Accident
During an instrument landing system (ILS) approach to runway 27R at metro Oakland International Airport, the pilot of a single-engine aircraft was cleared for the approach. Air traffic control (ATC) observed the aircraft descending through 2,900 feet mean sea level (MSL) and issued a low altitude alert, noting that the aircraft should be at 3,300 feet. The pilot acknowledged with "thank you." ATC then instructed the pilot to climb to 3,300 feet immediately and subsequently canceled the approach clearance, again ordering an immediate climb to 3,300 feet. The aircraft crashed approximately 15 miles east of the airport, impacting a 1,500-foot ridge at about the 1,000-foot level. The pilot, the sole occupant, was killed.
Examination of the wreckage revealed no pre-impact failure or malfunction of the aircraft or its systems.
Probable Cause
The official investigation determined the probable cause of the accident was the pilot's failure to properly follow instrument flight rules (IFR) procedures by not maintaining the minimum descent altitude for that segment of the approach. Related factors included low ceiling, fog, and mountainous terrain.