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Accident
Last updated: 18 October 2017
Statuts:Enquête Officielle
Date:dimanche 1 décembre 1974
Heure:19:26
Type/Sous-type:Silhouette image of generic B722 model; specific model in this crash may look slightly different
Boeing 727-251
Compagnie:Northwest Orient Airlines
Immatriculation: N274US
Numéro de série: 20296/777
Année de Fabrication: 1969-11-25 (5 years )
Moteurs: 3 Pratt & Whitney JT8D-7B
Equipage:victimes: 3 / à bord: 3
Passagers:victimes: 0 / à bord: 0
Total:victimes: 3 / à bord: 3
Dégats de l'appareil: Perte Totale
Conséquences: Written off (damaged beyond repair)
Lieu de l'accident:Stony Point, NY (   Etats-Unis d'Amérique)
Phase de vol: En vol (ENR)
Nature:Convoyage
Aéroport de départ:New York-John F. Kennedy International Airport, NY (JFK/KJFK), Etats-Unis d'Amérique
Aéroport de destination:Buffalo-Greater Buffalo International Airport, NY (BUF/KBUF), Etats-Unis d'Amérique
Numéro de vol:NW6231
Détails:
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:

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."

Accident investigation:
cover
Investigating agency: NTSB
Status: Investigation completed
Duration: 255 days (9 months)
Accident number: NTSB/AAR-75-13
Download report: Final report

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


Opérations de secours

NTSB issued 3 Safety Recommendations

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Plan
Ce plan montre l'aéroport de départ ainsi que la supposée destination du vol. La ligne fixe reliant les deux aéroports n'est pas le plan de vol exact.
La distance entre New York-John F. Kennedy International Airport, NY et Buffalo-Greater Buffalo International Airport, NY est de 480 km (300 miles).
Accident location: Exact; as reported in the official accident report.

Les informations ci-dessus ne représentent pas l'opinion de la 'Flight Safety Foundation' ou de 'Aviation Safety Network' sur les causes de l'accident. Ces informations prélimimaires sont basées sur les faits tel qu'ils sont connus à ce jour.
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Boeing 727

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