Event Overview
On July 29, 2014, at about 2240 Pacific daylight time, United Airlines flight 345, a Boeing 757-222 registered as N553UA, experienced a tailstrike while landing at San Diego International Airport (SAN), San Diego, California. The flight carried 174 persons onboard, none of whom were injured. The airplane sustained substantial damage. The flight operated under 14 Code of Federal Regulations Part 121 as a regularly scheduled passenger flight from George Bush Intercontinental Airport (IAH) in Houston, Texas, to SAN.
Flight Sequence
The first officer was the pilot flying, and the captain was the pilot monitoring. This accident flight was the second flight of the day for both crew members. The climb, cruise, and descent phases were uneventful. The aircraft was configured for a flaps 30 landing with the autopilot disengaged for a visual approach to runway 27. The target airspeed was 130 knots, which is 5 knots above the reference landing speed (VREF).
An airplane performance study based on flight data recorder data showed that the wind remained constant during the final descent, with a headwind component of about 4 knots. At approximately 50 feet radio altitude, the first officer began to gradually pull back on the control column, resulting in an elevator deflection of 12 degrees airplane nose-up at touchdown. Touchdown occurred with a sink rate near zero, a pitch attitude of about 6 degrees, and an airspeed of 120 knots—5 knots below VREF.
Post-Touchdown Events
After touchdown, thrust was commanded to idle, and the speedbrakes deployed. The first officer then began to gradually release column backpressure; however, the pitch attitude continued to increase toward the gear-struts-compressed tail strike pitch attitude. The pitch attitude eventually exceeded the gear-struts-compressed tail strike attitude of 10.5 degrees. The first officer commanded reverse thrust as the tail strike occurred and then increased to maximum reverse thrust after derotation had taken place.
Published Flight Operations Technical Bulletins issued by the manufacturer in 1988 and 1990 instructed pilots to immediately lower the nose after touchdown (i.e., apply forward pressure) and warned that reducing airspeed below VREF prior to touchdown would increase body attitude and thereby raise the likelihood of a tail strike. In this accident, touchdown occurred about 5 knots below VREF, and the nose-up elevator input remained for nearly 3.5 seconds, causing the aft fuselage to contact the runway.
Aircraft Damage
Inspection of the airplane revealed substantial abrasion damage to two aft, lower skin panels spanning an area approximately 4 feet long by 1.5 feet wide. Additionally, the forward and aft lower chords on the aft pressure bulkhead were deformed, and the lower aft pressure bulkhead web was buckled.