ASN Aircraft accident Boeing 377 Stratocruiser 10-29 N90943 San Francisco, CA, USA
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Status:Accident investigation report completed and information captured
Date:Tuesday 16 October 1956
Time:06:15
Type:Silhouette image of generic b377 model; specific model in this crash may look slightly different
Boeing 377 Stratocruiser 10-29
Operator:Pan American World Airways (Pan Am)
Registration: N90943
MSN: 15959/36
First flight: 1949-08-02 (7 years 3 months)
Engines: 4 Pratt & Whitney R-4360-B6
Crew:Fatalities: 0 / Occupants: 7
Passengers:Fatalities: 0 / Occupants: 24
Total:Fatalities: 0 / Occupants: 31
Aircraft damage: Damaged beyond repair
Location:1800 km (1125 mls) SW off San Francisco, CA, USA (   Pacific Ocean)
Phase: En route (ENR)
Nature:Domestic Scheduled Passenger
Departure airport:Honolulu International Airport, HI (HNL/PHNL), United States of America
Destination airport:San Francisco International Airport, CA (SFO/KSFO), United States of America
Flightnumber:PA6
Narrative:
PanAm Stratocruiser N90943 was on a round-the-world flight from Philadelphia to San Francisco with stops in Europe, Asia and the Pacific. The aircraft took off from Honolulu at 20:26 HST for the last leg of the flight to San Francisco. The flight was cleared via Green Airway 9, track to 30deg N, 140deg W at FL130 and then at FL210 to San Francisco. About half way, at 01:02 the crew requested a VFR climb to FL210, which was approved. Immediately after reaching this altitude (at 01:19) the no. 1 engine oversped. Reduction of airspeed didn't help and the prop could not be feathered, so the engine was cut. As the aircraft was losing altitude a ditching seemed imminent. US Coast Guard weather station 'November' was contacted at 01:22 about the possible ditching. Climb power was then applied to the remaining engines. The no. 4 engine however, was only developing partial power at full throttle. Despite these problems the crew managed to maintain altitude at 5000 feet at an airspeed of 135 knots. Remaining fuel was insufficient however to reach San Francisco or fly back to Honolulu. The crew decided to orbit the cutter 'November' and wait for daylight to carry out the ditching. Meanwhile electric water lights were laid by the cutter to illuminate a track for the aircraft. At 02:45 the no. 4 engine backfired and failed. The prop was feathered. At 05:40 the captain contacted the cutter again about the intended ditching time and descended to 900 feet. The ditching was carried out at 06:15 with full flaps, gear up and at a speed of 90 knots. The fuselage broke off aft of the main cabin door. The tail section swung to the left, trapping the liferaft launched from the main cabin door. Some 3 minutes after all occupants had been rescued, at 06:32 the aircraft sank at position 30deg01.5'N, 140deg09'W.

Probable Cause:

PROBABLE CAUSE: "An initial mechanical failure which precluded feathering the no. 1 propeller and a subsequent mechanical failure which resulted in a complete loss of power from the no. 4 engine, the effects of which necessitated a ditching."

Accident investigation:

Investigating agency: CAB
Status: Investigation completed
Accident number: final report
Download report: Final report

Classification:
Ditching

Sources:
» ICAO Accident Digest No.8, Circular 54-AN/49 (133-137)


Photos

photo of Boeing-377-Stratocruiser-10-29-N90943
accident date: 16-10-1956
type: Boeing 377 Stratocruiser 10-29
registration: N90943
photo of Boeing-377-Stratocruiser-10-29-N90943
accident date: 16-10-1956
type: Boeing 377 Stratocruiser 10-29
registration: N90943
photo of Boeing-377-Stratocruiser-10-29-N90943
accident date: 16-10-1956
type: Boeing 377 Stratocruiser 10-29
registration: N90943
photo of Boeing-377-Stratocruiser-10-29-N90943
accident date: 16-10-1956
type: Boeing 377 Stratocruiser 10-29
registration: N90943
 

Video, social media

Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Honolulu International Airport, HI to San Francisco International Airport, CA as the crow flies is 3835 km (2397 miles).
Accident location: Exact; as reported in the official accident report.

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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Boeing 377

  • 56 built
  • 6th loss
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