What happened
While operating a pressurized aircraft at an altitude of 25,000 feet, the pilot began exhibiting signs of impairment. For roughly 43 minutes leading up to the accident, Air Route Traffic Control Center (ARTCC) controllers attempted to contact the pilot on six separate occasions to request altitude corrections. During communications between 2305 and 2311, the pilot's speech was noted as being unclear and slurred.
Following these transmissions, a two-minute interval occurred during which more than 30 unintended transmissions were recorded, some of which contained the sound of heavy breathing. At 2318:20, the pilot sent a final message indicating that the aircraft was in a descent and that they would rectify the situation shortly. Shortly thereafter, observers saw the aircraft enter a spin and impact the ground. There were 0 survivors of the impact.
Findings
An autopsy of the pilot identified moderate emphysema, noting the presence of air-filled bullae as large as 3 cm within the lungs. Information regarding the pilot's recent flight history indicated significant fatigue, as the owner of the aircraft noted the pilot had only slept for two hours during the two previous 4.5-hour flights. Additionally, acquaintances of the pilot reported a pattern of the pilot falling asleep easily while on the ground, though they noted this behavior became more frequent and prolonged during flight operations. The investigation highlights uncontrolled descent following a period of degraded pilot communication and physiological distress.