What happened
During the final approach to the destination airport, the aircraft was observed on the runway approach with flaps fully extended but the landing gear in the retracted position. Upon touchdown, the flaps and the cabin entry step made contact with the runway pavement. Following this, engine power increased and the nose of the aircraft pitched downward, causing the propeller to strike the runway.
The aircraft then climbed and banked to the left, striking several trees located approximately 500 feet before the departure end of the runway. The flight continued upward before the aircraft descended into another group of trees located roughly one-half mile from the airport. At the time of this second impact, the aircraft was in a nose-up attitude with the landing gear extended.
The investigation
An examination of the aircraft following the accident revealed no evidence of any mechanical malfunction or failure occurring prior to the impact.
Findings
Investigators detected diphenhydramine, an over-the-counter antihistamine used for allergy symptoms, in the pilot's blood, which was consistent with recent ingestion. In standard doses, this medication is known to cause drowsiness and can affect the performance of complex motor and cognitive tasks.