Overview
On a VFR flight from San Francisco Airport to Oakland, a four-engine aircraft departed at 2305 local time. The distance between the airports is approximately 10 miles. At the time of departure, weather conditions were considered good.
Sequence of Events
As the aircraft approached Oakland runway 27R, the pilot-in-command descended below the minimum safe altitude of 500 feet. The aircraft subsequently struck the water, exploded, and sank into Oakland Bay. A stewardess and a passenger were rescued, while the other eight occupants were killed.
Findings
- Reported weather conditions at San Francisco and Oakland at departure were above the prescribed minima.
- Actual weather conditions over the bay at the time and location of the accident were later determined to be below the prescribed minima for trans-bay clearance.
- The pilot failed to comply with the Visual Trans-Bay procedures, which specify actions to take when ceiling or visibility fall below prescribed minima en route.
- No evidence of mechanical malfunction was found in the aircraft or any of its recovered components.
- The flight descended below the minimum specified altitude in an attempt to maintain visual reference.
Probable Cause
The official investigation determined that the probable cause of the accident was the pilot's action in continuing descent below the 500-foot prescribed minimum altitude until the aircraft struck the water. A contributing factor was the sensory illusion experienced by the pilots.