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Accident description
Last updated: 17 November 2017
Status:Final
Date:Monday 2 April 1956
Time:08:10
Type:Boeing 377 Stratocruiser 10-30
Operator:Northwest Orient Airlines
Registration: N74608
C/n / msn: 15954/50
First flight: 1949-10-10 (6 years 6 months)
Total airframe hrs:18489
Engines: 4 Pratt & Whitney R-4360-B6
Crew:Fatalities: 1 / Occupants: 6
Passengers:Fatalities: 4 / Occupants: 32
Total:Fatalities: 5 / Occupants: 38
Airplane damage: Damaged beyond repair
Location:8,7 km (5.4 mls) SW off Seattle/Tacoma International Airport, WA (SEA) (   United States of America)
Phase: En route (ENR)
Nature:Domestic Scheduled Passenger
Departure airport:Seattle/Tacoma International Airport, WA (SEA/KSEA), United States of America
Destination airport:Portland International Airport, OR (PDX/KPDX), United States of America
Flightnumber: 2
Narrative:
Northwest Flight 2 (Seattle-Portland-Chicago-New York) took off from Seattle at 08:06. As the aircraft reached 2000 feet, at 145 knots airspeed, the flaps were retracted. Severe buffeting started and the aircraft tended to roll to the left. Thinking it was an asymmetric flap condition, the captain reduced power to stop the buffeting, but of no avail. Full power was applied again and plans were made to divert to McChord AFB. The plane continued to lose altitude and was not able to reach McChord. A ditching was carried out in Puget Sound. The aircraft sank 15 minutes after the ditching. It appeared that the aircraft had taken off with the engine cowl flaps fully open. Though not emphasized as a contributory factor, it must be noted that the cowl flap control on the Boeing 377 and Lockheed L-1049 move in opposite directions for the closing of the cowls. Most of the flight engineers flying time had been on L-1049 and DC-6 aircraft.

Probable Cause:

PROBABLE CAUSE: "The incorrect analysis of control difficulty which occurred on retraction of the wing flaps as a result of the flight engineer's failure to close the engine cowl flaps - the analysis having been made under conditions of great urgency and within an extremely short period of time available for decision."

Classification:
Ditching

Sources:
» ICAO Accident Digest No.8, Circular 54-AN/49 (72-75)


Photos

photo of Boeing 377 Stratocruiser 10-30 N74608
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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 Seattle/Tacoma International Airport, WA to Portland International Airport, OR as the crow flies is 207 km (129 miles).
Accident location: Approximate; accuracy within a few kilometers.

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Boeing 377

  • 56 built
  • 5th loss
  • 5th fatal accident
  • 3rd worst accident (at the time)
  • 4th worst accident (currently)
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