Accident Sequence
The flight was operating under an instrument flight plan in instrument meteorological conditions (IMC) and was cleared for an instrument approach to South Lake Tahoe Airport, its intended destination. The aircraft departed the initial approach fix on the published transition to the final approach course. Radar contact was lost at 11,400 feet. Subsequently, the aircraft was observed descending out of clouds and maneuvering erratically in visual meteorological conditions (VMC) until it impacted terrain. There was no apparent attempt to recover from the erratic maneuvering.
Medical Findings
Medical records revealed that the pilot had a history of hypertension, hyperlipidemia, and had recently lost 41 pounds on a rigid weight loss program. The autopsy revealed severe arteriosclerosis. Medical records indicated the pilot had been taking Diazide intermittently for several years. Post-accident toxicology results were negative for impairing substances.
Conclusion
The circumstances of the accident, in combination with the pilot's severe diet, medical history, and postmortem examination results, support the conclusion that the pilot became incapacitated in flight.