Flight History
Approximately 7 minutes after takeoff, the pilot was cleared to 17,000 feet. Upon reaching that altitude, radar data showed the aircraft following a meandering flight path that increasingly deviated from the assigned course, persisting even after the controller issued multiple heading prompts. After about 6 minutes at 17,000 feet, the pilot was cleared to flight level 240 (24,000 feet). Roughly 2 minutes later, while passing through approximately 18,000 feet, the pilot made his final radio transmission, acknowledging a corrected heading. About 6 minutes after that, the aircraft reached 24,000 feet, at which point the pilot failed to provide any intelligible responses to subsequent controller inquiries. At 1456, radar indicated a descent to 21,000 feet, followed by a rapid descent and impact with terrain.
Wreckage and Systems Examination
The aircraft sustained substantial damage from the impact forces. The pilot, who was the sole occupant, sustained fatal injuries. Postaccident examination of the wreckage revealed that both bleed air switches were in the closed position, and the cabin pressurization switch on the console was in the dump position. Review of air traffic control recordings showed that none of the voice transmissions from N43KM sounded as if the pilot was speaking through an oxygen mask microphone. No other preimpact anomalies were observed that would have prevented normal operation of the airplane.
Probable Cause
The official probable cause was determined to be the pilot's failure to properly configure the pressurization controls, resulting in his impairment and subsequent incapacitation due to hypoxia.