Investigation Summary
The flight departed Orlando at 09:20 EDT. The last radio acknowledgment from the crew occurred at 09:27 EDT as the aircraft was climbing through 23,000 feet. When air traffic control attempted to contact the flight six minutes later, there was no response. The aircraft continued to climb past its assigned altitude of 39,000 feet, eventually leveling off near 51,000 feet. Several military aircraft, including F-16s and a C-130, intercepted the Learjet. The military pilots reported that the cockpit windows appeared to be frosted or opaque with condensation, and they could see no movement inside the cockpit. The aircraft flew for approximately 1,500 miles across the United States, crossing several states before the engines flamed out due to fuel exhaustion. The autopilot disconnected as the aircraft slowed toward a stall, and the plane entered a spiral descent, impacting the ground at 12:13 CDT (17:13 UTC) at nearly supersonic speed in an open field near Mina and Aberdeen, South Dakota.
Final Conclusions
The NTSB determined the probable cause was the incapacitation of the flight crew as a result of their failure to receive supplemental oxygen following a loss of cabin pressurization for undetermined reasons. While the exact cause of the depressurization could not be identified due to the extensive destruction of the aircraft, investigators noted that the crew likely succumbed to hypoxia before they could don their oxygen masks. The NTSB also highlighted that the aircraft had a history of maintenance issues related to the pressurization system, and criticized the operator for inadequate maintenance record-keeping and unauthorized maintenance deferrals. In June 2005, a Florida state court jury found that Learjet was not liable for the deaths of the passengers.
Video Analysis
The 1999 Sunjet Aviation Learjet 35A Crash — This video examines the hypoxia event and subsequent ghost flight of a Learjet 35A carrying golfer Payne Stewart. It details the cabin depressurization and the aircraft's four-hour flight on autopilot until fuel exhaustion.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Crew Experience
Captain
Had 38 hours as Learjet pilot-in-command and 22 as second-in-command.
First Officer
Had 99 hours as Learjet second-in-command; total time with operator was 251 hours.
Systems & Failure Modes
Pressurization System
The system responsible for maintaining a breathable atmosphere at high altitudes; its failure led to the crew's incapacitation.
Supplemental Oxygen System
Emergency masks and oxygen supply for the crew; though available, they were not utilized in time to prevent hypoxia.
Autopilot
Maintained the aircraft's heading and altitude for nearly four hours after the crew became unconscious.
Interesting Facts
- 01The aircraft reached a maximum altitude of approximately 51,000 feet during its unpiloted flight.
- 02The impact occurred at an extreme angle and nearly supersonic speed, leaving a crater 42 feet long, 21 feet wide, and 8 feet deep.
- 03The cockpit voice recorder only contained the final 30 minutes of the flight, which captured the sounds of engine wind-down and the stick shaker.
- 04The aircraft was not equipped with a flight data recorder (FDR).
- 05Professional golfer Payne Stewart was among the four passengers killed in the accident.
Safety Actions & Advisories
Maintenance Oversight
The NTSB recommended stricter oversight of maintenance records and pilot discrepancy reports to ensure recurring pressurization issues are properly identified.
Oxygen System Training
Source ↗The NTSB emphasized the importance of pilots immediately donning oxygen masks at the first sign of a pressurization problem, rather than attempting to diagnose the issue first, due to the rapid onset of cognitive impairment from hypoxia.
Known Controversies & Unanswered Questions
SunJet Aviation Training Records
Reference ↗In 2001, the FAA alleged that SunJet Aviation management filed false records regarding the training time for several pilots, including those on the accident flight.