Event Details

Title:In-flight upset, Northwest Airlines, Inc., Boeing 727-251, N274US, Near Thiells, New York, December 1, 1974
Micro summary:Following a high-altitude stall, this Boeing 727 crashed.
Event Time:1974-12-01 at 1926 EST
File Name:1974-12-01-US.pdf
Publishing Agency:National Transportation Safety Board (NTSB)
Publishing Country:USA
Report number:NTSB-AAR-75-13
Site of event:3.2 nmi west of Thiells, NY
Latitude/Longitude:N4112'53" W745'40"
Departure:John F. Kennedy International Airport, Jamaica, New York, USA
Destination:Buffalo Niagara International Airport, Cheektowaga, New York, USA
Airplane Type(s):Boeing 727-251
Flight Phase:Climb
Operator(s):Northwest Airlines
Type of flight:Ferry
Serious Injuries:0
Other Injuries:0
Executive Summary:About 1926 EST on December 1, 1974, Northwest Airlines Flight 6231, a Boeing 727-251, crashed about 3.2 mi west of Thiells, New York. Flight 6231 was a ferry flight to Buffalo, New York. The accident occurred about 12 minutes after the flight had departed John F. Kennedy International Airport, Jamaica, New York. Three crewmembers, the only persons aboard the aircraft, died in the crash. The aircraft was destroyed.

The aircraft stalled at 24,800 feet m.s.l. and entered an uncontrolled, spiralling descent to the ground. Throughout the stall and descent the flightcrew did not recognize the actual condition of the aircraft and did not take the correct measures necessary to return the aircraft to level flight. Near 3,500 feet m.s.l. , a large portion of the left horizontal stabilizer separated from the aircraft, which made control of the aircraft impossible.

The National Transportation Safety Board determines that the probable cause of this accident was the loss of control of the aircraft. because the flightcrew failed to recognize and correct the aircraft's high-angle-ofattack, low-speed stall and its descending spiral. The stall was precipitated by the flightcrew's improper reaction to erroneous airspeed and Mach indications which had resulted from a blockage of the pitot heads by atmospheric icing. Contrary to standard operational procedures, the flightcrew had not activated the pitot head heaters.
Learning Keywords:Operations - Icing
Operations - Upset in-flight (extreme attitudes, stall, spin)
Systems - Flight Instruments
Systems - Pitot/Static System
Consequence - Hull Loss
Close match:Stall on takeoff, Birgenair, Boeing 757, TC-GEN
Loss of airspeed displays, Serious incident, 05.04.1998, near Frankfurt/Main Airport, to an Airbus A320-200
Incorrect airspeed indications, UPS 747-200 at Dublin Airport, May 12, 2000
In-flight loss of both engines, McDonnell Douglas MD-82, June 4, 2002
Runway Overrun Following Rejected Takeoff, Continental Airlines Flight 795, McDonnell Douglas MD-82, N18835, Laguardia Airport, Flushing, New York, March 2, 1994
Stall on takeoff, Air Florida, Inc., Boeing 737-222, N62AF, Collision With 14th Street Bridge, Near Washington National Airport, Washington, D.C., January 13, 1982
Erroneous airspeed indications/stickshaker, Boeing 717-200, VH-NHX, February 28, 2006
Stall in climb, Boeing 757-200, TF-FII, October 20, 2002


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