Background
The accident involved a noninstrument-rated commercial pilot who departed in visual flight rules (VFR) conditions at twilight. The pilot was working toward an instrument rating but was not yet qualified to fly solely by reference to instruments, according to a flight instructor.
Accident Sequence
En route, the pilot encountered marginal VFR conditions. Radar data indicated that the aircraft made a gradual left turn toward rising terrain as it entered an area of poor weather. The aircraft subsequently flew into rising wooded terrain at an elevation of about 1,600 feet, near the top of a mountainous ridge.
Witnesses located in a sparsely inhabited rural area, approximately 3 miles from the accident site, reported that the light condition was "pitch black" when the aircraft flew low over their location. They stated that instrument meteorological conditions (IMC) prevailed. "Torrential" rains had just ended at their location but continued in the area where the aircraft impacted the terrain.
Findings
No preaccident mechanical malfunction of the aircraft was found. However, another pilot who had flown the aircraft recently stated that the heading indicator would precess 30 degrees in 10 minutes.