What happened
On 29 July 2014, a Boeing 737-8AS, registration EI-EFB, was performing a commercial passenger flight into Stansted Airport. The flight was conducting an ILS approach for a Flaps 30 landing on Runway 04. At approximately 500 feet, the co-pilot disconnected both the autopilot and autothrottle to continue the approach manually.
During the final 200 feet of the descent, slight wind variations required the pilot flying to apply left aileron. This resulted in the left main landing gear touching the runway first. Following this initial contact, the aircraft bounced a few feet into the air. During this bounce, the thrust levers were moved to the idle position. This action triggered the automatic deployment of the speed brakes.
Approximately three to four seconds after the first touchdown, the aircraft made a second, much heavier impact. During this second touchdown, the aircraft maintained a high nose-up attitude, causing the tail to scrape along the runway. While there were no fatalities or injuries among the 171 passengers and 6 crew members, the impact caused visible damage to the lower rear fuselage skin and the drain mast, including damage to several internal stringers and frames.
The investigation
Investigators examined flight data and technical parameters to determine the sequence of events. The aircraft initially touched down at 144.5 KCAS with a 5.1° nose-up pitch. At the moment of the first touchdown, the engine N1 values were at 59% and 56%, indicating that the engines were still producing significant thrust.
Data showed that the thrust levers were retarded to idle roughly two seconds after this initial contact. Following this reduction in thrust, the speed brake handle moved to the deployed position and the flight spoilers activated. The investigation noted that the aircraft's pitch increased significantly during the second impact, reaching a peak of 8.9° nose up, with a peak normal acceleration of 2.07g.
Findings
- The primary cause of the tailstrike was the automatic deployment of the speed brakes during the bounce, which led to a loss of lift and a nose-up pitching moment.
- The bounce itself was facilitated by the engines remaining at approach power rather than idle during the initial touchdown.
- Retarding the thrust levers to idle while the aircraft was airborne during the bounce satisfied the parameters for automatic speed brake deployment.
- The subsequent heavy landing and tailscrape occurred because the nose-up pitch caused by the spoilers prevented a level touchdown.