What happened
On November 8, 2017, a SpiceJet Bombardier DHC-8-402 (Q-400), registration VT-SUL, was performing a scheduled flight from Jabalpur to Delhi. During the approach to Runway 27 at IGI Airport, the pilot-in-command disengaged the autopilot at approximately 411 feet above ground level. In the process, the pilot accidentally pressed the Go-Around (GA) button, which caused the Flight Director bars to shift to a 10-degree pitch-up command.
Despite this change in the flight director, the pilot continued a visual approach. During the descent, the aircraft' and power settings fluctuated. While attempting to correct the aircraft's position relative to the glide slope, the pilot reduced power below flight idle. This reduction in thrust led to an increased rate of descent. To compensate for the high descent rate and to flare the aircraft, the pilot increased the pitch attitude to 6.3 degrees. This maneuver, combined with the high descent rate, resulted in a hard landing with a vertical acceleration of 3.77G and a subsequent tail strike.
The investigation
The AAIB investigation examined the flight data recorder, cockpit voice recorder, and the physical damage to the aircraft. Investigators found that the aircraft's aft center fuselage sustained significant damage, including heavy scrape marks, cracks, and buckling of the skin and stringers. The investigation also noted that the pilot had handed over controls to the co-pilot earlier in the flight without specific company authorization. Additionally, it was established that the crew did not notify Air Traffic Control (ATC) of the runway contact following the incident.
Findings
- The primary cause of the incident was an unstabilized approach resulting from improper control handling, specifically the accidental activation of the Go-Around button and the reduction of thrust below flight idle.
- Low visibility (approximately 400 meters) contributed to errors in depth perception during the flare.
- The pilot's focus on maintaining the glide slope led to errors in managing the descent rate and pitch.
- The crew failed to execute a missed approach despite the inadvertent activation of the Go-Around mode.
Safety action
- It is recommended that SpiceJet review its Q400 training programs to emphasize landing techniques and tail strike prevention.
- The airline should reiterate the requirement for crews to report all such incidents to ATC.
- Guidelines should be reinforced to prevent the unauthorized transfer of controls between pilots.