What happened
On February 15, 2015, an Air India Airbus A321, registration VT-PPD, was completing its third flight sector of the day, traveling from Mangalore to Mumbai. The flight, operating as AI-680, carried 187 individuals, including 7 crew members.
During the ILS approach to runway 2 and 7, the aircraft was being manually flown by the First Officer, while the Pilot in Command (PIC) acted as the pilot monitoring. At approximately 40 feet above the ground, the PIC instructed the First Officer to flare and reduce the descent rate. However, the thrust levers remained in the MAX CLIMB detent rather than being moved to the IDLE position. This caused the autothrust system to remain engaged, actively increasing thrust to maintain target speed.
This configuration resulted in a high rate of descent and an initial bounce on the runway. During the bounce, the PIC took control of the aircraft and moved the thrust levers to IDLE, which disengaged the autothrust. In an attempt to manage the descent, the PIC applied a strong nose-up input. This maneuver, combined with the extension of ground spoilers, led to a second, severe hard landing that caused the aircraft's tail to strike the runway.
The investigation
The AAIB India investigation examined the digital flight data recorder (DFDR) and the aircraft's structural condition. Investigators found that while the crew believed the thrust levers had been retarded, the DFDR confirmed they remained at the MAX CLIMB detent during the initial touchdown.
Physical inspections of the aircraft revealed significant structural damage to the aft fuselage, specifically affecting the skin and internal structures at stations 17 and 18. The investigation also noted that several airframe frames were deformed or cracked, and the main landing gear shock absorbers and tires had exceeded their design load limits. The investigation also reviewed the software status of the Spoiler and Elevator Computer (SEC), noting that a planned modification was only partially completed at the time of the incident.
Findings
- The primary cause of the incident was that the thrust levers were not retarded to the IDLE detent during the landing flare, causing the autothrust to maintain high power and a high descent rate.
- The initial bounce was followed by a secondary hard landing caused by the pilot's heavy nose-up input and the subsequent loss of lift following ground spoiler extension.
- The Pilot in Command did not effectively monitor the First Officer's handling of the thrust levers during the landing phase.
- There were no injuries to the 180 passengers or 7 crew members on board.
- The weather, characterized by haze and 4000 meters of visibility, was not a contributing factor to the event.