Accident Overview
An investigation into an aircraft accident revealed that the pilot experienced spatial disorientation, leading to a loss of control. No record could be found indicating the pilot received a weather briefing prior to departure, despite unfavorable weather in the vicinity. During the flight, the pilot had difficulties understanding and complying with instructions from various air traffic control services.
Flight Sequence
After takeoff, the pilot requested and received an IFR clearance. Radar returns from the last five minutes of flight showed the aircraft changing heading from 45° to as much as 180° about ten times, and also descending or ascending several times between 4,500 feet and 11,500 feet mean sea level. These altitude and heading changes were not directed by controllers. Approximately three minutes before the accident, departure control asked the pilot if he had a problem. The pilot responded affirmatively, stating, 'we're trying to get straight.' One minute later, the pilot said, 'we're all right.' Shortly thereafter, radar data indicated a loss of control, followed by loss of radar and communications, and an on-ground explosion was observed.
Medical and Weather Factors
An FAA flight surgeon reviewed the pilot's medical records and found that within one year of the accident, the pilot had three physical conditions and was taking three separate prescriptions that would have prevented him from being medically qualified to pilot an aircraft. All seven occupants were killed.
Probable Cause
The official finding attributed the accident to the pilot's failure to maintain aircraft control due to spatial disorientation. Contributing factors included the pilot's failure to obtain a preflight weather briefing and to properly evaluate existing weather conditions, as well as reported unfavorable weather conditions such as turbulence, snow, rain, and obscuration at flight altitudes along the route.