Accident Airbus A320-211 N311US,

ASN Wikibase Occurrence # 321517

Date:	Monday 4 May 2009
Time:	12:18
Type:	Airbus A320-211
Owner/operator:	Northwest Airlines
Registration:	N311US
MSN:	125
Year of manufacture:	1990
Total airframe hrs:	57600 hours
Engine model:	CFMI CFM56-5A1/F
Fatalities:	Fatalities: 0 / Occupants: 154
Aircraft damage:	Substantial, repaired
Category:	Accident
Location:	Denver International Airport, CO (DEN) - United States of America
Phase:	Landing
Nature:	Passenger - Scheduled
Departure airport:	Minneapolis-St. Paul International Airport, MN (MSP/KMSP)
Destination airport:	Denver International Airport, CO (DEN/KDEN)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
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: "The first officers 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 officers delay in retarding the thrust levers to idle, thereby providing residual thrust and preventing spoiler deployment."

Accident investigation: