Flight Details
The airplane was being transported to another airport for maintenance on the autopilot system. Prior to the flight, the pilot and an avionics technician discussed a roll issue with the autopilot. The pilot was advised not to use the autopilot until the issue was resolved. The technician further advised the pilot to wait for good weather, but the pilot reportedly had a function to attend later that day.
Accident Sequence
Recorded flight track data showed that most of the flight was uneventful until the descent toward the intended destination. The airplane encountered overcast clouds during the descent. The pilot was cleared for an instrument approach. While maneuvering, the airplane descended below its assigned altitude, prompting the controller to issue a low-altitude alert. The airplane briefly climbed before entering a descending right turn that continued until the end of recorded data. Calculations indicated the airplane was descending at over 15,000 feet per minute shortly before impact. The airplane impacted the ground in a near-vertical attitude and was fragmented.
Investigation Findings
Examination of the airplane, engines, and systems revealed no preimpact anomalies that would have precluded normal flight. The pilot likely was not using the autopilot due to the known issue, and was hand-flying the airplane during the instrument approach. The pilot likely was accustomed to flying with automation rather than by hand in single-pilot instrument meteorological conditions (IMC). Based on the recorded flight path, it is likely that the pilot became spatially disoriented and lost control while intercepting the final approach course. Additionally, the pilot allowed self-imposed pressure to influence his decision to complete the flight in less-than-ideal weather without a functional autopilot.
Toxicology tests detected ethanol in liver and muscle tissue, but it is likely that some or all of it was from postmortem production. Other substances (tadalafil, salicylic acid, famotidine, atenolol, irbesartan) were detected but unlikely to have contributed.