What happened
On 14 January 2015, a Jet Airways Boeing 737-800, registration VT-JGE, was operating a scheduled passenger flight from Mumbai to Kolkata. During the landing phase at Netaji Subhas Chandra Bose International Airport, the aircraft experienced a tail strike on Runway 19L.
The flight crew had initially utilized a dual autopilot approach due to reduced visibility, which was approximately 800 meters at the time. The pilot in command transitioned to manual control at a radio altitude of 161 feet, significantly lower than the recommended 300 to 600 feet. During the landing sequence, the aircraft's speed dropped to 10 knots below the selected Vref. The subsequent flare lasted approximately 14 seconds, far exceeding the standard 4 to 8-second duration. While the aircraft initially touched down at a pitch of 5.1°, the pitch increased to 9.14° shortly after, causing the aft fuselage and tail skid to contact the runway.
The investigation
An inquiry conducted by the AAIB established that the aircraft was airworthy and properly maintained, with all necessary certificates valid. The investigation focused on the flight data recorder (DFDR) and cockpit voice recorder (CVR) to analyze the flight path and crew actions.
Investigators examined the aircraft's stabilizer trim settings, noting that the autopilot had automatically applied nose-up trim during the approach. The analysis revealed that the pilot's attempt to apply nose-down trim after disengaging the autopilot was insufficient to compensate for this trim change. Additionally, the investigation reviewed the physical damage to the aircraft, which included abrasions to the tail skid and the aft belly of the fuselage, as well as sheared rivets and a cracked shear tie.
Findings
- The primary cause of the incident was a decrease in airspeed below Vref combined with an excessive increase in pitch attitude during the landing flare.
- The pilot disengaged the autopilot at 161 feet, which was too low to properly establish manual control before the flare.
- The flare duration of 14 seconds was nearly double the normal operational parameters.
- The crew failed to adequately compensate for the nose-up stabilizer trim applied by the autopilot during the approach.