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Last updated: 22 September 2021
Statuts:Enquête Officielle
Date:lundi 4 mai 2009
Heure:12:18
Type/Sous-type:Silhouette image of generic A320 model; specific model in this crash may look slightly different
Airbus A320-211
Compagnie:Northwest Airlines
Immatriculation: N311US
Numéro de série: 0125
Année de Fabrication: 1990
Heures de vol:57600
Moteurs: 2 CFMI CFM56-5A1/F
Equipage:victimes: 0 / à bord: 7
Passagers:victimes: 0 / à bord: 147
Total:victimes: 0 / à bord: 154
Dégats de l'appareil: Substantiels
Conséquences: Repaired
Lieu de l'accident:Denver International Airport, CO (DEN) (   Etats-Unis d'Amérique)
Phase de vol: A l'atterrissage (LDG)
Nature:Transport de Passagers Nat.
Aéroport de départ:Minneapolis-St. Paul International Airport, MN (MSP/KMSP), Etats-Unis d'Amérique
Aéroport de destination:Denver International Airport, CO (DEN/KDEN), Etats-Unis d'Amérique
Numéro de vol: 557
Détails:
An Airbus A320-211, registration N311US, operated by Northwest Airlines as flight NW557, experienced a tailstrike resulting in substantial damage upon landing on runway 16L at Denver International Airport, CO (DEN). The flight was a regularly scheduled passenger flight which departed from Minneapolis-St. Paul Airport, MN (MSP) at 11:39.
The flight to the DEN area was reported as routine, with VFR weather prevailing. At about 12:02, as the flight was entering the DEN terminal area, the crew briefed an approach speed of 139 knots for a visual approach to runway 16L. The First Officer (FO) was the pilot flying (PF) and reported the approach was stable at 1,000 feet above the runway threshold. At 12:16:15 ATC cleared the flight to land and issued a wind advisory of 260 degrees at 5 knots. The flight crew extended the gear and selected flaps 3.
The autopilot was disengaged at 12:17:38, at approximately 750 feet above touchdown. The auto-thrust and flight directors were engaged. During the approach, the crew noted that the aircraft was experiencing approximately 7 knots of tailwind, and as the approach progressed FDR data indicated the tailwind component increased to approximately 11 knots.
As the airplane passed approximately 50 feet above touchdown the rate of descent was about 800 feet per minute (fpm). The captain stated he expected nothing more than a firm touchdown. The FO initiated the flare at about 45 feet. He stated that he attempted to arrest the sink rate with larger than normal aft stick deflection. During the flare, passing 20 feet above the runway, the automated "retard" call-out began a sequence of three annunciations. This automatic call-out is designed to remind the pilot to move the thrust levers to the idle detent. The thrust levers remained in the climb detent (CLB).
During the flare, the airplane pitched up to about eight degrees nose up and airspeed decreased to about 132 knots. The airplane touched down on both main landing gear with a vertical load of about 1.56 G. At the time of initial touchdown, the thrust levers were still in CLB, and engine N1 increased from approximately 54% to 64% over 3 seconds.
Radio altimeter values increased, indicating the aircraft then bounced. The FO held 16 degrees aft stick input (approximately full aft travel), and moved the thrust levers to idle during the bounce. Ground spoilers deployed (thrust lever position and wheel spin up logic was satisfied) and the airplane touched down a second time in an eleven degree nose up attitude, with FO still applying full aft stick input. At this point the captain began adding some nose down stick input however pitch attitude continued increasing to about 12.5 degrees nose up. The Airbus FCOM indicates that the max pitch up angle with gear compressed is 11.7 degrees. A "dual input" automatic call-out was recorded, indicating the system detected both pilots making stick inputs, and the sound of a loud bang was heard on the cockpit voice recorder. As the captain stick input moved further forward, in the airplane nose down direction, and the FO stick back pressure relaxed, the airplane began to pitch downward and about 3 seconds after the loud bang the nose wheel touched down. Thrust levers were then moved to the reverse position and autobraking began. The remainder of the roll out was normal.
The aircraft experienced heavy abrasions, dents and perforations of the skin along the lower rear fuselage between frames 62 and 76. Additionally, the aft galley drain mast and two aircraft antennas were broken, and the APU air intake sustained damage. The rear pressure bulkhead damage was buckled and cracked. The lower segment of frame 70 was cracked and had heavy abrasions. Interior damage also consisted of minor deformation of frames, damage to stringers, frame clips, fasteners, floor support strut fittings and flange.

Probable Cause:

PROBABLE CAUSE: "The first officer’s excessive pitch-up of the airplane while landing with a tailwind, which resulted in a tailstrike following a bounced landing. Contributing to the bounced landing were a high descent rate and excessive thrust resulting from the first officer’s delay in retarding the thrust levers to idle, thereby providing residual thrust and preventing spoiler deployment."

Accident investigation:
cover
Investigating agency: NTSB
Status: Investigation completed
Duration: 1 years
Accident number: DCA09FA047
Download report: Summary report

Sources:
» NTSB
» NTSB accident docket


Photos

photo of Airbus-A320-211-N311US
accident date: 04-05-2009
type: Airbus A320-211
registration: N311US
photo of Airbus-A320-211-N311US
accident date: 04-05-2009
type: Airbus A320-211
registration: N311US
photo of Airbus-A320-211-N311US
accident date: 04-05-2009
type: Airbus A320-211
registration: N311US
 

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 Minneapolis-St. Paul International Airport, MN et Denver International Airport, CO est de 1085 km (678 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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