Flight and Incident Overview
A commercial pilot departed on a planned 1-hour cargo cross-country flight in an autopilot-equipped airplane. About 3 minutes after departure, the controller instructed the pilot to fly direct to the destination airport at 2,000 ft msl. The pilot acknowledged, and no further radio transmissions were received from the airplane.
The airplane continued past the destination in straight-and-level flight at 2,100 ft msl, consistent with autopilot operation, until it was about 100 miles beyond the destination. A witness observed the airplane fly overhead at low altitude, heard three "pops," then saw it bank left and descend. The airplane continued in a descending left turn until it disappeared below the horizon.
Impact and Wreckage
The airplane struck trees in about a 45° left bank with a level pitch attitude and came to rest in heavily wooded terrain. The airplane sustained extensive thermal damage from a postcrash fire. Examination of remaining airframe, flight controls, engines, and accessories revealed no preimpact failure or malfunction. The fuel selector valves were positioned on the outboard tanks, consistent with normal cruise procedures in the pilot's operating handbook.
Fuel Analysis
According to the airplane's flight records and fuel consumption data from the engine manual, the outboard tanks contained sufficient fuel for about 1 hour 10 minutes of flight at departure. The accident occurred after approximately 1 hour 15 minutes of flight. Therefore, it is likely that the outboard tanks were exhausted, and without pilot action to switch tanks, the engines lost power due to fuel starvation, resulting in descent and impact.
Pilot Incapacitation
The overflight of the destination and subsequent fuel starvation indicate pilot incapacitation. The pilot's autopsy identified no significant natural disease, but the examination was limited by the severity of body damage. Various conditions, such as cardiac arrhythmias, seizures, or other causes of loss of consciousness, could incapacitate a pilot without leaving autopsy evidence. Toxicology results showed that the pilot had used marijuana/THC before the accident. THC can impair judgment but does not cause incapacitation, and the circumstances are not consistent with impairment from THC; thus, THC use likely did not contribute.
The reason for the pilot's incapacitation could not be determined.