. Finely chopped or

pulverized green vegetative debris was found throughout both engines. The vegetative

debris showed no evidence of burning or charring. Pulverized dirt was found throughout

the left engine. The turbine blades and nozzles were intact on both engines; however, the

35 For more information about this accident, see National Transportation Safety Board, Collision with

Trees Short of the Runway, Corporate Airlines Flight 5966, British Aerospace BAE-J3201, N875KX,

Kirksville, Missouri, October 19, 2004, Aircraft Accident Report NTSB/AAR-06/01 (Washington, DC:

NTSB, 2006).
Factual Information 20 Aircraft Accident Report

left engine’s turbine vanes exhibited leading and/or trailing edge damage. No evidence of

any metal spray or splatter was found on any of the engines’ turbine blades.

The propellers were disassembled at PPI’s facility in Kent, Washington, under

Safety Board direction. Six of the eight propeller blade angles were measured to have been

from about 40° to 46° at the time of impact.36 Examinations revealed that one of the four

right propeller blades and three of the four left propeller blades had sheared off. All of the

fracture surfaces showed signatures consistent with overload, with no leading edge or

rotational damage. 

The airplane’s two batteries were found in the battery compartment on the

underside of the left wing, and both batteries exhibited substantial impact damage. The

ground proximity warning system (GPWS) unit, which is powered by the essential d.c.

electrical system, was found with the Mode 4 (flight into terrain when not in landing

configuration) warning button indicator activated.37

Four of the five cargo containers were destroyed by impact forces. The fifth

container was found intact in the aft fuselage section, and its base was deformed upward.

Three of the four forward cargo stops were found intact but separated from the floor

tracks. The fourth forward cargo stop was found attached to its floor track. The four aft

cargo stops were found intact and attached to their floor tracks. All of the recovered cargo

locks exhibited damage consistent with impact. 

1.12.2 Fuel Tank System Components and Controls

Both fuel cap access doors were found closed and latched. Both fuel filler caps

were found unlocked and were able to be lifted away without any counter-clockwise

rotation.38 The operating mechanism for the left fuel filler cap exhibited wear. A

functional check was performed on the left fuel filler cap, and, during several attempts to

engage, several complete clockwise turns were required to lock the cap in place. When the

cap was successfully engaged, very little counter-clockwise pressure was required to

loosen the cap. A functional check was performed on the right fuel filler cap, and it

operated normally. 

After the accident, Air Tahoma inspected the condition and installation of the fuel

filler caps on its other Convair airplanes, and no discrepancies were noted. In its July 2005

submission, Air Tahoma indicated that, after the accident, all company mechanics and Air

Tahoma-contracted fuel vendors were trained on over-wing fuel filler cap installation and

fueling procedures. Air Tahoma indicated that the company instructed flight

36 Two of the blades’ angles could not be determined because of accident damage.

37 If a warning mode activates in flight, one of five warning mode button indicators on the annunciator

panel will change from black to green and yellow. If power to the GPWS is lost, the warning button

indication will remain visible. 

38 Fuel filler caps are removed during fueling operations. Normal engagement of the fuel filler cap

requires the cap to be rotated about a quarter turn clockwise to lock into place securely. 
Factual Information 21 Aircraft Accident Report

crewmembers to ensure that the proper type and amount of fuel was added and that, during

preflight inspections and at intermediate stops, the fuel filler caps were secure.

The fuel boost pump low and primary fuel failure warning circuit breakers were

found open. The left fuel boost pump circuit breaker was found open, and the right fuel

boost pump circuit breaker was found closed.39

Impact damage precluded a continuity check between the fuel tanks and the

crossfeed lines. The left and right main fuel tank shutoff valve switches and the left and

right crossfeed valves were found in the open position. The emergency power-off switch

guard was broken off, and the switch was found in the off position. 

The left fuel quantity indicator was found indicating 0 lb of fuel. The right fuel

quantity indicator’s glass face was broken, and the fuel quantity indicator was found

indicating about 5,600 lbs of fuel. According to Kelowna Flightcraft, the Convair 580 type

certificate holder, the fuel quantity indication in the cockpit can indicate a fuel quantity

that is from 300 to 500 gallons greater than the actual amount, depending on the airplane’s

roll attitude.

The signed load manifest showed that the accident airplane had about 8,000 lbs of

fuel on board at takeoff.40 The manifest showed a fuel burn of about 4,200 lbs, which

would have left about 3,800 lbs of fuel on board at the time of impact. Air Tahoma

provided the Safety Board with the flight releases and fueling records for the accident

airplane’s 12 previous flights from MEM to CVG. Using fuel data from these records,

Board investigators calculated that the fuel burn for the accident airplane’s last 12 flights

ranged from about 3,500 to 4,200 lbs. 

1.13 Medical and Pathological Information

Fluid specimens obtained from the pilot and fluid and tissue specimens from the

first officer were transported to the FAA’s Civil Aerospace Medical Institute for

toxicological analysis. The specimens tested negative for alcohol and a wide range of

drugs, including major drugs of abuse.41

1.14 Fire

No evidence of an in-flight or a postcrash fire was found. 

39 For information about postaccident examinations and bench tests of the accident fuel boost pumps, 

see section 1.16.1.1. 

40 A copy of an Aircraft Service International Group aircraft service record indicated that, on the day of

the accident, company ground personnel added 3,564 lbs of fuel to the accident airplane’s fuel tanks.

41 The drugs tested in the postaccident analysis include (but are not limited to) marijuana, cocaine,

opiates, phencyclidine, amphetamines, benzodiazapines, barbiturates, antidepressants, antihistamines,

meprobamate, and methaqualone. 
Factual Information 22 Aircraft Accident Report

1.15 Survival Aspects

According to the Boone County Coroner’s Office autopsy report, the cause of

death for the first officer was “massive acute body trauma.” According to the captain’s

medical records, he sustained minor injuries, including multiple lacerations, acute right

lower extremity contusions, and acute bilateral forearm contusions.

1.16 Tests and Research

1.16.1 November 2004 Fuel Boost Pump Examinations

and Testing

On November 16 and 17, 2004, the fuel boost pump assemblies were examined

and bench tests were conducted at Canadian Aero Accessories Ltd.’s facility in Calgary,

Alberta, Canada, under Safety Board supervision. The exterior and the interior

components of the left electrically driven fuel boost pump and respective electric pump

motor exhibited no signs of damage or wear. The cooling fan on the pump motor was

clean, with no visible damage. The pump motor cooling fan could be rotated by hand with

no binding. The pump motor operated normally when power was applied. 

The top and front of the right fuel boost pump assembly exhibited some damage.

The internal components of the right fuel pump exhibited no signs of damage or wear. The

pump motor cooling fan cover and the fan blade directly beneath the dented portion of the

cover were found bent inward. None of the other fan blades exhibited damage, nor were

any rotational markings found. The pump motor cooling fan could be rotated by hand with

little resistance, and the pump motor operated normally when power was applied. 

During the bench tests, the left fuel boost pump was determined to be operable

within the manufacturer’s delivery specifications and maintained an output pressure of

20 psi. The right fuel boost pump was initially found to have an output pressure of 15 psi,

which was allowed by the issuance of PJCB 10-21.42 The output pressure setting screw

was then adjusted to the manufacturer’s delivery specifications; at which point, the right

fuel boost pump maintained an output pressure of 20 psi. Air Tahoma indicated that the

left and right fuel boost pump output pressures were not measured or altered after the

company bought the airplane in 2004. 

1.16.2 April 2005 Fuel Boost Pump Testing

On April 12 and 13, 2005, bench tests using the accident airplane’s right fuel boost

pump were conducted at Argo-Tech Corporation’s facility in Cleveland, Ohio. The fuel

boost pump tests simulated crossfeed operation from the left fuel tank, through a

42 Initially, Safety Board investigators and Convair 580 maintenance personnel thought that the 15-psi

output pressure setting had resulted from the impact.
Factual Information 23 Aircraft Accident Report

nonoperating right fuel boost pump and an open right fuel tank shutoff valve, consistent

with the airplane’s approximate fuel system configuration during the last portion of the

accident flight. The tests revealed that, with the left fuel boost pump output pressure set at

21 psi, the right engine’s fuel tank shutoff valve open, and both fuel crossfeed valves open,

the fuel not consumed by the right engine was allowed to flow back through the right fuel

boost pump and into the right fuel tank. 

1.17 Organizational and Management Information

Air Tahoma began Part 121 cargo operations on May 21, 1997. At the time of the

accident, Air Tahoma had 50 employees, including 15 pilots and a fleet of four

Convair 240 and four Convair 580 airplanes. The company operated cargo flights daily

from MEM; Cleveland and Columbus, Ohio; and Pittsburgh, Pennsylvania, to CVG. 

1.17.1 Flight Paperwork Procedures 

Air Tahoma’s FAA-approved General Operations Manual (GOM), Section 1.617,

“Disposition of Documents,” stated, in part, the following:

If a flight originates at a place other than the Principal Operations Base, the

Captain will fax a copy of Flight Release and the weight and balance manifest to

the company...If the aircraft departs a station where there is a person authorized

by the Company who manages the departure, and who does not depart on the

aircraft, then that person or the crew may retain the signed copies of the required

documents in a designated location. 

Air Tahoma’s GOM, Section 1.741, “Preflight Procedures,” stated that a flight plan

form, which is incorporated in the flight release form, must be completed by the flight

crew before a company aircraft departs for a flight or series of flights. The GOM stated

that weight and balance calculations for the flight plan form “will be computed on an

approved weight and balance form” and added the following

The completed [form] will be attached to both copies of the flight release

form...A copy of the Flight Release...and Weight and Balance form...will be

faxed, or mailed to [Air Tahoma] Operations. If there is no fax available

then...self-addressed envelopes...can be used. The envelope will be given to the

FBO [fixed-base operator] to be mailed if there is no mailbox available. 

1.17.2 Air Tahoma Fuel Crossfeed Procedures

Air Tahoma’s CV-580 Quick Reference Handbook (QRH), dated February 5,

1997, contains fuel crossfeed procedures, which state, in part, the following:

CROSSFEED FROM EITHER TANK TO OPPOSITE ENGINE

1 BOTH FUEL BOOST PUMPS.......................................................................ON
Factual Information 24 Aircraft Accident Report

2 BOTH AIRCRAFT FUEL BOOST PRESSURE LIGHTS .......................... OFF

3 CROSSFEED VALVE................................................................................ OPEN

4 FUEL BOOST PUMP FOR TANK NOT TO BE USED ............................. OFF

IF EITHER OR BOTH AIRCRAFT FUEL BOOST PRESSURE LIGHTS

ARE ILLUMINATED:

• BOTH FUEL BOOST PUMPS.......................................................................ON

• RESET AS REQUIRED

CROSSFEED VALVE C/B [CIRCUIT BREAKER] (OVERHEAD PANEL)

• FUEL SHUT OFF VALVE C/B

• FUEL BOOST PUMP C/B

• FUEL BOOST PUMP FOR TANK NOT TO BE USED ............................. OFF

IF EITHER OR BOTH AIRCRAFT FUEL BOOST PRESSURE LIGHTS

ARE ILLUMINATED:

• AIRCRAFT BOOST PUMPS .................................................................AS REQ

• CROSSFEED VALVE........................................................................... CLOSED

• DO NOT CROSSFEED

• END

5 TANK SHUTOFF VALVE FOR TANK NOT USED................................... OFF

During postaccident interviews, the captain stated that he had previously

performed fuel crossfeed operations about 5 to 10 times in the Convair 580. The captain

stated that fuel crossfeed operations were always performed to correct an in-flight fuel

imbalance. The captain stated that Air Tahoma trained company pilots to use the QRH

during fuel crossfeed operations.43

According to the company’s chief pilot, pilots were trained to crossfeed fuel only

in safety-of-flight situations. He stated that, because the company typically operated short

flights, from 1 to 1.5 hours long, any in-flight fuel imbalance could be corrected during

ground fueling operations.44 Interviews of other company pilots revealed that they did not

routinely crossfeed fuel in flight. However, a Safety Board review of Air Tahoma’s

operations and training manuals revealed that the company had no written documentation

regarding fuel crossfeed operations restrictions.

43 A company ground school instructor indicated that, because the captain attended the reduced training

course, he received “more of a review” of the fuel crossfeed operations procedures. 

44 Kelowna Flightcraft indicated that it also had a policy to restrict fuel crossfeed operations to

safety-of-flight situations because the company only operated short flights.
Factual Information 25 Aircraft Accident Report

The captain stated that he thought that the fuel tank shutoff valve should not be

turned off during fuel crossfeed operations because, if the shutoff valve could not be

reopened, the fuel in that tank would not be accessible. The captain thought that his two

previous employers did not require that the fuel tank shutoff valve be closed during fuel

crossfeed operations.45 The captain also thought that the Convair 580 had a one-way check

valve that would prevent fuel from transferring from one tank to another tank during

crossfeed operations.46

Postaccident interviews with Air Tahoma’s chief pilot and Nolinor Aviation

personnel revealed that additional pilots believed that the Convair 580 fuel tank shutoff

valve had a tendency to fail. Further, a Kelowna Flightcraft maintenance instructor stated

that, during company training, he had been asked about fuel tank shutoff valve failures. He

believed that this concern led many pilots to leave the fuel tank shutoff valve open. The

instructor stated that he thought that the pilots’ concerns were unfounded because, in the

previous 10 years, no customers had reported any fuel tank shutoff valve failures.47

1.17.2.1 Airplane Manufacturer Fuel Crossfeed Procedures

The airplane manufacturer’s AFM contains the following fuel crossfeed procedures: 

(1) place boost pump switch for tank being used to the ON position and place the

crossfeed switch to the ON position, (2) place the boost pump switch for the

tank not being used to the OFF position, and (3) place the fuel shutoff valve

switch for the tank not being used to the CLOSED position. 

As noted previously, the procedures also contain a caution stating that transferring

fuel from one tank to the other is prohibited because structural failure or overflow of fuel

through the vent system could occur. 

1.17.2.2 Nolinor Aviation Fuel Crossfeed Procedures

Nolinor Aviation, one of the captain’s previous employers, operated five

Convair 580 airplanes, none of which had a one-way fuel check valve installed in the fuel

system. At the time of the accident, Nolinor Aviation’s fuel crossfeed operations

procedures, which were contained in the company’s FOM (dated February 14, 1998),

included a step indicating that the fuel tank shutoff valve on the tank not being used

should be closed, “subject to the captain’s discretion.” The company’s QRH did not

45 The investigation revealed that one of the captain’s previous employers, Nolinor Aviation, did not

require that the fuel tank shutoff valve be closed during crossfeed operations. For additional information

about Nolinor Aviation’s fuel crossfeed procedures, see section 1.17.2.2.

46 One-way check valves are not typically installed on airplanes, and the accident airplane did not have

one installed. According to a Kelowna Flightcraft representative, one Convair 580 operator modified its fleet

of about 30 Convair 580 airplanes in the 1960s under an engineering order by installing a one-way check

valve, which prevented fuel from flowing back into the fuel tanks when the fuel tank shutoff valve was left

open. However, the representative stated that this operator was no longer in business and that its airplanes

had represented a small percentage of the entire Convair 580 fleet.

47 Further, a search of the FAA’s service difficulty reports (SDR) database revealed no history of

Convair 580 fuel tank shutoff valve failures.
Factual Information 26 Aircraft Accident Report

include this remark. According to Nolinor Aviation’s chief pilot, in November 2004, the

company corrected the discrepancy between its QRH and FOM by removing the remark,

“subject to the captain’s discretion,” from the fuel crossfeed operations procedures

contained in the FOM.

1.17.3 Air Tahoma Engine Flameout Procedures 

The Air Tahoma CV-580 QRH contains emergency flameout procedures (loss of

one or both engines), which state, in part, the following:

1. AIRSPEED........................................................................ MAINTAIN 170 KTS

IF RPM 5500-6500 RPM:

POWER LEVER(S)1” [INCH] ABOVE FLIGHT IDLE

FUEL VALVES........................................................................................ CAPPED

FUEL BOOST PUMPS ..................................................................................... ON

FEATHER BUTTON.....................................PUSH TO 2500 RPM, THEN PULL

PRIMER......................................................................HOLD UNTIL LIGHT OFF

E-HANDLE ....................................................................... IDENTIFY & GUARD

When the accident airplane was about 4.5 miles from the runway and at an altitude

of about 2,300 feet,48 the flight crew reported to the CVG ATCT that they were having

engine problems. During postaccident interviews, the captain could not remember if the

airplane had experienced an engine problem or whether he had performed any emergency

or abnormal procedures during the accident flight. 

1.17.4 Postaccident Actions

On August 26, 2004, Air Tahoma issued Operations Memorandum 2 to all flight

crewmembers to reemphasize which procedures to follow during fuel crossfeed

operations. The memorandum stated, in part, that crossfeeding should only be conducted

if it is necessary for the safety of flight; the QRH should be used during crossfeeding; a

checklist should be placed in the throttle quadrant as a reminder that fuel crossfeeding was

in progress; instruments should not be blocked by checklists; and crew resource

management must be practiced and communications forceful, if necessary. Air Tahoma

also stated that its captains had been instructed to physically touch the fuel panel when it is

48 The terrain height in the accident area was about 900 feet.
Factual Information 27 Aircraft Accident Report

called on the checklist rather that just looking at it.49 In addition, Air Tahoma installed a

breakaway wire on all of its Convair 580 fuel tank shutoff and crossfeed valve

cover-guarded switches.50

Further, Air Tahoma stated that it had installed captain-side, overhead red lights,

which indicate the position of the fuel crossfeed and fuel tank shutoff valve switches.

When the left and/or right fuel tank shutoff valve switches are in the off (closed) position,

the respective lights will illuminate, and when the fuel crossfeed valve switch is in the on

(open) position, the respective light will illuminate. During normal operations, the fuel

tank shutoff valve switches are on and the fuel crossfeed valve switch is off, resulting in

all three lights being extinguished. Air Tahoma noted that the lights indicate crossfeed or

fuel tank shutoff valve switch position not operation status. 

1.18 Additional Information

1.18.1 Previous Convair 580 In-Flight Fuel Imbalance Incident

On September 21, 2004, a Nolinor Aviation Convair 580 had to return to its

departure airport in Montreal, Canada, because of a fuel imbalance. The incident flight

crew stated that, shortly after takeoff, a flight attendant reported that a passenger had seen

fuel coming out of the right wing. The flight crew reported that, about this time, they

needed to move the aileron to the left to maintain level flight, which required about a

10°-left input on the control wheel, and the fuel quantity indicators showed that the left

and right fuel tanks had 4,000 and 6,000 lbs of fuel, respectively.51 The flight crew stated

that at this point, they noticed that the fuel crossfeed valve was open. The flight crew

closed the fuel crossfeed valve and decided to return to Montreal, where they landed

safely. The flight crew stated that the airplane was controllable at all times and that the

fuel imbalance did not exceed the in-flight limit of 2,080 lbs.

Ground maintenance personnel determined that no fuel was coming out of the

airplane’s wing; however, it appeared that some fuel had been pumped overboard through

the fuel vent system. The maintenance personnel also determined that the right and left

fuel boost pumps had output pressure settings of 15 and 21 psi, respectively.52 According

to Nolinor Aviation, the left fuel boost pump had been replaced before the incident flight.

49 Operations Memorandum 2 also stated that, if excessive trim is needed to maintain normal flight, a

problem might exist. Air Tahoma’s chief pilot stated that the company did not have any training procedures

related to control wheel imbalance but that he expected pilots to actively troubleshoot such a problem and to

consider fuel imbalance as a possible cause. 

50 A breakaway wire is a device that supplements a cover-guarded switch and passively warns pilots

that using the fuel switches in flight is nonroutine. If a flight crew used the breakaway wire in flight,

maintenance personnel would have to replace it.

51 According to Nolinor Aviation’s chief pilot, the incident airplane was fueled to 11,200 lbs before

takeoff. 

52 Nolinor Aviation indicated that it normally operated company airplanes with a fuel boost pump

output pressure setting of 15 psi.
Factual Information 28 Aircraft Accident Report

Nolinor indicated that company maintenance personnel did not bench check the

replacement fuel boost pump before installing it on the airplane; therefore, the company

did not know that the airplane was operating with different fuel boost pump output

pressure settings. In addition, the maintenance personnel left the fuel crossfeed valve open

after performing postinstallation checks on the left fuel boost pump.
29 Aircraft Accident Report

2. Analysis

2.1 General

The captain and first officer were properly certificated and qualified under Federal

regulations. 

No evidence indicated that flight crew fatigue was a factor in this accident, and no

evidence indicated any preexisting medical or behavioral conditions that might have

affected the accident flight.

The airplane was properly maintained in accordance with Federal regulations and

approved company procedures.

The recovered components showed no evidence of any preexisting powerplant,

system, or structural failures. No evidence indicated that any of the airplane’s cargo

shifted during the flight.

Neither the weather nor the inoperative DME on the CVG VOR was a factor in

this accident.

A review of the preflight fueling log, the signed load manifest found at the

accident site, and previous flight information for the accident airplane revealed that there

was sufficient fuel on board the airplane for the flight from MEM to CVG.

This analysis discusses the captain’s preflight actions and the accident sequence,

including the role of the flight crew’s performance. This analysis also discusses the Convair

580 fuel system, including fuel crossfeed operations; the dual engine power loss; operating

with different fuel boost pump output pressure settings; and independent CVR power sources.

2.2 The Captain’s Preflight Actions

Air Tahoma’s procedures and Federal regulations require that a flight crewmember

prepare, complete, and leave a copy of the load manifest at the departure station. The

captain did not leave a copy of the load manifest for the accident flight at MEM. However,

two load manifests, one signed by the captain and the other unsigned, were found at the

accident site. 

A review of the unsigned load manifest and CVR transcript information revealed

that, during manual, preflight weight and balance calculations,53 the captain used the

53 As mentioned previously, the captain had to manually complete the weight and balance calculations

before takeoff because the handheld computer typically used by Air Tahoma’s pilots to make these

calculations was not working. 
Analysis 30 Aircraft Accident Report

incorrect fuel burn moment value (1,067 instead of 1,667).54 Because of this error, the

captain’s calculations showed the airplane outside of acceptable weight and balance limits.

The captain stated during postaccident interviews that, although his preflight calculations

showed the airplane outside of weight and balance takeoff limits, he used his “general

experience” (for example, he stated that he looked at the nose landing gear strut extension)

to determine that the airplane was within limits. On the basis of his observations, he

decided to take off and finish the weight and balance paperwork during the flight. 

A review of the signed load manifest and CVR transcript information revealed that

the captain used the correct fuel burn moment value (1,667) on this manifest. The

captain’s calculations using the correct moment value indicated that the airplane was

within acceptable weight and balance limits. Safety Board investigators verified the

captain’s recalculations. The Safety Board concludes that the captain’s preflight weight

and balance calculations indicated that the airplane was not within takeoff limits;

therefore, he should not have allowed the airplane to take off. However, the captain’s

calculations were incorrect, and the airplane’s weight and balance were within limits.

2.3 Accident Sequence

The accident flight departed MEM about 2329. Postaccident interviews with the

captain and an examination of FDR data indicated that the takeoff, climb, and cruise

portions of the flight (up to the time that the CVR transcript started) were uneventful.

At 0017:49, the captain told the first officer that he was going to “balance out the fuel,”55

and the first officer acknowledged. 

At 0026:30, the captain told the first officer that he had been working on the

weight and balance calculations since departing MEM. At 0032:31 (about 15 minutes after

initiating the fuel crossfeed operations), the captain stated that he was finishing up the

weight and balance calculations. Two minutes later, he stated, “okay, back with you here.”

During postaccident interviews, the captain stated that, because he was busy calculating

the airplane’s weight and balance, he was “preoccupied” and “stressed” during the flight.

Although the weight and balance calculations were not difficult, because the captain used

the incorrect fuel burn moment value, the calculations were not computing correctly, and

the captain became preoccupied with trying to identify the mistake.

From 0038:22 to 0044:16, the first officer repeatedly told the captain that the

airplane was not handling well. Specifically, he stated numerous times that the control

wheel was requiring a “lot of force.” The captain did not respond to the first officer’s first

five comments regarding the airplane’s unusual handling characteristics, which occurred

over a period of less than 6 minutes. The captain did not request clarification or

elaboration from the first officer nor did he initiate any troubleshooting or take over the

54 The fuel burn moment value appeared to have been written as 1,067 and then rewritten as 1,667. The

captain used an estimated fuel burn of 4,200 lbs in his calculations. The correct fuel burn moment value for

a fuel burn of 4,200 lbs is 1,667.

55 Fuel crossfeed operations are used to balance out the fuel in an airplane’s fuel tanks.
Analysis 31 Aircraft Accident Report

flight controls to independently validate the first officer’s observations; instead, the

captain remained silent, changed the subject, or was distracted by normal flight

communications. At 0044:32, the captain finally responded to the first officer by telling

him that they would perform a “full control check on the ground.” 

The PIC has final command authority in the cockpit and is responsible for the

safety of the flight. It is reasonable to expect that, as part of the command responsibilities,

the PIC would promptly investigate a potential flight control system anomaly reported by

another flight crewmember. Unusual changes in an airplane’s handling characteristics can

possibly affect the safety of flight. Typically, one of the first actions taken to determine the

cause of an airplane’s changing handling characteristics would be to check for a possible

fuel imbalance. Because the captain did not respond promptly to the first officer’s

comments, he missed several opportunities to recognize that the airplane’s fuel was

imbalanced. The Safety Board concludes that the captain did not recognize the importance

of the cues provided by the first officer, and he failed to perform expected PIC duties.

At 0045:37, shortly after the airplane passed through 3,200 feet, the captain started

the in-range checklist, which includes a step to check the fuel tank shutoff and crossfeed

valve switch positions. Air Tahoma’s FOM indicates that the in-range checklist should be

started before leaving 12,000 feet and that “early completion [of the checklist] will

minimize cockpit distractions.” Therefore, the captain should have started the in-range

checklist about 14 minutes earlier (shortly before 0035; at which time, the airplane was at

an altitude of about 12,000 feet, and the first officer had not yet stated his concerns about

the airplane’s unusual handling characteristics). 

While performing the in-range checklist, the captain stated that they had an

“imbalance on this...crossfeed I left open.” This was the only comment recorded by the

CVR regarding fuel crossfeed operations since the captain started the operation almost

30 minutes earlier. Further, the CVR did not record any comments by either flight

crewmember indicating that they were monitoring the airplane’s fuel quantity. If the flight

crewmembers had been monitoring the gauges, they would have seen unmistakable

indications of a developing fuel imbalance. The fuel imbalance developed over a

30-minute period, and, as noted, during that time, the pilots had several opportunities to

recognize and correct the problem; however, they failed to do so. 

The Safety Board concludes that the captain was preoccupied with the weight and

balance calculations during critical portions of the flight and, as a result, he did not

monitor the fuel crossfeed operations, which resulted in a fuel imbalance and unusual

airplane handling characteristics. The Safety Board further concludes that the flight crew

did not monitor the fuel quantity gauges or respond properly to the airplane’s changing

handling characteristics, and the captain did not start the in-range checklist at the

appropriate altitude; as a result, the crew missed several opportunities to identify the

ongoing fuel crossfeed operations and determine that the airplane’s fuel was imbalanced.

At 0046:35, the first officer stated, “we’re gonna flame out.” The captain

responded, “I got the crossfeed open.” The first officer then stated, “we’re losing power,”

and, “we’ve lost both of them [engines].” The captain replied, “nope.” The CVR stopped
Analysis 32 Aircraft Accident Report

recording at 0046:55, and, about the same time, a momentary interruption in electrical

power occurred. About 2 minutes later, the FDR stopped recording. Although Air

Tahoma’s QRH contained engine flameout procedures, the pilots most likely would not

have had sufficient time or altitude to restart the engines because they lost power during

short final approach. 

2.4 Convair 580 Fuel Crossfeed Operations

The Convair 580 type certificate data sheet and Air Tahoma’s FOM prohibit fuel

transfer from one tank to the other while the airplane is on the ground or in flight. The type

certificate data sheet also states, “When operating with the crossfeed system, turn off fuel

valve for tank not being used,” which would preclude fuel transfer. The AFM also

prohibits the transfer of fuel from one tank to the other and cautions, “to do so might build

up excessive pressure in a tank, which could result in structural failure or cause fuel to

overflow through the vents.” 

Step 5 of Air Tahoma’s QRH fuel crossfeed procedures states that the fuel tank

shutoff valve for the fuel tank not being used must be closed during fuel crossfeed

operations. Further, the Convair 580’s overhead fuel panel has a placard on the bottom that

states the same thing. However, the captain stated that he did not shut off the right fuel

tank shutoff valve, and wreckage examinations confirmed that both the left and right fuel

tank shutoff valves were open at impact. Postaccident fuel boost pump testing revealed

that, in this configuration, all of the fuel from the left fuel tank not used by the engines

could transfer into the right fuel tank in a relatively short period of time. 

During postaccident interviews, the captain stated that he was aware of the step to

close the fuel tank shutoff valve for the tank not being used. However, the captain added

that he intentionally kept the valve open because he thought that Convair fuel tank shutoff

valves tended to fail after being shut off, preventing the use of the fuel in the closed tank.56

The captain also stated that a previous employer (Nolinor Aviation) allowed company

pilots to decide whether or not to close the valve.57 The Safety Board is concerned that

Convair 580 pilots’ mistaken belief that the fuel tank shutoff valves have a tendency to fail

may cause these pilots to intentionally keep the fuel tank shutoff valves open during fuel

crossfeed operations, which could allow fuel to transfer and cause either structural damage

or fuel overflow.

The Safety Board concludes that, although fuel transfer is prohibited on the

Convair 580 airplane, fuel transfer can occur during fuel crossfeed operations if the fuel

tank shutoff valve for the tank not being used is left open. The Safety Board further

56 During postaccident interviews, other Convair 580 pilots indicated that they also thought that

Convair fuel tank shutoff valves tended to fail. However, manufacturer and FAA SDR data did not indicate a

history of Convair fuel tank shutoff valve failures.

57 At the time of the accident, Nolinor Aviation’s FOM stated that the fuel tank valve on the tank to be

shut off should be closed, “subject to the captain’s discretion.” After the accident, Nolinor removed this

remark from the crossfeed procedures contained in its FOM. 
Analysis 33 Aircraft Accident Report

concludes that all of the fuel from the airplane’s left tank that was not used by the engines

transferred into the right tank because the captain intentionally kept the right fuel tank

shutoff valve open during fuel crossfeed operations, which was not in accordance with

approved fuel crossfeed procedures. Therefore, to prevent similar accidents from

occurring in the future, the Safety Board believes that the FAA should issue a flight

standards information bulletin to all principal operations inspectors of Convair 580

operators that familiarizes operators with the circumstances of the Air Tahoma flight 185

accident, including the importance of closing the fuel tank shutoff valve for the tank not

being used during fuel crossfeed operations.

2.5 Dual Engine Power Loss

The Safety Board considered why both engines lost power even though the right

fuel tank had sufficient fuel for operation. Further, after the engines failed, the flight crew

was still able to make transmissions to ATC, the GPWS alerted, and the FDR continued to

record, indicating that the airplane still had partial electrical power. 

Wreckage examinations indicated that, when the left fuel tank was exhausted of

fuel, the left fuel boost pump most likely continued to operate, which allowed air to enter

the fuel system and reduced the fuel pressure to the left and right engine-driven fuel pump

inlets. If the captain had turned on the right fuel boost pump after he identified that he had

left the crossfeed valve switch open, it is possible that the right engine would have

received sufficient fuel pressure to continue to operate; however, there is no evidence that

he did so. Specifically, the right fuel boost pump fan motor cooling fan cover and the

blade directly beneath the cover were found bent inward, and no rotational markings were

found, indicating that the right fuel boost pump was not operating at the time of impact.

Postaccident testing of the left and right fuel pumps revealed no evidence of preexisting

failures.

The Safety Board concludes that, during the airplane’s descent to landing, the fuel

in the left fuel tank, which was providing fuel to both engines, was exhausted because

both engine-driven fuel pumps drew air from the left tank into the fuel system instead of

fuel from the right tank, resulting in a dual-engine flameout.

2.6 Differential Fuel Boost Pump Output

Pressures Settings

PJCB 10-21, “Aircraft Fuel Boost Pump Output Pressure Limit-Reduce,” which

was published in October 1969, provided details on an optional procedure that allowed

Convair 580 operators to reduce the typical fuel boost pump output pressure setting of

21 psi to 15 psi to “improve the service life of the aircraft fuel boost pump.” The bulletin

stated that, although an aircraft could be operated with different boost pump output

pressure settings, “preferably, aircraft should be operated with identical boost pump
Analysis 34 Aircraft Accident Report

pressure settings.” Postaccident testing of the accident fuel boost pumps revealed that the

left and right fuel boost pumps had output pressure settings of 20 and 15 psi, respectively. 

Air Tahoma maintenance personnel reported that they were not aware of

PJCB 10-21 or the provision to lower the fuel boost pump output pressure setting to

15 psi. In June 2004, Air Tahoma replaced the left fuel boost pump on the accident

airplane with a pump that had an output pressure setting of 21 psi. However, Air Tahoma

did not replace the right fuel boost pump and did not measure or alter the output pressure

setting. As a result, Air Tahoma was unaware that it was operating the airplane with

different left and right fuel boost pump output pressure settings. The Safety Board is

concerned that other Convair 580 operators may not be aware of PJCB 10-21 and its

provision to allow fuel boost pumps to be set at different output pressure settings. 

On September 21, 2004, a Nolinor Aviation Convair 580 experienced an in-flight

fuel imbalance. The incident flight crew reported that a passenger had seen fuel coming

from the right wing and that, about the same time, the fuel quantity indicators showed that

the left and right fuel tanks had 4,000 and 6,000 lbs of fuel, respectively. The flight crew

closed the fuel crossfeed valve after noticing that the valve was open. Nolinor Aviation

ground maintenance personnel determined that the right and left fuel boost pumps had

output pressure settings of 15 and 21 psi, respectively, and that the crossfeed valves had

been left open, which allowed fuel to transfer from the left to the right fuel tank. Nolinor

Aviation indicated that the incident airplane’s left fuel boost pump had been replaced and

had not been bench checked before installation. As a result, the company was unaware

that the incident airplane’s left fuel boost pump was operating with an output pressure

setting of 21 psi. Nolinor Aviation indicated that it typically operated its Convair 580

airplanes with a fuel boost pump output pressure setting of 15 psi.

Kelowna Flightcraft, the Convair 580 type certificate holder, indicated that most

operators normally set the fuel boost pumps to the same output pressure settings.

However, the Safety Board is concerned that PJCB 10-21 allows Convair 580 airplanes to

operate with different output pressure settings. Further, given the age of the Convair 580

fleet, current operators might not have a complete history of the airplanes, including

possible changes made to the fuel boost pumps in accordance with PJCB 10-21. Although

operating the Convair 580 with different fuel boost pump output pressure settings does not

in itself create an unsafe operating condition, the Board notes that crossfeed valves are not

monitored58 and that the only indication that these valves are open is the switch position in

the cockpit. Such operation did not factor in the accident; however, the Nolinor Aviation

incident did reveal that, if an airplane operates with different fuel boost pump output

pressure settings and with the crossfeed valves unintentionally left open, a large amount of

fuel can transfer from one tank to another in a short period of time, possibly causing

structural failure or fuel overflow. 

The Safety Board concludes that fuel transfer can occur on the Convair 580

airplane if it is operated with different fuel boost pump output pressure settings and with

58 No positive indication, such as a light, exists in the cockpit to indicate whether the crossfeed system

is operating.
Analysis 35 Aircraft Accident Report

the fuel crossfeed valves unintentionally left open. Therefore, the Safety Board believes

that the FAA should require Convair 580 operators to set the left and right fuel boost pump

output pressure settings on their airplanes to the same setting.

2.7 Cockpit Voice and Image Recorder Requirements

As noted previously, whether the Convair 580’s CVR electrical relay circuitry

enables battery power to the CVR when the engines are in the low-speed range or shut

down (which can be caused by fuel exhaustion) depends on whether the flight crew pushes

in the low-rpm buttons located on the center pedestal. If the low-rpm button are pushed in

when the engines are in the low-speed range or shut down, the low-rpm relays are

energized, and the batteries provide power to the CVR. However, when both engines are

in the low-speed range or shut down and the low-rpm buttons are not pushed in, no power

is provided to the CVR. 

Although electrical relay circuitry is an effective method of powering the CVR

during ground operations, power to the CVR is compromised if both a.c. alternators are in

the low-speed range or shut down in flight and the pilots do not push in the low-rpm

buttons. Accordingly, the CVR on the accident airplane lost power when the airplane’s left

fuel tank was exhausted of fuel, both engines lost power, and the pilots did not push in the

low-rpm buttons. The Safety Board notes that the FDR, which did not require relay

circuitry to operate at lower power settings, received electrical power throughout the

entire accident sequence (except for the momentary dropout of power about 0047) and

operated normally until impact.

Even before this accident, the Safety Board had longstanding concerns about

accidents and incidents in which critical CVR information was lost because of an

electrical power interruption. As a result of its longstanding concerns about this issue and

its assistance in the TSB’s Swissair flight 111 accident investigation, the Board issued

Safety Recommendation A-99-16 to the FAA, which stated, in part, the following:

All airplanes required to carry both a CVR and an FDR [should be retrofitted]

with a CVR that...is fitted with an independent power source...that automatically

engages and provides 10 minutes of operation whenever aircraft power to the

recorder ceases, either by normal shutdown or by a loss of power to the bus.

The Safety Board is disappointed that the FAA’s February 28, 2005, NPRM,

“Revisions to Cockpit Voice Recorder and Digital Flight Data Recorder Regulations,”

only proposes requiring the installation of a 10-minute independent CVR power source on

newly manufactured aircraft. Therefore, in its comments on the NPRM, the Board

suggested requiring the installation of a 10-minute independent CVR power source on all

aircraft within 4 years of the issuance of a final rule. 

As a result of its investigation of the October 19, 2004, Corporate Airlines

flight 5966 accident and longstanding concerns about the loss of critical flight recorder
Analysis 36 Aircraft Accident Report

data, on January 24, 2006, the Safety Board reiterated Safety Recommendation A-00-30,

which asked the FAA, in part, to do the following: 

Require that all aircraft operated under...14 Code of Federal Regulations Part

121, 125, or 135 and currently required to be equipped with a [CVR] and [DFDR]

be retrofitted by January 1, 2005, with a crash-protected cockpit image recording

system. The cockpit image recorder system should have a 2-hour recording

duration...and be capable of recording, in color, a view of the entire cockpit

including each control position and each action (such as display selections or

system activations) taken by people in the cockpit. 

The FAA did not address cockpit image recorders in its February 2005 NPRM. In

its response to the NPRM, the Safety Board stated that it was disappointed that the FAA

had not addressed image recorders in the NPRM and restated its opinion that cockpit

image recorders could play a key role in accident investigations by providing critical

human performance and cockpit environment information that would otherwise be

unavailable. 

If the accident airplane had been equipped with a 10-minute independent power

source, the CVR would have recorded important information about the flight crew’s

actions after the loss of engine power until the airplane impacted the ground. Further, if

the airplane had been equipped with a cockpit image recorder, the recorder could have

provided additional critical human performance and cockpit environment information.

The Safety Board concludes that the accident investigation would have benefited from the

retrofit of an independent CVR power source and a cockpit image recorder. Because of its

continued concerns in this area, the Safety Board reiterates Safety

Recommendation A-99-16 and again urges the FAA to require the retrofit of all existing

aircraft required to carry both a CVR and an FDR with a CVR that is fitted with an

independent power source. Further, the Board again urges the FAA to quickly implement

Safety Recommendation A-00-30.
37 Aircraft Accident Report

3. Conclusions

3.1 Findings

1. The captain and first officer were properly certificated and qualified under Federal

regulations.

2. No evidence indicated that flight crew fatigue was a factor in this accident, and no

evidence indicated any preexisting medical or behavioral conditions that might have

affected the accident flight.

3. The airplane was properly maintained in accordance with Federal regulations and

approved company procedures.

4. The recovered components showed no evidence of any preexisting powerplant,

system, or structural failures. No evidence indicated that any of the airplane’s cargo

shifted during the flight.

5. Neither the weather nor the inoperative distance measuring equipment on the

Cincinnati/Northern Kentucky International Airport very high frequency

omnidirectional range was a factor in this accident.

6. Sufficient fuel was on board the airplane for the flight from Memphis International

Airport to Cincinnati/Northern Kentucky International Airport. 

7. The captain’s preflight weight and balance calculations indicated that the airplane was

not within takeoff limits; therefore, he should not have allowed the airplane to take

off. However, the captain’s calculations were incorrect, and the airplane’s weight and

balance were within limits.

8. The captain did not recognize the importance of the cues provided by the first officer,

and he failed to perform expected pilot-in-command duties.

9. The captain was preoccupied with the weight and balance calculations during critical

portions of the flight and, as a result, he did not monitor the fuel crossfeed operations,

which resulted in a fuel imbalance and unusual airplane handling characteristics.

10. The flight crew did not monitor the fuel quantity gauges or respond properly to the

airplane’s changing handling characteristics, and the captain did not start the in-range

checklist at the appropriate altitude; as a result, the crew missed several opportunities

to identify the ongoing fuel crossfeed operations and determine that the airplane’s fuel

was imbalanced. 
Conclusions 38 Aircraft Accident Report

11. Although fuel transfer is prohibited on the Convair 580 airplane, fuel transfer can

occur during fuel crossfeed operations if the fuel tank shutoff valve for the tank not

being used is left open. 

12. All of the fuel from the airplane’s left tank that was not used by the engines

transferred into the right tank because the captain intentionally kept the right fuel tank

shutoff valve open during fuel crossfeed operations, which was not in accordance

with approved fuel crossfeed procedures. 

13. During the airplane’s descent to landing, the fuel in the left fuel tank, which was

providing fuel to both engines, was exhausted because both engine-driven fuel pumps

drew air from the left tank into the fuel system instead of fuel from the right tank,

resulting in a dual-engine flameout.

14. Fuel transfer can occur on the Convair 580 airplane if it is operated with different fuel

boost pump output pressure settings and with the fuel crossfeed valves

unintentionally left open.

15. The accident investigation would have benefited from the retrofit of an independent

cockpit voice recorder power source and a cockpit image recorder.

3.2 Probable Cause

The National Transportation Safety Board determines that the probable cause of

this accident was fuel starvation resulting from the captain’s decision not to follow

approved fuel crossfeed procedures. Contributing to the accident were the captain's

inadequate preflight planning, his subsequent distraction during the flight, and his late

initiation of the in-range checklist. Further contributing to the accident was the flight

crew’s failure to monitor the fuel gauges and to recognize that the airplane’s changing

handling characteristics were caused by a fuel imbalance. 
39 Aircraft Accident Report

4. Recommendations

4.1 New Recommendations

As a result of its investigation of the August 13, 2004, Air Tahoma, Inc., flight 185

accident, the National Transportation Safety Board makes the following

recommendations:

To the Federal Aviation Administration:

Issue a flight standards information bulletin to all principal operations

inspectors of Convair 580 operators that familiarizes operators with the

circumstances of the Air Tahoma flight 185 accident, including the

importance of closing the fuel tank shutoff valve for the tank not being

used during fuel crossfeed operations. (A-06-39)

Require Convair 580 operators to set the left and right fuel boost pump

output pressure settings on their airplanes to the same setting. (A-06-40)

To Transport Canada:

Require Convair 580 operators to set the left and right fuel boost pump

output pressure settings on their airplanes to the same setting. (A-06-41)

4.2 Previously Issued Recommendation Being 

Reiterated in This Report

The Safety Board reiterates the following recommendation to the Federal Aviation

Administration:

Require retrofit after January 1, 2005, of all cockpit voice recorders (CVR)

on all airplanes required to carry both a CVR and a flight data recorder

with a CVR that (a) meets Technical Standard Order (TSO) C123a, (b) is

capable of recording the last 2 hours of audio, and (c) is fitted with an

independent power source that is located with the digital CVR and that

automatically engages and provides 10 minutes of operation whenever

aircraft power to the recorder ceases, either by normal shutdown or by a

loss of power to the bus. (A-99-16) 
Recommendations 40 Aircraft Accident Report

BY THE NATIONAL TRANSPORTATION SAFETY BOARD

MARK V. ROSENKER

Acting Chairman

ELLEN ENGLEMAN CONNERS

Member

DEBORAH A. P. HERSMAN

Member

KATHRYN O. HIGGINS

Member

Adopted: May 2, 2006
41 Aircraft Accident Report

5. Appendixes

Appendix A

Investigation and Public Hearing

Investigation

The National Transportation Safety Board was officially notified of this accident

on August 13, 2004, about 0300. A full go-team was assembled in Washington, D.C. The

go-team departed about 0730 and arrived on scene about 0900. The team was

accompanied by Board Member Carol Carmody.1

 

The following investigative groups were formed: Operations, Aircraft Structures,

Aircraft Systems, Aircraft Powerplants, Aircraft Maintenance Records, Meteorology, Air

Traffic Control, Aircraft Performance, Cockpit Voice Recorder, and Flight Data Recorder.

A Human Factors specialist was also assigned to review and analyze the flight crew’s

performance during the flight.

Parties to the investigation were the Federal Aviation Administration; Air Tahoma,

Inc.; and Rolls-Royce. An accredited representative from the Transportation Safety Board

of Canada (TSB) and the TSB’s technical advisor from Kelowna Flightcraft Ltd. also

assisted in the investigation.

Public Hearing

No public hearing was held for this accident.

1 Ms. Carmody is no longer with the Safety Board.
42 Aircraft Accident Report

Appendix B

Cockpit Voice Recorder Transcript

The following is the transcript of the Honeywell Sundstrand V557 model cockpit

voice recorder, serial number 2372, installed on Air Tahoma flight 185, a Convair 580,

which crashed while on approach for landing at Cincinnati/Northern Kentucky

International Airport, Covington, Kentucky, on August 13, 2004.

	
 
   
  
	 	
   

 
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