Primary finding
Probable cause
Failure of the pilot to maintain sufficient airspeed to properly flare the airplane during the landing.
Investigator assessment
Analysis narrative
The captain said he flew what he considered to be a normal, stabilized approach, using 28 degrees of flaps and a Vref speed of 133 knots plus 5 knots. He flared the airplane over the runway and realized the sink rate was not being arrested as desired. He made a more 'aggressive' pull on the control yoke while advancing the thrust levers a 'significant amount.' The airplane landed hard, sustaining substantial damage. DFDR readout disclosed that the airspeed remained above Vref+5 knots until, at a radio altimeter altitude of 238 feet, it was 138.75 knots; thereafter, it began to drop. When the airplane touched down on the runway, airspeed was 124.75 knots, and the pitch attitude was 10.62 degrees nose up. There was a +5.54 'G' vertical acceleration spike.
Source record
Factual narrative
On February 4, 1996, at 1647 mountain standard time, a McDonnell Douglas MD-88, N957DL, operated by Delta Air Lines, Inc., as flight 1879, scheduled domestic passenger service under Title 14 CFR Part 121, sustained substantial damage during a hard landing at Denver International Airport. Visual meteorological conditions prevailed at the time, and an IFR flight plan had been filed. The captain, first officer, two flight attendants, and 115 passengers were not injured, but one flight attendant did sustain a minor injury. The flight originated at Dallas-Fort Worth International Airport, Texas, approximately 1 hour, 44 minutes before the accident. According to the captain's statement, he flew what he considered to be a normal, stabilized approach, using 28 degrees of flaps and a VREF speed of 133 knots plus 5 knots. He flared the airplane over the runway and realized the sink rate was not being arrested as desired. He made a more "aggressive" pull on the control yoke while advancing the thrust levers "a significant amount. A very firm touchdown occurred." Examination disclosed damage to the tail bumper and wrinkled skin. Readout of the airplane's digital flight data recorder (DFDR) disclosed subframes 1584 through 1589 contained the accident data, with subframe 1587 containing the runway contact data. The readout showed airspeed remained above VREF+5 up until subframe 1568, when, at a radio altimeter altitude of 238 feet, it was at 138.75 knots; thereafter, it began to drop. When the airplane touched down on the runway, airspeed was 124.75 knots, and the pitch attitude was 10.62 degrees nose up. There was a +5.54 vertical acceleration spike (see attached DFDR factual report). -