Date & Time: Apr 20, 1953 at 2308 LT
Type of aircraft:
Douglas DC-6
Operator:
Registration:
N91303
Survivors:
Yes
Schedule:
Los Angeles – San Francisco – Oakland
MSN:
43823
YOM:
1952
Flight number:
WA636
Crew on board:
5
Crew fatalities:
4
Pax on board:
5
Pax fatalities:
4
Other fatalities:
0
Total fatalities:
8
Captain / Total flying hours:
11500
Captain / Total hours on type:
79
Copilot / Total flying hours:
3100
Copilot / Total hours on type:
38
Aircraft flight hours:
826
Circumstances:
The four engine aircraft left San Francisco Airport at 2305LT on a VFR flight to Oakland, distant of 10 miles. At this time, weather conditions were considered as good. On approach to Oakland runway 27R, the pilot-in-command descended below the minimum safe altitude of 500 feet when the aircraft hit the water, exploded and sank into the Bay of Oakland. A stewardess and a passenger were rescued while eight other occupants were killed.
Probable cause:
The Board determines that the probable cause of this accident was the pilot’s action in continuing descent below the 500-feet prescribed minimum altitude until the aircraft struck the water. A probable contributing factor to the aircraft striking the water was the sensory illusion experienced by the pilots. The following findings were pointed out:
- The reported weather conditions at San Francisco and Oakland at the time of departure were above the prescribed minima,
- Actual weather conditions over the Bay at the time and place of the accident were later determined to be below the prescribed minima for trans-bay clearance,
- The pilot of the aircraft failed to comply with the instructions provided in the Visual Trans-Bay procedures which are to be followed in case ceiling and/or visibility below prescribed minima are encountered en route,
- No evidence was found of mechanical malfunction of the aircraft or any of its components recovered,
- The flight descended below minimum specified altitude in an attempt to maintain visual reference.
Final Report:
N91303.pdf654.58 KB