Incident Overview
At 2219, the pilot of a general aviation aircraft contacted approach control, reporting his position at 4,500 feet mean sea level over Mt. Diablo. The controller instructed the pilot to cross the east bay shoreline at or above 2,000 feet mean sea level and to remain clear of Class B airspace. At 2228, the controller radioed that contact with the aircraft had been lost; no reply was received from the pilot.
Wreckage Discovery
The aircraft wreckage was located the following morning at the 1,680-foot level of the mountain range. Impact signatures and wreckage distribution indicated that the aircraft had impacted trees while flying almost parallel to a ridgeline with a wings and nose level attitude.
Weather Conditions
The Area Forecast indicated that by 2200, overcast clouds from 1,000 to 1,500 feet above ground level were expected, accompanied by light rain showers and visibility between 3 and 5 statute miles. At 2153, approximately 37 minutes before the accident, a weather reporting facility located 14.9 nautical miles west of the accident site reported overcast clouds at 700 feet. At 2253, approximately 23 minutes after the accident, the same facility reported overcast clouds at 700 feet. Another facility, 10 nautical miles west-southwest of the accident site, reported overcast clouds at 900 feet at 2154 and at 700 feet at 2254. Based on these weather conditions, the mountain ridge where the accident occurred was likely to have been obscured by clouds.
Pilot Actions
A friend of the pilot, who witnessed his departure, reported that the pilot did not obtain a weather briefing before takeoff.
Aircraft Examination
No aircraft or engine anomalies were noted that would have prevented normal operations.