Primary finding
Probable cause
The first officer’s failure to maintain proper pitch attitude during flare which resulted in a bounced landing and a tailstrike.
Investigator assessment
Analysis narrative
United Airlines flight 2136 sustained a tail strike while landing at Harry Reid International Airport (LAS), Las Vegas, Nevada. The flight was a regularly scheduled domestic passenger flight from Washington Dulles Airport (IAD), Dulles, Virginia to LAS. The airplane sustained substantial damage to the underside of the fuselage near the tail. According to the flight crew, the first officer (FO) was the pilot flying, and the captain was the pilot monitoring when they were cleared to land on runway 26L at LAS. The FO elected to disengage the autopilot and autothrottle at approximately 1,600 feet above ground level (AGL). According to the flightcrew, the airplane was in the landing configuration and during the descent, stabilized approach criteria was met at 1,500 ft., 1,000 ft. and 500 ft. AGL, and the airspeed was close to the correct approach speed. The captain stated he heard the aircraft aural callouts below 50 feet, and upon hearing “20” he felt no column movement indicative of the start of a flare maneuver, and he stated “flare”, and he felt the column begin to move, quickly followed by the “10” callout. Data from the digital flight data recorder (DFDR) showed that about 4 seconds prior to the first touchdown, the control column began to move in the airplane nose up direction, increasing the pitch to 7 degrees as the main gear weight on wheels indicator transitioned to “ground”. The column was pushed forward several degrees as the air/ground indicator returned to “air” and the pitch angle reduced to 3.7 degrees. The column was then moved aft in the airplane nose up direction as the weight on wheels transitioned to “ground” again, and the airplane attained a maximum pitch angle of 8.2 degrees and experienced 2.4g vertical acceleration during the second transition of weight on wheel indicator to “ground”. Both pilots reported feeling a second touchdown. The captain then took control of the aircraft for the exit from the runway. The airplane exited the runway and taxied uneventfully to the gate. Post flight inspection revealed damage to the airplane tail skid assembly and substantial damage to lower fuselage primary structure in the aft portion of the aircraft, requiring replacement of several principal structural elements.