Overview
Recorded radar data indicated that an aircraft was operating in an area characterized by mountainous terrain. Mountain tops in the vicinity were reported to be obscured by clouds. The radar track showed the aircraft initially descending to a low altitude while following a valley, then subsequently climbing until it struck rising terrain at approximately 7,200 feet mean sea level. The wreckage was dispersed over a distance of 300 feet up the mountain slope.
Weather Conditions
At 1000 Pacific Daylight Time, about 32 miles southwest at Bakersfield (elevation 507 feet), the reported weather included scattered clouds at 4,500 feet, an overcast layer at 6,000 feet, visibility of 20 miles, and wind from 260 degrees at 10 knots. Nearby residents reported that the mountain was obscured in clouds at the time of the accident.
Radar Data
Radar information revealed the aircraft's flight path in relation to the terrain. The aircraft flew up a valley at low altitude, then initiated a climb, but the climb was insufficient to avoid contact with the rising terrain at the 7,200-foot level.
Toxicological Findings
Postmortem toxicology tests on the pilot detected a low level of ethanol (23 mg/dL) in a muscle fluid specimen. This was deemed likely attributable to post-mortem production. No ethanol was detected in brain fluid.
Probable Cause
The official probable cause of the accident was VFR flight by the pilot into instrument meteorological conditions (IMC) and his failure to maintain sufficient altitude or clearance from rising or mountainous terrain. Factors relating to the accident were the terrain and weather conditions.