HOUSTON, TX, USA
N627WS
Gates Learjet 25B
The flight crew was positioning the airplane in preparation for a revenue flight when it crashed 2 nautical miles (nm) short of the runway during a second instrument landing system approach in instrument meteorological conditions. Except for the final 48 seconds of the 25-minute flight, the captain was the flying pilot, and the first officer was the nonflying pilot. When the airplane was about 0.5 nm inside the outer marker on the first approach, the compass warning flag on the captain's course deviation indicator appeared, indicating that the heading display was unreliable. The airplane deviated from the localizer centerline to the left but continued to descend. After about 1 minute, during which time the airplane's track continued to diverge from the localizer centerline, the flight crew executed a missed approach. The flight crew then unsuccessfully attempted to clear the compass flag by resetting circuit breakers. The captain directed the first officer to request a second approach. Contrary to company crew coordination procedures, the flight crew did not conduct an approach briefing or make altitude callouts for either approach. Although accurate heading information was available to the captain on his radio magnetic indicator, he experienced difficulty tracking the localizer course as the airplane proceeded past the outer marker on the second approach. The captain transferred control to the first officer when the airplane was 1.9 nm inside the outer marker. The airplane then began to deviate below the glideslope. The descent continued through the published decision height of 200 feet above ground level, and the airplane struck 80-foot-tall trees. Postaccident testing revealed that the first officer's instruments were displaying a false full fly-down glideslope indication because of a failed amplifier in the navigation receiver. The glideslope deficiency was discovered 2 months before the accident by another flight crew. An FAA repair station attempted to resolve the problem and misdiagnosed it as "sticking" needles in the cockpit instruments. The operator was immediately advised of the problem. The operator's minimum equipment list for the airplane required that the problem be repaired within 10 days, but the operator improperly deferred maintenance on it for 60 days and allowed the unairworthy airplane to be flown by the accident flight crew. The airplane was not equipped with, nor was it required to be equipped with, a ground proximity warning system, which would have sounded 40 seconds before impact.
HISTORY OF FLIGHT On January 13, 1998, about 0810 central standard time, a Gates Learjet 25B, N627WS, impacted terrain approximately 2 nautical miles (nm) east of the runway 26 threshold at George Bush Intercontinental Airport (IAH), Houston, Texas, during an instrument landing system (ILS) approach. (All times in this report are central standard time, based on a 24-hour clock.) The airplane was operated by American Corporate Aviation, Inc., of Houston and was registered to First Star, Inc., of Wilmington, Delaware. The positioning flight, which was operating under 14 Code of Federal Regulations (CFR) Part 91, had departed from Houston's Hobby Airport (HOU) about 0745 with a destination of IAH. The captain and first officer were the sole occupants aboard the flight. Instrument meteorological conditions prevailed for the flight, and an instrument flight rules (IFR) flight plan had been filed. Both flight crewmembers were killed, and the airplane was destroyed by impact forces and fire. Five people were waiting at IAH to board the airplane for a 14 CFR Part 135 charter flight to Fargo (FAR), North Dakota. The airplane had been operated from Raytheon Aircraft Services, a fixed-base operator (FBO) at HOU, for about 1 month before the accident flight. Raytheon's records indicated that, on January 12, 1998, the Director of Operations for American Corporate Aviation verbally requested fuel for the airplane and that the wing and tip tanks were "topped off" with 372 gallons of jet fuel. During the afternoon of January 12, the captain of the accident flight taxied the airplane from Raytheon Aircraft Services to Fletcher Aviation, another FBO at HOU, and the airplane was placed in a hangar. About 1700, the director of operations and the captain removed a stretcher from the airplane and installed two passenger seats in its place. According to the director of operations, he discussed the next day's trip to Fargo with the captain and informed him who the first officer for the flight would be. The director of operations stated that he later observed the captain giving the first officer a preflight briefing. The proposed round trip consisted of four flight segments: HOU to IAH, IAH to FAR, FAR to IAH, and IAH to HOU. According to the transcript of the telephone call, about 0528 on January 13, 1998, the captain called Montgomery County Automated Flight Service Station (CXO AFSS) and filed an instrument flight plan for a flight in N627WS from HOU to IAH and then from IAH to FAR. The proposed departure times from HOU and IAH were 0645 and 0800, respectively. When the briefer at CXO AFSS asked the captain if he could do anything else, the captain said, "yeah tell me how bad the weather is I know it is foggy as a son-of-a-gun." The captain was then given a weather briefing for the Houston and Fargo areas. The weather at IAH was reported as 1/4-mile visibility restricted by fog, vertical visibility of 100 feet, and temperature and dew point within 1 degree of each other. The forecast weather for FAR after 0900 called for unrestricted visibility and scattered clouds at 12,000 feet, becoming overcast at 10,000 feet between 1200 and 1400. The captain concluded the conversation about 0534 after saying, "well ok I'm just going to take my time and mosey on out to the airport after it gets a little better I'll get an update with you then we'll go." While this briefing was being conducted, CXO AFSS received another telephone call about 0532 requesting a weather briefing for N627WS departing HOU at 0800 for a flight to IAH and then FAR. In an interview conducted during the accident investigation, the Chief Executive Officer (CEO) of American Corporate Aviation indicated that he placed this call to CXO AFSS. The CEO was told that the weather at HOU was calm winds, 1/8-mile visibility restricted by fog, an indefinite ceiling at zero feet, and both the temperature and dew point at 19 degrees Celsius (C). The weather at IAH was reported as calm winds, 1/4-mile visibility restricted by fog, an indefinite ceiling at 100 feet, and both the temperature and dew point at 17 degrees C. The call was concluded about 0540. A line service technician employed by Fletcher Aviation stated that, when he arrived for work about 0605, the captain was already at the FBO. About 0612, the captain called CXO AFSS again, asking if the weather at IAH had gotten any better. He was told that the weather was reported as 3/4-mile visibility restricted by fog with an indefinite ceiling at 100 feet. CXO AFSS received a third call from the captain about 0646 requesting IAH weather. The captain was given a special weather report issued about 0606; the reported conditions included 1/4-mile visibility restricted by fog, light rain, indefinite ceiling at 100 feet, temperature and dew point within 1 degree, and occasional lightning in clouds from a thunderstorm to the south moving northeast. About 0706, CXO AFSS received a fourth call from the captain, asking if IAH weather had improved. The captain was told that the weather was reported as 1/4-mile visibility restricted by mist, an overcast ceiling at 100 feet, surface visibility of 4 miles, and a thunderstorm in the vicinity. According to the Fletcher Aviation line service technician, the first officer arrived at the airport between 0645 and 0700. The airplane was then moved from inside the hangar to the ramp, and the technician connected a power cart to the airplane. At that time, the technician heard fuel being transferred to the fuselage fuel tank. The technician observed the first officer fill out a "trip log" form, which the technician faxed to American Corporate Aviation's "dispatch" office after the airplane taxied out. Safety Board investigators obtained a copy of this document from the CEO of American Corporate Aviation. The form was a copy of page 9.28 of American Corporate Aviation's Operations Manual, entitled "Dispatch Record." The form indicated that the route of flight would be HOU--IAH--FAR--IAH--HOU and that the IAH--FAR--IAH portion of the flight would be operated under 14 CFR Part 135. According to cockpit voice recorder (CVR) data, the captain was the flying pilot on the flight from HOU to IAH, and the first officer was the nonflying pilot. After an uneventful takeoff from HOU, the first officer made initial contact with the IAH Terminal Radar Approach Control (TRACON) Departure North controller about 0746:21. The controller began vectoring the flight for an ILS approach to runway 26 at IAH and transmitted the following IAH automatic terminal information service (ATIS) weather conditions: [information] Echo is current. wind is three four zero at seven. visibility's one half, mist. ceiling is two hundred broken, six hundred broken, nine hundred overcast. temperature one eight. our Humble altimeter three zero, zero one. remarks, surface visibility is five. runway two six RVR [runway visual range] is more than six thousand. The Departure North controller then handed off the flight to the Arrival East controller. After a series of turns, the flight was cleared about 0751:43 for the approach to IAH and instructed to contact the IAH tower. The CVR recording does not indicate that the flight crew conducted a verbal approach briefing. About 0752:51, the IAH Air Traffic Control Tower (ATCT) Local West controller cleared the flight to land on runway 26. Radar data indicated that the airplane began a descent from 2,000 feet mean sea level (msl) about 0753:17 from about 0.5 nm inside NIXIN (the final approach fix) on the left edge of the localizer course. The airplane descended to 1,600 feet msl, where it intercepted the center of the localizer course approximately 1.5 nm inside NIXIN. About 0753:47, the CVR recorded the captain stating, "I got a compass flag." Immediately after the captain's comment, the airplane departed the localizer centerline to the left, establishing a course about 25 degrees left of the final approach course. The airplane continued on this course for approximately 50 seconds and descended to about 700 feet msl. According to CVR data, about 0754:36 the first officer said, "you wanna go missed and go back? it shows you right of course." The captain responded, "yeah yeah tell him we go missed." About 0754:41, the local controller said, "Lear uh, seven Whiskey Sierra uh, say heading." The first officer responded, "uh, we need to go missed.... we're going missed approach." A missed approach was then initiated from about 0.8 nm from the threshold of runway 27 on its extended centerline. (Runway 27 is south of and parallel to runway 26.) The flight was assigned an altitude and heading to fly and switched from local control back to approach control. About 0756:05, the first officer told the controller, "we need to go back to Intercontinental or uh back to uh, Houston Hobby." The captain said to the first officer, "no, we just need to fly around a bit." The first officer then told the controller, "captain says, uh, we're gonna fly around if you can put us out uh, we're gonna try to straighten something out." The controller asked, "do you have a problem with the aircraft?" The first officer replied, "just the compass. we're working on it." According to CVR data, the captain and first officer spent the next few minutes attempting to clear the compass flag by resetting circuit breakers. The CVR recording provides no indication that the problem was resolved. About 0759:10, the captain said, "well let's go back to Hobby, we can't, we can't do a trip like this," but then said, "well now let's think about this a second." The first officer asked the captain about the weather conditions in North Dakota. The captain replied that it was "severe clear" and then said, "uh, let's go on and try Intercontinental again." About 0759:42, the first officer requested another approach to IAH. The controller began vectoring the flight for a second ILS approach to runway 26, instructing the flight crew to "fly heading three five zero." About 0759:58, the captain said, "right turn to three five zero?" and the first officer replied "yeah." Radar data indicated the airplane began to turn right from an eastbound heading toward the south. The controller noticed that the airplane was turning southbound and instructed the flight crew to "turn northbound heading three, six, zero." The first officer acknowledged the controller's correction, and the airplane began to turn left. Afterward, the first officer made three statements to the captain about his radio magnetic indicator (RMI). The first officer said, "threeee six zero. watch your RMI" (about 0801:32); "RMI three six zero going...." (about 0801:44); and "watch the RMI" (about 0802:12). About 0801:55, the controller transmitted the following IAH ATIS weather conditions: information Foxtrot is current.... the wind three five zero at six. the uh, weather is less than a quarter mile visibility light rain and uh, mist. two hundred broken uh, measured ceiling two hundred broken six hundred overcast. altimeter three zero zero one the runway two six RVR's more than six thousand. After a series of turns, the flight was cleared about 0806:22 for the approach and instructed to contact the IAH tower. The CVR recorded no discussion or briefing on how the approach would be flown. About 0807:53, the Local North controller cleared the flight to land on runway 26. About 0808:03, the first officer said, "OK, you are cleared to land. apparently, it the glideslope (isn't) working. I can't watch it...." At this point, radar data indicated that the airplane was about 1.1 nm outside NIXIN on the glideslope and inside the left half of the localizer course. The airplane remained within the left half of the localizer course and on or slightly above the glideslope until it reached a point approximately 0.6 nm inside NIXIN. The airplane then traveled momentarily outside the left edge of the localizer course. About 0808:34, the first officer said, "...quit turning, quit turning. we're gonna go through it. follow mine right here." After the first officer's comment, the airplane's course varied slightly to the right and began to converge with the localizer course. As the airplane neared the localizer centerline (about 0808:52), the first officer said, "OK, ease your wings back. to the right, to the right, to the right...." The captain then stated, "all right. Can you fly it?" The first officer replied, "yeah, I think so." When the transfer of control from the captain to the first officer took place, the airplane was approximately 1.9 nm inside NIXIN (3.8 nm from the runway threshold), slightly below the glideslope and on the localizer centerline. About 0809:08, the captain asked, "where's your glideslope?" The first officer replied "right here," and the captain said, "look at it." About 0809:21, the first officer stated, "...we are way above glideslope." The captain responded, "right. ease it on down." At this point, the airplane was between 200 and 300 feet below the glideslope. About 0809:30, the first officer said, "all right, where's the missed approach point...?" The captain replied, "two hundred feet." (The published decision height for the approach was 296 feet msl, or 200 feet above ground level (agl).) About 0809:45, the first officer said, "OK. three hundred feet to missed. OK, I'm breaking out." The captain responded, "don't don't you look up." The last radar position for the airplane, recorded about 0809:48, was approximately 2.2 nm from the runway threshold, about 400 feet below the glideslope, at an altitude of approximately 400 feet msl. About 0809:54, the CVR recorded a slapping sound that was followed by the sound of impact. The CVR stopped recording about 0809:56. The accident occurred during daylight approximately 2 nm from the threshold of runway 26 and along the extended runway centerline. The elevation of the accident site was approximately 100 feet msl. The airplane initially struck trees about 80 feet tall. The cockpit/cabin area was found approximately 860 feet west of the initial tree strike at 29 degrees 59.563 minutes north latitude and 095 degrees 17.26 minutes west longitude. There were no witnesses to the accident. PERSONNEL INFORMATION Neither the captain nor the first officer had any Federal Aviation Administration (FAA) record of airplane accidents, incidents, or enforcement actions. Interviews with immediate family members and acquaintances disclosed no evidence of any activities that would have prevented either flight crewmember from obtaining sufficient rest in the 72 hours before the accident. The Captain The captain, age 52, held an airline transport pilot certificate with the ratings and limitations of airplane multiengine land; commercial privileges for airplane single-engine land; and type ratings for the Learjet, IA-JET, and HS-125. The captain obtained his Learjet type rating on February 6, 1987. His most recent FAA first-class medical certificate was issued on October 7, 1997, with the limitation that he wear corrective lenses for distant vision and possess corrective lenses for near vision while acting as a pilot. According to the captain's flight logbook, he had accumulated 8,777 total flying hours, of which 2,512 were in the Learjet. He had flown 19, 100, and 610 hours in the past 30 days, 90 days, and 1 year, respectively. The logbook indicated that the captain had flown one previous trip in N627WS; that trip occurred on December 23, 1997, and included about 6.9 hours of flying time. The captain's most recent Learjet recurrent simulator training was accomplished in October 1997 at the facilities of SimuFlite Training International. This training consisted of 12 hours of ground school and 9 hours of flight simulator time. Pilot training records reviewed during the accident investigation indicated that the captain had satisfactorily completed the training and testing requirements to act as pilot-in-command (PIC) of a Learjet 24 or 25 for three Houston-area 14 CFR Part 135 operators. These operators were Aviex Jet, American Corporate Aviation, and Executive Air Charter, and the required train
The flight crew's continued descent of the airplane below the glideslope and through the published decision height without visual contact with the runway environment. Also, when the captain encountered difficulty tracking the localizer course, his improper decision to continue the approach by transferring control to the first officer instead of executing a missed approach contributed to the cause. In addition, the following were factors to the accident: (1) American Corporate Aviation's failure to provide an airworthy airplane to the flight crew following maintenance, resulting in a false glideslope indication to the first officer; (2) the flight crew's failure to follow company crew coordination procedures, which called for approach briefings and altitude callouts; and (3) the lack of an FAA requirement for a ground proximity warning system on the airplane.
Source: NTSB Aviation Accident Database
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