Accident description
Last updated: 25 October 2014
Status:Final
Date:Sunday 1 December 1974
Time:19:26
Type:Silhouette image of generic B722 model; specific model in this crash may look slightly different
Boeing 727-251
Operator:Northwest Orient Airlines
Registration: N274US
C/n / msn: 20296/777
First flight: 1969-11-25 (5 years )
Engines: 3 Pratt & Whitney JT8D-7B
Crew:Fatalities: 3 / Occupants: 3
Passengers:Fatalities: 0 / Occupants: 0
Total:Fatalities: 3 / Occupants: 3
Airplane damage: Damaged beyond repair
Location:Stony Point, NY (   United States of America) show on map
Phase: En route (ENR)
Nature:Ferry/positioning
Departure airport:New York-John F. Kennedy International Airport, NY (JFK/KJFK), United States of America
Destination airport:Buffalo-Greater Buffalo International Airport, NY (BUF/KBUF), United States of America
Flightnumber:6231
Narrative:
Flight NW6231 departed New York-JFK at 19:14 for a ferry flight to Buffalo and was cleared by departure control to climb to FL140. At 19:21 the flight was cleared to climb to FL310. The aircraft began to climb 2500fpm at an airspeed of 305 knots. As the aircraft climbed through FL160, both the airspeed and the rate of climb began to increase. Reaching FL230, the airspeed had reached 405 knots and the rate of climb had exceeded 6500fpm. The overspeed warning horn sounded a little later, followed 10 seconds later by a stickshaker stall warning. The aircraft then leveled at 24800 feet with a speed of 420 knots until it turned rapidly to the right, 13 seconds later. The airplane started to descend out of control, reaching a vertical acceleration of +5g until it struck the ground in a slightly nose down and right wing-down attitude. The aircraft had descended from 24000 feet to 1090 feet in 83 seconds.

PROBABLE CAUSE: "The loss of control of the aircraft because the flight crew failed to recognize and correct the aircraft's high-angle-of-attack, low-speed stall and its descending spiral. The stall was precipitated by the flight crew'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 flight crew had not activated the pitot head heaters."

Classification:
Icing

Loss of control

Sources:
» Flight International 06.03.1975 (355)
» NTSB Safety Recommendations A-75-27
» NTSB-AAR-75-13

Official accident investigation report
investigating agency: National Transport Safety Bureau (NTSB) - United States of America
report status: Final
report number: NTSB/AAR-75-13
report released:13-AUG-1975
duration of investigation:255 days (8.5 months)
download report: Northwest Airlines, Inc., Boeing 727- 251, N274US, near Thiells, New York, December 1, 1974. (NTSB/AAR-75-13)

Follow-up / safety actions

NTSB issued 3 Safety Recommendations

Show all AD's and Safety Recommendations

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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 New York-John F. Kennedy International Airport, NY to Buffalo-Greater Buffalo International Airport, NY as the crow flies is 480 km (300 miles).

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Boeing 727

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  • 1832 built
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