aviation

Crash During Approach to Landing 

Business Jet Services, Ltd.

Gulfstream G-1159A (G-III), N85VT

Houston, Texas

November 22, 2004

ACCIDENT BRIEF

NTSB/AAB-06/06

PB2007-100699

Aircraft Accident Brief

Crash During Approach to Landing

Business Jet Services, Ltd.

Gulfstream G-1159A (G-III), N85VT

Houston, Texas

November 22, 2004

NTSB/AAB-06/06

PB2007-100699 National Transportation Safety Board

Notation 7828 490 LíEnfant Plaza, S.W.

Adopted November 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 Business Jet

Services, Ltd., Gulfstream G-1159A (G-III), N85VT, Houston, Texas, November 22, 2004. Aircraft

Accident Brief NTSB/AAB-06/06. Washington, DC.

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:

National Transportation Safety Board

Records Management Division, CIO-40

490 LíEnfant 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 PB2007-100699 from:

National Technical Information Service

5285 Port Royal Road

Springfield, Virginia 22161

(800) 553-6847 or (703) 605-6000

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

History Of Flight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Personnel Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

The Captain. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

The First Officer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Airplane Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Cockpit Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Ground Proximity Warning System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Meterorological Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Airport Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Minimum Safe Altitude Warning Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Flight Recorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Wreckage And Impact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Medical And Pathological Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Tests And Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Organizational and Management Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Instrument Precision Approach and Landing Guidance . . . . . . . . . . . . . . . . . . . . . . . 15

Maintenance Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Federal Aviation Administration Surveillance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Safety Recommendation A-05-08 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Additional Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Accident Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Minimum Safe Altitude Warning Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Probable Cause . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

HISTORY OF FLIGHT

On November 22, 2004, about 0615 central standard time,1 a Gulfstream G-1159A

(G-III), N85VT, operated by Business Jet Services Ltd., struck a light pole and crashed

about 3 miles southwest of William P. Hobby Airport (HOU), Houston, Texas, while on an

instrument landing system (ILS)2 approach to runway 4. The two pilots and the flight

attendant were killed, an individual in a vehicle near the airport received minor injuries,

and the airplane was destroyed by impact forces. The airplane was being operated under

the provisions of 14 Code of Federal Regulations (CFR) Part 91 on an instrument flight

rules flight plan. Instrument meteorological conditions (IMC) prevailed at the time of the

accident.

The accident flight was scheduled to depart from Dallas Love Field Airport

(DAL), Dallas, Texas, about 0500 as a positioning flight to HOU. The flight crew planned

to pick up former President George H.W. Bush and other passengers at HOU and transport

them to Guayaquil, Ecuador. The flight was scheduled to depart HOU about 0654.

The flight departed DAL about 0530. According to Business Jet Servicesí Flight

Operations and Charter Sales Manager, the departure was delayed because of poor

weather conditions at HOU and DAL. The captain was the flying pilot, and the first

officer performed the nonflying pilot duties.

At 0543:32, the flight crew received HOU automatic terminal information service

(ATIS) information ìQuebec,î which reported that the winds were calm, the visibility was

National Transportation Safety Board

Washington, D.C. 20594

Aircraft Accident Brief

Accident Number: DCA05MA011

Aircraft and Registration: Gulfstream III, N85VT

Location: Houston, Texas

Date: November 22, 2004

Adopted On: November 2, 2006

1 Unless otherwise indicated, all times in this report are central standard time based on a 24-hour

clock.

2 The ILS consists of a localizer and a glideslope, which provide lateral and vertical guidance,

respectively, during an approach. Cockpit instrumentation shows the airplaneís location relative to the

glideslope and localizer signals. Displacement is shown in terms of the airplaneís angular deviation above or

below the glideslope and left or right of the localizer. Pilots can judge the amount of displacement by needle

deflections that reference ìdotsî on the face of the instruments. 
2

NTSB/AAB-06/06

1/8 statute mile (sm) in fog, the runway visual range (RVR)3 for runway 4 was variable between

1,600 and 2,400 feet, and the clouds were broken at 100 feet and overcast at 9,000 feet.4

 At

0547:50, the cockpit voice recorder (CVR) recorded the first officer starting the approach

briefing. About 3 minutes later, the CVR recorded a discussion between the pilots about entering

the navigational approach fixes CARCO, ELREN, EISEN, and Hobby (HUB) very high

frequency omnidirectional range (VOR) in the airplaneís flight management system (FMS). The

captain asked, ìwe can probably delete HUB though, canít we?î The first officer replied, ìyeah,

we could ëcause weíre gonna have that on here for our missed [approach point].î (See figure 1 for

the runway 4 ILS published approach chart.)

At 0558:50, the first officer contacted the Houston Terminal Radar Approach Control

(TRACON) and reported, ìapproachÖGulfstream eight five Victor Tangoís with you out of one

eight zero for one one thousand [feet], [ATIS] information ëKilo.íî5 The controller cleared the

flight directly to CARCO, adding, ìwhen youíre able for the ILS runway four.î The first officer

acknowledged the transmission; however, he read back, ìILS runway one fourî instead of ì

runway four.î He then stated, ìIíll set up our ILS, in here, one oh nine nine.î 

At 0605:05, the Houston TRACON controller instructed the flight crew to descend to and

maintain 3,000 feet. Radar data indicated that, about this time, the airplane was at an altitude of

about 11,000 feet and was located about 29 miles northwest of HOU. At 0609:33, the first officer

started the before landing checklist, and, about 1 minute later, he stated, ìfive milesÖfrom

CARCO.î At 0610:43, the controller instructed the flight crew to turn left heading 070° and to

maintain an altitude of ì2,000 feet or above ëtil established [on the] localizer.î The controller then

cleared the flight for the ILS runway 4 approach. At 0611:13, the first officer stated, ìlocalizerís

alive.î (See figure 2 for the accident airplaneís ground track.) 

3 The RVR is the measurement of the visibility near the runwayís surface. The measurement represents the

horizontal distance that a pilot should be able to see down a runway from the approach end. 

4 Altitudes referenced in this report from surface weather observations and terminal aerodrome forecasts are

reported as height above ground level. All other altitudes referenced in this report are reported as height above mean

sea level.

5 As noted previously, the first officer had actually received ATIS information ìQuebec.î
3

NTSB/AAB-06/06

Figure 1. ILS runway 4 published approach chart. (Reproduced with permission of Jeppesen 

Sanderson, Inc. Not to be used for navigation.)
4

NTSB/AAB-06/06

Figure 2. Accident airplaneís ground track.

An airplane performance study conducted by the National Transportation Safety Board

indicated that, about 0611, the airplane was descending through an altitude of about 2,900 feet on

a southeasterly heading when it started turning left to converge on the ILS localizer. The airplane

continued descending during the inbound turn and leveled off at an altitude of about 2,300 feet. At

0611:41, the Houston TRACON controller instructed the flight crew to contact the HOU air

traffic control tower (ATCT). About 16 seconds later, the first officer contacted the HOU ATCT

and stated, ìwith you on the ILS.î The ATCT controller reported calm winds and then cleared the

flight to land on runway 4. The performance study indicated that, about this time, the airplane was

still at an altitude of about 2,300 feet and was located about 11 miles southwest of HOU. 
5

NTSB/AAB-06/06

At 0612:15, the captain asked the first officer to get the RVR. He then stated, ìI canít get

approach [APR] mode on my thing.î6

 The first officer replied that he could not get the APR mode

to activate either. About 0613, the airplane descended through 2,000 feet. The airplane

performance study showed that the airplane was about 1,000 feet below the glideslope about this

time and that the airplane remained 600 to 1,000 feet below the glideslope until impact.

At 0612:31, the HOU ATCT controller reported to the first officer that the RVR was

1,600 feet.7

 The first officer acknowledged the transmission. At 0612:40, the first officer stated,

ìgear down.î At 0612:57, the first officer asked, ìwhat [is]Öwrong with this?î The captain

responded, ìI donít know.î At 0613:03, the first officer further asked, ìwhat do we have set

wrong? we haveÖlong range [navigation or NAV] or somethingÖ that we shouldnít have?î Five

seconds later, the captain reported, ìgot NAVÖVOR one.î The first officer stated, ìokay, weíre

high on the glideslope now,î and the captain replied, ìjust gonna have to do it this way.î At

0613:24, the first officer stated, ìguess so. yeah youíre on [the] glideslope now.î However, the

airplane performance study showed that, about the time that the first officer made the comments

about the glideslope, the airplane was at an altitude of about 1,700 feet and was 700 feet below the

glideslope. (See figure 3 for the accident airplaneís altitude profile.)

At 0613:44, the captain asked the first officer if they were going to descend to an altitude

of 244 feet,8 and the first officer replied, ìyeah.î The airplane performance study indicated that,

about 0614, the airplane was at an altitude of about 1,000 feet. At 0614:05, the captain asked,

ìwhat happened? did you change my frequency?î The first officer responded, ìyeah we were

down thereÖthe VOR frequency was on.î He then stated, ìweíre all squared away nowÖyou got

it.î The captain responded, ìyeah, but I, I donít know if I can get back on it in time.î The first

officer replied, ìyeah you willÖyouíre squared away now.î The airplane performance study

showed that, shortly after the captainís question regarding the frequency, the airplane turned right

and subsequently intersected the ILS runway 4 localizer centerline. As shown in figure 3, about

this time, the airplane was at an altitude of about 900 feet and was 800 feet below the glideslope.

6 The airplane has an autopilot/flight director mode selector panel, and the APR mode provides flight guidance

during an ILS approach. 

7 According to the published ILS runway 4 approach chart (see figure 1), the minimum allowable RVR for an

ILS approach to runway 4 is 1,800 feet. Under 14 CFR Part 91 operations, pilots are allowed to initiate an approach

when the reported visibility is below minimums. 

8 Two hundred forty-four feet is the decision height for the ILS runway 4 approach.
6

NTSB/AAB-06/06

Figure 3. Accident airplaneís altitude profile. 

At 0614:32, the first officer stated, ìIím, Iím outside,î and, 8 seconds later, he stated,

ìokay, cominí up on two forty four.î At 0614:35, the automated radar terminal system minimum

safe altitude warning (MSAW) provided visual and aural warnings to the Houston TRACON and

HOU ATCT controllers. At 0614:42, the captain completed the before landing checklist, stating,

ìgive me full flaps.î At 0614:45.2, the CVR recorded the first officer state, ìup,î seven times in

quick succession. The CVR recorded the HOU ATCT controller simultaneously state, ìcheck

your altitude, altitude indicates four hundred feet.î The flight crew did not respond to the

controllerís transmission. No further communications were received from the flight crew. 

The airplane performance study showed that the airplane tracked the ILS runway 4

localizer and continued to descend until about 0614:47. The airplane impacted a light pole at an

altitude of about 198 feet and about 3 1/4 miles from the runway 4 threshold.
7

NTSB/AAB-06/06

PERSONNEL INFORMATION

The Captain

The captain, age 67, was hired by Business Jet Services on May 1, 1998. The captain was

the companyís chief pilot from February 15, 2000, to July 31, 2004.9

 He held a multiengine airline

transport pilot certificate with type ratings in the British Aircraft Corporation (BAC) 1-11 and the

G-III. The captain received a check airman designation from the Federal Aviation Administration

(FAA) effective December 10, 2002, and he was approved to conduct flight checks for Business

Jet Services pilots in G-III and BAC 1-11 series airplanes. The captainís most recent FAA

first-class airman medical certificate was issued on June 17, 2004, and contained the limitation

that he ìmust wear corrective lenses.î Table 1 shows the employment information reported by the

captain on the application that he filled out for Business Jet Services.

Table 1. Employment information for the captain.

Business Jet Services records indicated that the captain had accumulated about

19,000 total flight hours, 15,700 hours of which were as pilot-in-command. The captain had

accumulated 1,000 hours in Gulfstream G-II and G-III airplanes, 1 hour and 55 hours of which

were flown in the accident airplane in the 6 and 12 months preceding the accident, respectively.

The captain had flown about 400, 90, 10, 3, and 0.75 (the accident flight) hours in the last

12 months; 90, 30, and 7 days; and 24 hours, respectively. The captainís last ground training

occurred on May 18, 2004, and his last G-III proficiency check occurred on May 20, 2004. 

According to the captainís wife, the captain did not work on November 20 and 21. She

stated that the captain typically went to bed about 2230 to 2300 and awoke about 0800 on days

that he did not work. On November 21, he awoke about 0800 and went to bed about 2100. On the

morning of the accident, the captain awoke about 0220. According to a company employee, the

captain arrived at DAL about 0300, and he stated that the captain looked like he had just woken

up because he was ìslow moving.î Four company line service personnel described the captainís

actions as ìnormal.î

9 According to the captainís wife, he retired from the chief pilot position so that he could reduce his work

schedule.

Employment date Employer Job position Airplane type

June 1976 to July 1989 Jet Fleet Corporation, 

Dallas, Texas

Line captain, instructor, and 

check airman

BAC 1-11

August 1989 to March 1990 Flight International, Newport 

News, Virginia

Line captain, instructor, and 

check airman

BAC 1-11

April to October 1990 Self Freelance pilot

October 1990 to April 1998 Sky King, Inc., Sacramento, 

California

Captain, check airman, 

director of operations

BAC 1-11
8

NTSB/AAB-06/06

The First Officer

The first officer, age 62, was hired by Business Jet Services on April 19, 2004. He was the

companyís chief pilot from July 31, 2004, to the accident date. He held a single- and multiengine

airline transport pilot certificate with type ratings in Sabreliner N-265, Cessna Citation CE-500,

Hawker Siddeley HS-125, and G-III airplanes. The first officerís most recent FAA first-class

airman medical certificate was issued on September 10, 2004, and contained the limitation that he

ìmust have available glasses for near/intermediate vision.î Table 2 shows the employment

information reported by the first officer on the application that he filled out for Business Jet

Services.

Table 2. Employment information for the first officer.

Business Jet Services records indicated that the first officer had accumulated about

19,100 total flight hours, 17,700 hours of which were as pilot-in-command. The first officer had

accumulated 1,700 hours in G-II and G-III airplanes, about 18 hours of which were flown in the

accident airplane in the 8 months preceding the accident. The first officer had flown about 300,

83, 24, 8, and 0.75 (the accident flight) hours in the last 12 months; 90, 30, and 7 days; and

24 hours, respectively. The first officerís last G-III proficiency check occurred on January 25,

2004; his last line check occurred on May 20, 2004; and his last ground training occurred on

May 21, 2004. 

According to the first officerís wife, the first officer awoke about 0900 on November 20,

2004, and he went to bed about 2300. On November 21, the first officer awoke about 0900. The

first officerís wife stated that the first officer did not have regular sleeping hours and, therefore,

she was not sure exactly what time the first officer went to bed that evening; however, she thought

that it was probably about 2000. According to company personnel, on the morning of the 

Employment date Employer Job position Airplane type

July 1974 to October 1979 Eliminator Boats, Mira 

Lorna, California

Chief pilot Cessna 411 and 

Turbo Aerostar

October 1979 to December 1987 Ledo Financial Flight department 

manager and 

chief pilot

Sabreliner 60, 

Cheyenne III, and 

Cessna 414

December 1987 to November 1997 Various companies Contract pilot Hawker Jets

November 1997 to October 2001 Elite Aviation, Van Nuys, 

California

Captain G-II, G-III, and 

Hawker Jets

December 2001 to September 2002 XtraJet, Inc., Santa Monica, 

California

Captain G-II

September 2002 to April 2004 AvJet, Burbank, California; 

Sun Air Jets, Camarillo, 

California; and XtraJet

Contract pilot G-II, G-III, and 

Hawker Jets
9

NTSB/AAB-06/06

accident, the first officer arrived at DAL about 0430.10 Two line service technicians who saw him

on the morning of the accident stated that he ìseemed in good spirits.î 

AIRPLANE INFORMATION

The accident airplane was manufactured by Gulfstream Aerospace Corporation on

December 12, 1984. From October 1985 to March 1993, the airplane was operated by Jets

Ejecutivos in Mexico. The FAA issued the airplane a standard airworthiness certificate on

March 3, 1993.11 The airplane was operated by five different operators from April 1993 to

August 2000, when Business Jet Services bought the airplane. At the time of the accident, the

airplane had accumulated about 8,566 hours.

The airplane was equipped with two Rolls-Royce Spey 511-8 turbofan engines. The time

since new for the left engine was about 8,452 hours, and the time since overhaul was about

1,644 hours. The time since new for the right engine was about 8,548 hours, and the time since

overhaul was about 1,648 hours. 

Cockpit Instrumentation 

The airplane was equipped with an electronic flight instrument system (EFIS), which

consisted of two electronic displays, a symbol generator, a display controller, and a source

controller. The electronic attitude director indicator (EADI) has a fast/slow indicator that is

always visible and a glideslope indicator that is only visible when a valid ILS frequency has been

selected. If a valid frequency has not been selected, the side of the screen where the glideslope

indicator should appear remains blank. The fast/slow indicator shows airspeed guidance relative

to a target airspeed, and the glideslope indicator shows aircraft vertical deviation from the ILS

glideslope. 

The glideslope and fast/slow indicators are the same color and about the same size. Each

indicator consists of a moving pointer on a rectangular display, and each display has markers

above and below the rectangle to indicate the degree of deviation. The glideslope pointer

resembles a blunt-point arrow, and the fast/slow pointer resembles a rectangle (see figure 4). The

accident airplaneís EADI was configured with the glideslope indicator on the left side and the

fast/slow indicator on the right side.12 A review of the Safety Boardís accident database revealed

10 The first officerís wife was not sure what time he awoke on the morning of the accident, but she indicated that

he would have showered and then needed about 30 minutes to drive to the airport.

11 During a review of company records, several documents required by Federal regulations to import and operate

an airplane in the United States, including a transfer application, an export certificate of airworthiness, and a

conformity and acceptance inspection record, were not found for the accident airplane. Further, no maintenance

records were found for the time period that the accident airplane was operated in Mexico. Title 14 CFR 135.439

establishes the requirements for the retention of maintenance records.

12 FAA Advisory Circular (AC) 25-11, ìTransport Category Airplane Electronic Display Systems,î dated

July 16, 1987, provides guidance on the location of essential flight instrument displays, including the glideslope

indicator. The AC recommends standardizing the location of the glideslope indicator to the right side of the main

display; however, the accident airplane was manufactured before this guidance was issued. Five other company

airplanes flown by the accident pilots were configured with the glideslope indicator on the left side. Of these

airplanes, four had fast/slow indicators on the right side, and one had no indicator on the right side. Three of the

company airplanes flown by the accident pilots had the glideslope on the right side.
10

NTSB/AAB-06/06

no instances of accidents involving confusion of a different cockpit instrument with the glideslope

indicator.

Figure 4. A diagram of the EADI.

Note: The diagram shows the glideslope and the fast/slow indicators on the right and left side of the EADI, respectively, which is 

opposite of the accident airplaneís configuration.

The EFIS source controller is used to select attitude, heading, navigation, and bearing

sources for display on the EADI. The NAV button on the source controller is used to control the

source of the very high frequency (VHF) NAV information. When a frequency is entered in the

VHF NAV receivers, it is stored in the standby position. The standby frequency can be activated

instantly by flipping a toggle switch located next to the frequency display. The display data

include the selected course and the course, localizer, and glideslope deviations.

The airplane was equipped with an autopilot/flight director mode selector panel. The APR

mode is used during an ILS approach. An ILS frequency must be selected as the NAV source and

valid ILS signals must be received for the APR mode to activate. When these conditions are met

and the APR button is pressed, both the NAV and APR modes are armed to capture the localizer

and glideslope, respectively. When the APR mode is activated, the flight directorís lateral and

vertical modes, including the glideslope and localizer captured and armed modes, are annunciated

on the top of the EADI display. According to CVR information, neither the first officer nor the

captain was initially able to activate the APR mode on their flight directors.
11

NTSB/AAB-06/06

The airplane was equipped with an FMS that had a multifunction display (MFD), which

was located on the center instrument panel and displayed navigational approach waypoints13 that

are entered into the FMS by the flight crew. As the airplane proceeds toward the airport, the

displayed waypoint numbers change position on the MFD relative to a fixed airplane symbol at

the bottom of the screen. An FMS does not provide the minimum altitudes for each navigational

approach waypoint and supplements the airplaneís other navigational guidance instruments.

Ground Proximity Warning System

The airplane was equipped with a Honeywell Mark VI ground proximity warning system

(GPWS), which provides aural alerts when thresholds are exceeded in several operational

modes.14 Specifically, an aural ìtoo low terrainî alert will be generated when the airplane reaches

a specific allowable altitude for a given airspeed and the landing gear is down. Also, when a valid

glideslope frequency has been selected on the captainís NAV receiver and the landing gear is

down, an aural ìglideslopeî alert will be generated and repeated every 3 seconds if the airplane

deviates below the glideslope by more than 1.3 dots and if the altitude is below 1,000 feet. The

ìglideslopeî alert gets louder as the airplane descends below 300 feet. If a valid ILS frequency

has not been selected on the NAV receiver, the ìglideslopeî alert is inhibited.

In addition, when the airplane descends below 500 and 200 feet and deviates below the

glideslope by more than 1.3 dots and a valid ILS frequency has been selected, ì500î and

ì200î foot aural alerts will be generated. The GPWS also generates a ìminimumsî alert when the

airplane descends to the decision height (DH) selected by the flight crew. The CVR did not record

any GPWS alerts during the accident flight. 

An avionics functional check of the GPWS, which consists of a self-test and audio level

check, is conducted by maintenance personnel every 12 months. The last maintenance functional

check of the accident GPWS occurred on April 2, 2004, and no discrepancies were noted.

According to the director of training at Business Jet Services, company pilots also perform

preflight avionics functional checks. The director, who had flown a series of flights in the accident

airplane during the 4 days before the accident, indicated that the airplaneís GPWS tested normally

during the preflight checks. He also stated that, within the last year, he had received a valid

in-flight ìglideslopeî alert while flying low on the glideslope during a visual approach. Other

company pilots who had recently flown the accident airplane reported no problems with the

GPWS during the preflight checks. According to Honeywell, the only common failure that could

prevent activation of the GPWS glideslope and altitude callouts is a radio altimeter failure. No

evidence was found indicating that there were any problems with the radio altimeter. 

METEOROLOGICAL INFORMATION 

National Weather Service (NWS) surface analysis station models showed, about 0600, a

low pressure area centered over northern Mexico and two frontal boundaries extended through

13 The MFD displays a number for each approach waypoint, which indicates the waypointís chronological order

in the waypoint list.

14 Federal regulations required that all turbine engine-powered airplanes with six or more passenger seats be

equipped with an enhanced ground proximity warning system (EGPWS) by March 29, 2005. The EGPWS provides

pilots with a pictorial view of terrain in addition to the aural alerts provided by the GPWS.
12

NTSB/AAB-06/06

central and southern Texas. Station models in southeastern Texas showed that surface winds were

generally less than 5 knots and that mist and light rain existed in the area.

A Terminal Aerodrome Forecast prepared by the NWS for HOU, which was valid at the

time of the accident, stated, in part, the following: Wind at 100° at 5 knots, visibility 1/4 sm in

fog, vertical visibility15 100 feet. The NWS issued a dense fog advisory at 0159 local time on

November 22, which was valid at the time of the accident and warned of a large area of fog over

the surrounding area and of visibility of less than 1/4 sm.

About 0245 local time, the NWS issued Airmanís Meteorological Information (AIRMET)

ìSierra,î which covered the area surrounding the airplaneís flightpath and was valid at the time of

the accident. AIRMET ìSierraî warned of occasional ceilings below 1,000 feet and/or visibility

below 3 sm in precipitation, mist, and/or fog. About 0455 local time, the NWS issued a

convective significant meteorological information (SIGMET),16 which covered the area near the

accident site and was valid at the time of the accident. The SIGMET warned of embedded

thunderstorms moving from 250° at 20 knots, with cloud tops above 45,000 feet.

Weather observations at HOU are made by an automated surface observing system

(ASOS), which is located about 4 miles northeast of the accident site at an elevation of about

45 feet. ASOS transmits official meteorological aerodrome reports (METAR) 53 minutes past

each hour and special weather observations (SPECI) as conditions warrant, including wind shift,

visibility change, and cloud cover or height ceiling change. The 0553 METAR reported that winds

were 110° at 3 knots; the tower visibility was 1/8 sm in fog; the sky condition was clouds

scattered at 100 feet, broken at 600 feet, and overcast at 5,500 feet; and the surface visibility was

1/2 sm. The HOU ASOS issued SPECIs at 0605 and 0627 because the cloud ceiling had changed

from scattered to broken at 100 feet and from broken to overcast at 600 feet, respectively. The

HOU ASOS provides unofficial weather observations that are recorded every 5 minutes. At 0615,

the HOU ASOS reported that winds were 90° at 3 knots, the tower visibility was 1/8 sm in fog,

the sky condition was clouds broken at 100 feet and overcast at 600 feet, and the surface visibility

was 1/2 sm. 

AIRPORT INFORMATION

HOU is located about 8 miles southeast of Houston at an elevation of 46 feet. Runway 4 is

equipped with a medium intensity approach lighting system with runway alignment indicator

lights, high intensity runway edge lights, touchdown lights, and centerline lights. The approach

end of runway 4 at HOU is equipped with a suite of sensors that measure the RVR. 

Minimum Safe Altitude Warning Information

Houston TRACON provides approach control services to the HOU ATCT. Houston

TRACON is equipped with an automated radar terminal system IIIA radar data processing unit

15 Vertical visibility is defined as the vertical distance a person can see from the surface of the earth to the

obscuring phenomenon. 

16 Convective SIGMETs are issued when severe thunderstorms and embedded thunderstorms occur for more

than 30 minutes of the valid period, regardless of the size of the area; when a line of thunderstorms exists; or when an

area of active thunderstorms affecting at least 3,000 square miles exists.
13

NTSB/AAB-06/06

with an MSAW capability that monitors an aircraftís separation from terrain and obstacles. The

MSAW warnings are provided at the TRACON and at the HOU ATCT. The MSAW operates in

two modes: general terrain monitor (GTM) mode, which monitors aircraft clearance above the

highest terrain and obstacles in a general area, and the approach monitor (AM) mode, which

monitors aircraft clearance above terrain and obstacles within a specific area on a certain runway

approach (known as the Type II Airport Area). Each of these modes alerts controllers when an

aircraft is currently below or predicted to go below an established minimum safe altitude. If the

minimum safe altitude thresholds are exceeded, the MSAW will provide air traffic controllers

with both a visual alarm (a blinking ìLAî [low altitude] on the controllerís screen) and an aural

alert. 

A predicted monitor alert will activate if two out of three consecutive radar scans show

that the aircraft will descend 100 feet below the minimum altitude within the next 15 seconds. A

current monitor alert will activate if a single radar scan shows that the aircraft is below the

minimum altitude. The MSAW recorded a single GTM predicted exceedance of the established

minimum safe altitude of 400 feet at 0613:30, but neither of the two subsequent scans predicted

that the airplane would descend below the minimum altitude; therefore, no alert was generated at

this time. The MSAW recorded no AM predicted exceedances; therefore, no AM predicted alerts

were generated. The MSAW generated an AM current alert at 0614:35. The HOU ATCT

controller began issuing a warning to the flight crew about 7.5 seconds after the alert activated,

which was about 3 to 4 seconds before impact with the light pole. 

The Safety Board evaluated the airplaneís flight profile and the MSAW algorithms for the

HOU airport area to determine whether the MSAW provided the HOU ATCT controller the alerts

expected given the design specifications of the system. The study indicated that the system

performed as designed. The study also indicated that the descent profile of the accident flight was

along the edge of the GTM predicted alert threshold, such that only one GTM predicted alert was

recorded by the system. 

During discussions with FAA staff about MSAW-related safety issues, FAA personnel

noted that, in an effort to limit ìnuisance alarms,î MSAW parameters are presently set to not

trigger an alarm for aircraft that routinely fly visual approaches lower than any precision

instrument approach. Because the present MSAW design does not provide any way to alter

system performance to treat aircraft flying visual approaches differently from aircraft flying

instrument approaches, aircraft that deviate from instrument approach limits during IMC may not

generate an MSAW alert until they are well below the expected instrument approach altitude.

On July 11, 2006, the Safety Board issued safety recommendations to the FAA that

addressed MSAW alert effectiveness.17 In its recommendation letter, the Board noted that

modifying MSAW software to apply different alerting parameters to aircraft flying visual and

instrument approaches will likely decrease the number of false alarms when aircraft are in visual

approach conditions and increase warning times when aircraft are instrument dependent, which

will increase the credibility and overall effectiveness of MSAW warnings and likely improve

controllersí ability to detect hazards and potentially prevent accidents.

17 For more information, see the Safety Boardís Web site at

<http://www.ntsb.gov/Recs/letters/2006/A06_44_47.pdf.>
14

NTSB/AAB-06/06

FLIGHT RECORDERS

The accident airplane was equipped with a Fairchild model A-100 CVR. The exterior of

the CVR showed no evidence of structural damage. The CVR was sent to the Safety Boardís

laboratory in Washington, D.C., for readout and evaluation. The interior of the CVR and the tape

sustained no apparent heat or impact damage. The recording started at 0543:32 and continued

uninterrupted until 0614:47. The recording consisted of two channels of ìgood qualityî audio

information, the cockpit area microphone and the combined captain and first officer audio panel

information, and two channels of low level audio that was unusable. 

The accident airplane was equipped with an L-3 Communications Fairchild model F1000

flight data recorder (FDR). The FDR used solid-state flash memory as the recording medium and

was configured to record a minimum of 25 hours of flight data. The recorder was found to be in

good condition. The FDR was sent to the Safety Boardís laboratory for readout and evaluation.

About 122 hours of data were recorded on the FDR, including data from the accident flight. 

WRECKAGE AND IMPACT INFORMATION

The airplane impacted the top of a light pole about 198 feet above the ground. Pieces of

the right wing inboard leading edge were found embedded in the joint that attaches the light

fixture to the pole. Numerous pieces of the right wing inboard leading edge, upper and lower right

wing skin, and the right main landing gear door were found between the light pole and the initial

ground impact mark, which was about 790 feet northeast of the light pole. 

The initial portion of the ground impact mark extended about 110 feet along a magnetic

heading of 035°. Numerous pieces of the left wing outboard leading edge were found embedded

in the ground along the gouge mark. The left wing tip was found near the gouge mark about

50 feet from the initial ground impact mark. The airplaneís main wreckage, which contained the

majority of the airplaneís forward fuselage and cockpit, was found beyond the ground impact

mark. All of the airplane structure, including the fuselage, wings, and empennage, were found

along the wreckage path.

Both engines were found separated from the airplane. The engines showed no indications

of uncontainment, case rupture, or in-flight fire. The left engine low pressure compressor blades

were found in place and bent opposite the direction of rotation. The right engine low pressure

compressor blades were found in place and straight, with no circumferential rub marks.

Postaccident disassembly of the engines revealed no preexisting defects or malfunctions, and

testing of both enginesí fuel controls showed that they were functioning normally.

MEDICAL AND PATHOLOGICAL INFORMATION

Tissue and fluid specimens from both pilots tested negative for a wide range of drugs,

including major drugs of abuse. The captainís specimen tested positive for ethanol, but the

analysis indicated that the detected ethanol most likely resulted from postmortem formation. 
15

NTSB/AAB-06/06

TESTS AND RESEARCH

Flight simulations were conducted to determine whether any GPWS alerts would have

been expected during the flight with parameters, such as altitude, airspeed, and glideslope

deviation, set to approximate the conditions of the accident flight profile. The simulations showed

that the airplane penetrated the descent-below-glideslope alert envelope at an altitude of about

925 feet, by which time, the ILS frequency had been selected by the first officer and the landing

gear commanded down. The airplane penetrated the insufficient terrain clearance alert envelope at

an altitude of about 255 feet. Therefore, the ìglideslopeî and ìtoo low terrainî alerts, respectively,

should have activated. The simulations also showed that the ì500î and ì200î feet aural alerts

should have activated.

Postaccident tests using an engineering bench test unit were also conducted to verify

whether GPWS alerts would be generated with parameters set to approximate the accident flight

profile. The tests showed that, at an altitude about 915 feet, the ìglideslopeî alert sounded and

repeated. During the tests, the altitude was continually reduced, and the following was noted:

about 500 feet, the ì500î foot alert sounded; about 300 feet, the ìglideslopeî alert got louder;

about 272 feet, the ìtoo low terrainî alert sounded and repeated; about 244 feet, the ìminimumsî

alert sounded; and, about 200 feet, the ì200î foot alert sounded. 

ORGANIZATIONAL AND MANAGEMENT INFORMATION

Business Jet Services is an aviation management company that specializes in management

services for corporate aircraft owners and provides Part 135 on-demand charter services

worldwide. At the time of the accident, the company had about 100 employees, including 35

Part 135 pilots, and a fleet of 13 airplanes, 7 of which were Gulfstreams. 

Instrument Precision Approach and Landing Guidance

According to Business Jet Servicesí Gulfstream III Standard Operating Procedures

(SOPs), after the flight crew reviews the descent procedures, the flying pilot is required to brief

the approach, including the airplane configuration (such as the flap setting) and the final approach

fix (FAF) altitude. The SOPs state that as many checklist items as possible should be

accomplished and that the approach checklist must be completed before the initial approach fix.

The CVR recorded the first officer accomplishing the approach briefing; however, the CVR did

not record him mentioning the airplaneís configuration or the FAF altitude, which was 1,500 feet.

The SOPs also indicate that, at initial convergence of the localizer, the flying pilot is

required to call out, ìlocalizer alive,î and, at initial downward needle movement of the glideslope

indicator, to call out, ìglideslope alive.î Further, the flying pilot is required to call out, ìone dot to

go,î when the airplane is one dot below the glideslope; ìlocalizer captured,î when the

annunciator indicates that the localizer has been captured; and, ìglideslope captured,î when the

annunciator indicates that the glideslope has been captured. CVR evidence indicates that the first

officer called out, ìlocalizer alive,î but that he did not call out, ìglideslope alive,î or, ìone dot to

go.î The CVR transcript indicates that the first officer made the first glideslope-related callout at

0613:14, when he stated, ìweíre high on the glideslope.î 
16

NTSB/AAB-06/06

The SOPs also state that, no later than the FAF crosscheck, the nonflying pilot should tune

the VHF NAV receivers to a specific frequency and then identify and monitor the frequency.18

The nonflying pilot is also required to call out when the airplane is 1,000, 500, 200, and 100 feet

above the DH and when the localizer and glideslope deviate one dot or more. The CVR transcript

indicated that, although the first officer tuned the VHF frequency in the standby position earlier in

the flight, he did not switch the VHF NAV receivers from the HUB VOR frequency to the ILS

frequency until the airplane was at an altitude of about 1,000 feet nor did he identify or monitor

the frequency. Further, the CVR did not record either pilot making any altitude or deviation

callouts. 

Business Jet Servicesí stabilized approach criteria require that, within 500 feet of the

touchdown elevation, the airplane must be within the approach window, which requires, in part,

that the glideslope and the localizer must not deviate more than one dot and that the descent rate

must be less than 1,000 feet per minute (fpm). If the airplane is not within these criteria, the

nonflying pilot should call out, ìmissed approach,î and a go-around should be executed.

According to the Safety Boardís airplane performance study, about the time that the airplane was

at an altitude of about 500 feet, the glideslope display would have shown a deviation of more than

one dot and the descent rate would have exceeded 1,000 fpm. The CVR did not record either pilot

call for a missed approach or initiate a go-around.

Maintenance Records

During a review of Business Jet Services maintenance inspection records, Safety Board

investigators noted several discrepancies, including missing inspector signoffs, missing stamps

and dates of maintenance actions, and other missing information. Many of the Form 337s, which

are used to document major repairs and alterations, noted that they were approved by the

Oklahoma City Flight Standards District Office (FSDO); however, no approving documentation

was attached to the forms. In addition, although several records were found indicating compliance

with airworthiness directives (AD), in many of these cases, no records were found pertaining to

work accomplished for compliance with the ADs. 

Federal Aviation Administration Surveillance

Business Jet Services was initially certificated on July 24, 1998, by the Dallas FSDO. On

March 15, 2000, the companyís operating certificate was transferred to the Oklahoma City FSDO.

The Business Jet Services principal maintenance inspector (PMI), who was based in Oklahoma

City, had been in that position since 2000. The PMI was also responsible for the surveillance of

three other Part 135 operators, four repair stations, one flight school, and one airplane and

powerplants school.

A review of the FAAís Program Tracking and Recording Subsystem records indicated that,

from January to November 2004, the PMI visited Business Jet Services 15 times and

accomplished all of the required surveillance items, which included a maintenance records review

18 To identify a frequency, the nonflying pilot listens for a specific, audible Morse-code pattern, which is

received by the VHF NAV receivers.
17

NTSB/AAB-06/06

on May 6, 2004. No maintenance procedures or record-keeping discrepancies were noted by the

PMI in the FAAís records. 

Safety Recommendation A-05-08

As a result of the June 13, 2003, Air Sunshine, Inc., flight 527 accident, the Safety Board

issued Safety Recommendation A-05-08, which asked the FAA to do the following:

Review the procedures used during its oversight of Air Sunshine, including those for the

Surveillance and Evaluation Program [SEP] and Regional Aviation Safety Inspection

Program, to determine why the inspections failed to ensure that operational and

maintenance issues that existed at the company were corrected. On the basis of the

findings of this review, modify Part 135 inspection procedures to ensure that such issues,

including maintenance record-keeping and practices, are identified and corrected before

accidents occur.19

In response to the safety recommendation, the FAA indicated that it will review and revise

FAA Order 8300.10, ìAirworthiness Inspectorís Handbook,î to enhance inspectorsí awareness of

inadequate record-keeping systems and the timely correction of record-keeping discrepancies.

The FAA noted that because the SEP was designed and used for Part 12l operators, it was not

applicable to Air Sunshine. The FAA stated that FAA Order 1800.56, ìNational Flight Standards

Work Program Guidelines,î provided guidelines for the establishment of a surveillance work

program. Pending the FAAís revisions to Order 8300.10, Safety Recommendation A-05-08 was

classified ìOpenóAcceptable Response,î on January 18, 2006.

ADDITIONAL INFORMATION

FAA Order 7110.65, ìAir Traffic Control,î states that approach controllers are required to

issue the current touchdown RVR for the runways in use when the prevailing visibility is 1 mile or

less or when the RVR indicates a reportable value (an RVR that is fewer than 6,000 feet). FAA

Order 7110.65 also states that approach ìcontrollers shall ensure that pilots receive the most

current pertinent weather information. Ask the pilot to confirm receipt of the current ATIS

information if the pilot does not initially state the appropriate ATIS code.î The CVR did not

record the Houston TRACON controller question the first officer when he stated that he had ATIS

information ìKiloî instead of information ìQuebecî; notify the flight crew of the current ATIS,

which at that time was information ìRomeoî; or provide the flight crew with the current RVR.

19 For more information, see the Boardís Web site at <http://www.ntsb.gov/Recs/letters/2005/A05_08_10.pdf.>
18

NTSB/AAB-06/06

ANALYSIS

General

The flight crew was performing an instrument precision approach; therefore, the presence

of low cloud ceilings and reduced visibility should not have affected the pilotsí ability to fly the

approach.

The Houston TRACON controller did not correct the first officer when he stated that he

had ATIS information ìKiloî instead of ìQuebecî; confirm that the flight crew had the most

current weather, ATIS information ìRomeo,î and RVR; or question the first officer when he read

back the incorrect runway assignment,20 as required by FAA Order 7110.65. However, because

the RVR and weather conditions had not changed considerably since the time the first officer

received the information and the CVR recorded the flight crew correctly reference the runway

later in the approach, the controllerís errors did not contribute to the accident. 

Postaccident benchtests set to parameters approximating the accident flight profile

showed that the ìglideslope,î ì500î foot, ìtoo low terrain,î ìminimums,î ì300î foot, and ì200î

foot GPWS alerts should have activated on the accident flight. However, the CVR did not record

the accident GPWS generate any alerts during the flight. The only common failure that could

prevent activation of the GPWS glideslope and altitude callouts is a radio altimeter failure.

However, a review of Business Jet Servicesí maintenance records and the CVR transcript found

no evidence indicating any problems with the radio altimeter. The GPWS unit and the radio

altimeter were destroyed during impact; therefore, the Safety Board was unable to determine why

the GPWS did not operate as expected. Federal regulations would have required that the accident

airplane be equipped with an EGPWS by March 29, 2005. The EGPWS provides pilots with a

pictorial view of terrain in addition to aural alerts.

A review of the FAAís Program Tracking and Reporting System records indicated that the

PMI reviewed company maintenance records, which is a required inspection item, on May 6,

2004, and no discrepancies were noted. However, a Safety Board review of the companyís

maintenance records revealed that some of the maintenance paperwork was inconsistent,

incomplete, and/or not documented properly. The Board is concerned that, although the FAA

PMIís oversight of Business Jet Services was in accordance with standard guidelines, the PMI did

not detect the maintenance records deficiencies found during the investigation. As noted

previously, the Safety Board addressed this issue by issuing Safety Recommendation A-05-08,

which is currently classified ìOpenóAcceptable Response,î pending the FAAís revisions to

Order 8300.10.

Accident Sequence

The examination of CVR and FDR data indicated that the en route portion of the accident

flight from DAL to HOU was routine. The first officer started the approach briefing about

0547:50. However, Business Jet Servicesí SOPs state that the flying pilotóin this case, the

20 At 0559:06, the CVR recorded the first officer read back ìrunway one fourî instead of ìrunway four.î
19

NTSB/AAB-06/06

captainóshould brief the approach. Further, during the briefing, the first officer did not mention

all of the approach checklist items, including the FAF altitude. 

About 3 minutes after starting the approach briefing, the CVR recorded the captain asking

the first officer to set the navigational approach waypoints in the FMS. The pilots then discussed

deleting the HUB VOR waypoint from the list, which the first officer most likely did at that time.

The MFD only displays a chronological number for each approach waypoint; therefore, it is

possible that the flight crew forgot that the first officer removed the HUB waypoint from the

FMS, causing them to mistakenly believe that the last waypoint displayed on the MFD (EISEN)

was the airport. Regardless, an FMS serves as a secondary navigational aid on an ILS approach.

The pilots should have been relying on the primary navigational aids during the approach.

About 0612, the CVR recorded both pilots stating that they were unable to get the APR

mode on their flight directors to activate. About 1 minute later, the first officer told the captain

that they were ìhigh onî the glideslope and then that they were ìonî the glideslope. According to

the airplane performance study, the airplane was actually about 700 feet below the glideslope

when the first officer made these statements, and the airplane remained well below the glideslope

throughout the rest of the approach. Although the first officer entered the ILS frequency in the

standby position in both VHF NAV receivers earlier in the approach (about 0559, after the

approach clearance), at this point in the approach, neither pilot had selected the ILS frequency.

Further, the glideslope indicator would not have been visible on the EADI. Therefore, the first

officer could not have been looking at the glideslope indicator when he made the statements about

the glideslope. 

The first officerís failure to activate and identify the ILS frequency earlier in the approach

prevented the flight crew from recognizing that the airplane was off course and below the

glideslope. The fast/slow indicator on the EADI resembles the glideslope indicator and is visible

on the EADI at all times, whereas the glideslope indicator only appears on the screen once an ILS

frequency has been activated. Postaccident flight simulations revealed that the fast/slow indicator

would have been centered within one dot during the approach sequence and that the indications

would have been consistent with the first officerís comments about the glideslope if he had

mistaken the fast/slow indicator for the glideslope indicator.

The first officer did not switch the VOR frequency to the ILS frequency until about

1 minute before impact. When the first officer realized that he had not switched to the ILS

frequency, he should have called for a missed approach because the airplane was not properly

configured for the approach and was not receiving proper vertical guidance during the most

critical phase of the flight. Once the first officer selected the ILS frequency, the glideslope

indicator would have appeared on the screen and both pilotsí displays would have shown a

full-scale deviation below the glideslope and a full-scale or near full-scale deviation of the

localizer; however, the CVR did not record either pilot mention the glideslope deviation. The

fast/slow indicator would have remained visible on the EADI even after the ILS frequency was

selected, which may explain why the pilots did not immediately notice the glideslope indicator

deviation after the first officer selected the ILS frequency. Therefore, the pilots most likely

mistook the fast/slow indicator for the glideslope indicator throughout the approach sequence. 
20

NTSB/AAB-06/06

The Safety Board is concerned that the first officer switched the frequency of a primary

navigational aid and failed to inform the captain. If the pilot-not-flying takes such actions without

first checking with or simultaneously informing the flying pilot, confusion can occur, as

evidenced by the captainís remark, ìWhat happened? Did you change my frequency?î In this

case, because the airplane was at such a low altitude (about 1,000 feet) in IMC, such a major

change should have prompted the captain to immediately initiate a missed approach. 

Shortly after activating the ILS frequency, the first officer stated, ìweíre all squared away

now.î The captain replied, ìI donít know if I can get back on it [the ILS localizer] in time.î The

first officer stated, ìyeah you will. youíre squared away now.î These comments indicate that the

pilots were focused on correcting the localizer deviation. The first officer dismissed the captainís

concerns, and the captain did not proceed to assert his authority. As noted, earlier in the approach,

the flight crew had attempted unsuccessfully to activate the flight director APR mode, and no

evidence indicates that either pilot tried to reactivate the APR mode on their flight directors once

the ILS frequency was selected. Therefore, the flight crew continued to perform the approach

without the advantage of flight director guidance. The CVR did not record the pilots making any

of the required altitude callouts, except at 0614:40, when the first officer announced that they had

reached the DH of 244 feet. The airplane hit the light pole immediately thereafter. 

FDR data show that the airplane exceeded a descent rate of 1,000 fpm within 500 feet of

the touchdown elevation, which was outside of the stabilized approach window. In addition,

although the localizer deviation was less than one dot by the time the airplane reached 500 feet,

the localizer would have shown a full-scale or near full-scale deviation of the localizer when the

first officer initially activated the ILS frequency. Both of these factors should also have prompted

the flight crew to initiate a missed approach. 

Throughout the approach, the flight crew failed to follow approved company approach

procedures. The first officerís failure to activate and identify the ILS frequency at the appropriate

point in the approach prevented the pilots from receiving glideslope and localizer information on

their EADIs until late in the approach. Further, the pilotsí failure to engage the APR mode on their

flight directors after the ILS frequency was selected prevented them from receiving flight director

guidance. In addition, neither pilot was adequately scanning the cockpit instruments. Compliance

with standard company procedures, activating and identifying the ILS frequency and

subsequently the APR mode, and adequate monitoring of the flight instruments would likely have

prevented the accident.

Fatigue might have also played a role in the flight crewís degraded situational awareness.

According to the captainís wife, on the night before the accident, the captain received about

4 hours less sleep than normal. A company employee stated that, when the captain arrived for

work on the morning of the accident, he looked as though he had just woken up. The first officerís

wife stated that the first officer did not have regular sleeping hours and that she was not sure how

much sleep he got the night before the accident. Although the early reporting time for the accident

flight might have resulted in flight crew fatigue, the actual amount and quality of sleep received

by the captain and the first officer could not be determined. Regardless, their improper conduct of

the approach reflected fundamental operational shortcomings that were independent of fatigue.
21

NTSB/AAB-06/06

Minimum Safe Altitude Warning Operation

The Safety Board evaluated the airplaneís flight profile and the MSAW algorithms for the

HOU airport area and determined that the MSAW performed as designed given the alert

thresholds established for the HOU airport area. The study determined that the accident descent

profile was along the edge of the MSAW GTM predicted alert threshold. In this case, although the

MSAW recorded a single predicted exceedance of the threshold at 0614:30, the two subsequent

scans did not predict exceedances; therefore, no GTM predicted alert was generated.

The MSAW generated an AM current alert at 0614:35. The HOU ATCT controller began

issuing a low-altitude warning to the flight crew about 7.5 seconds later. Analysis of the MSAWís

performance found that the system provided only about 11.5 seconds of warning time before the

airplane struck the light pole, which was not sufficient time for the controller to recognize the

alert and warn the flight crew in time to prevent the accident. Configuring a single set of MSAW

parameters is a balancing act between minimizing ìnuisance alarmsî and providing sufficient

warning time. Implementing software and adaptation modifications to minimize or eliminate

unwarranted MSAW alerts without degrading the usefulness and safety benefit of MSAW will

increase the credibility and overall effectiveness of MSAW warnings. Such modifications will

likely improve controllersí ability to detect hazards and potentially prevent controlled flight into

terrain accidents. As noted previously, in July 2006, the Safety Board issued safety

recommendations to the FAA that addressed MSAW alert effectiveness.

PROBABLE CAUSE

The National Transportation Safety Board determines that the probable cause of this

accident was the flight crewís failure to adequately monitor and cross-check the flight instruments

during the approach. Contributing to the accident was the flight crewís failure to select the

instrument landing system frequency in a timely manner and to adhere to approved company

approach procedures, including the stabilized approach criteria.