NTSB CAROL · Event
Event SEA97LA159
Aircraft involved
Probable cause & findings
The pilot's failure to maintain directional control. Hypoxia and hypoglycemia were physical impairment factors.
Factual narrative
On July 6, 1997, at 1005 mountain daylight time, a Beech G35, N4552D, registered to and operated by the pilot as a 14 CFR Part 91 personal flight, ran off the side of the runway and nosed over during the landing roll at Jackson, Wyoming. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane was substantially damaged and the airline transport pilot received serious injuries. The flight had departed from Worland, Wyoming, earlier in the day. In a written statement, the pilot reported that the flight originally began on July 3, 1997, from Poughkeepsie, New York. The first leg of the flight was from Poughkeepsie, NY to Findlay, OH, for a fuel stop, then onto Sioux Falls, SD. The pilot reported that the day's flight was 9 hours and 45 minutes of flight time in instrument meteorological conditions. On July 4, 1997, the pilot took off from Sioux Falls at 0927 in visual meteorological conditions and flew to Spearfish, SD. The flight duration was two hours and 30 minutes. On July 5, 1997, the pilot stated that he took off from Spearfish fairly early in the morning and flew at 12,500 feet to Jackson, WY, until he had to turn around due to heavy rainstorms. The pilot diverted to Worland, WY, and landed after two hours and 30 minutes in the air. The pilot stated that he did not have lunch that day and his dinner that night in Worland was "tasteless and unappetizing." On July 6, 1997, the pilot reported that he was up before daylight and called Flight Service for the weather for his flight to Jackson. The pilot was advised to get an early start due to thunderstorm activity over the mountains on the route to Jackson. The pilot stated that he did not have breakfast and was "painfully hungry" before he took off from Worland. After takeoff, the pilot climbed to 12,500 feet. The pilot stated that he felt hungry and weak, and when he tried to open the valve for the oxygen, his hand was too weak to open the valve. The pilot continued the flight and stated that he was confused about turning points, altitudes, distances, and he felt "woosy." As the flight approached the Jackson area, the pilot maneuvered for landing, and had stated that he had difficulty determining pattern altitude and staying awake. The pilot stated that he put the flaps down on final approach and was continuing to have difficulty staying awake. The pilot noticed that he was low on final, and stated that with great difficulty, he pushed the throttle forward. The pilot stated that as the airplane crossed over the end of the runway, he felt that he was half asleep and not doing anything to control the airplane. The airplane landed hard and turned off to the left and exited the side of the runway. The pilot stated that the throttle was still open and he could not figure out why he was not slowing down. Finally the nose gear collapsed and the airplane nosed over. Witnesses reported that the airplane touched down very fast and then veered off the side of the runway. The witnesses who were the first to arrive at the accident site and who assisted the pilot in evacuating the airplane, reported that the pilot was disoriented and appeared "hypoxic." When the pilot was asked if he had been using oxygen, the pilot reported that he had been flying at 12,500 and that he couldn't reach the oxygen while in flight. The pilot reported that on the day of the accident, he was up before daylight to get a weather briefing for the continuation of his flight. The pilot stated that he did not have breakfast and was 'painfully hungry' before departure. The departure airport field elevation is 4,245 feet msl. After takeoff, the pilot climbed to 12,500 feet, and when he tried to open the valve for the oxygen, he reported that he could not turn it because his hand was too weak. The pilot continued the flight and reported that he was confused about turning points, altitudes, distances, and that he felt 'woosy.' The pilot reported that as he approached his destination, he had difficulty determining pattern altitude and that he was having trouble staying awake. The pilot stated that while on final approach, the airplane was low, and with great difficulty, he pushed the throttle forward. As the aircraft crossed over the end of the runway, the pilot did not feel that he was doing anything to control the airplane and that he felt that he was half asleep. The airplane landed hard and fast with the throttle still open. The airplane turned off to the left and exited the side of the runway. The nose gear collapsed and the airplane nosed over. The pilot also reported that shortly after admission to the hospital at Jackson he was told that his blood oxygen level was still down at only 60%. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12
Verbatim from NTSB's published report. Source file
NTSB_1997_SEA97LA159.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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Related research
What the literature says.
Academic papers and agency reports matching this event's aircraft type or causal vocabulary (thunderstorm). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.
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The National Aeronautics and Space Administration is conducting a research project called Storm Hazards '80 in order to study the prediction, detectability and avoidance of the hazards of severe storm…
- NASA NTRS 2019 · Preprint (Draft being sent to journal)
Nowcasting Thunderstorm Anvil Clouds Over KSC/CCAFS
Electrified thunderstorm anvil clouds extend the threat of natural and triggered lightning to space launch and landing operations far beyond the immediate vicinity of thunderstorm cells.
- NASA NTRS 2019 · Contractor Report (CR)
An Examination of Aviation Accidents Associated with Turbulence, Wind Shear and Thunderstorm
The focal point of the study reported here was the definition and examination of turbulence, wind shear and thunderstorm in relation to aviation accidents.
- NASA NTRS 2019 · Reprint (Version printed in journal)
Observations of severe turbulence near thunderstorm tops
Data derived from the flight tapes of two airliners that experienced severe turbulence near thunderstorm tops are used to produce quantitative descriptions of the turbulence and its environment.
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