What happened
The pilot was observed taking medication within two hours prior to the flight. A witness identified one of the pills as Darvocet-N 100, noting that she took the same medication. When the pilot started the engine, it revved to a very high RPM, suggesting the throttle was positioned too far open. While taxiing for takeoff, the aircraft nearly collided with a parked plane and veered off the taxiway, coming alarmingly close to a tractor.
During a local flight to a nearby airport at night, the pilot's speech became slurred and erratic. He was unable to locate the destination airport. Tower personnel at the destination identified the aircraft using BRITE radar and could clearly see its lights. They attempted to vector the aircraft to the airport, but the pilot did not follow the directions. Subsequently, the aircraft impacted the ground near the edge of a flooded field while descending with the gear extended, approximately five miles southwest of the airport.
The investigation
An examination of the pilot's gastric contents revealed an unidentified barbituate. His doctor had previously prescribed Talwin and Darvocet-N 100 for back pain. A toxicology check of his blood was negative for drugs, alcohol, and carbon monoxide. There was insufficient urine for a drug check.
Findings
The medication could have caused disorientation and drowsiness in the pilot.