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Last updated: 27 September 2020
Statuts:Enquête Officielle
Date:jeudi 31 mai 1984
Heure:13:34
Type/Sous-type:Silhouette image of generic B722 model; specific model in this crash may look slightly different
Boeing 727-222
Compagnie:United Airlines
Immatriculation: N7640U
Numéro de série: 19913/672
Année de Fabrication: 1968
Moteurs: 3 Pratt & Whitney JT8D-7B
Equipage:victimes: 0 / à bord: 7
Passagers:victimes: 0 / à bord: 98
Total:victimes: 0 / à bord: 105
Dégats de l'appareil: Substantiels
Conséquences: Repaired
Lieu de l'accident:Denver-Stapleton International Airport, CO (DEN) (   Etats-Unis d'Amérique)
Phase de vol: Au décollage (TOF)
Nature:Transport de Passagers Nat.
Aéroport de départ:Denver-Stapleton International Airport, CO (DEN/KDEN), Etats-Unis d'Amérique
Aéroport de destination:Las Vegas-McCarran International Airport, NV (LAS/KLAS), Etats-Unis d'Amérique
Numéro de vol:UA663
Détails:
Before takeoff, the crew of flight UA663 noted cumulus clouds and virga in the area. At 13:27, a de Havilland Canada DHC-7 crew reported a 25 kt loss of airspeed, but several other aircraft then took off without reporting a problem. Due to radio congestion, the captain did not query other aircrews, but decided to climb out at V2 plus 20. when the controller cleared US663 for takeoff, he advised the crew of numerous wind shears in 3 quadrants, but used incorrect terminology in issuing the wind shear alert. During takeoff, the aircraft struck an ILS localizer antenna, 1074 ft from the departure end of the runway, and damaged the lower fuselage. When unable to pressurize the aircraft, the crew returned to the airport and landed.
An investigation revealed the aircraft encountered wind shear from microburst activity which reached its greatest activity as US663 was taking off. The wind sheared from an 8 kt headwind to 40 to 56 kts over a 44 second period. The crew noted a hesitation while accelerating through 120 kts, then at or beyond Vr speed of approx. 141 kts, the aircraft momentarily lost 20 kts.

Probable Cause:

Probable Cause:
weather condition..windshear

Contributing Factors:
object..approach light/navaid
weather condition..rain
weather condition..high wind
weather condition..gusts
weather condition..unfavorable wind
radio communications..excessive
airport/facilities..inadequate
weather evaluation..inaccurate..pilot in command
information unclear..atc personnel(lcl/gnd/clnc)

Accident investigation:
cover
Investigating agency: NTSB
Status: Investigation completed
Accident number: DCA84AA025
Download report: Summary report

Sources:
» NTSB


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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 Denver-Stapleton International Airport, CO et Las Vegas-McCarran International Airport, NV est de 983 km (614 miles).

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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