What happened
On September 1, 2018, an Airbus A320 aircraft, registration VT-WGJ, operated by Go Air, was involved in a serious incident during a flight from Bangalore to Pune. Shortly after takeoff, the aircraft experienced extreme vibrations in engine number one, reaching the maximum displayable level of 10 units. As the aircraft climbed, the crew encountered several warnings, including oil filter degradation and an engine stall, eventually leading to the failure of engine number one.
The flight crew decided to return to Bangalore, declaring a PAN PAN call. During the descent and subsequent manual approach, the aircraft entered a low-energy state, characterized by multiple "SPEED SPEED" and "GLIDESLOPE" warnings. The aircraft was significantly below the glidepath and flying below the minimum selectable speed. During the final stages of the landing, the pilot flying applied continuous full back-stick inputs. This caused the aircraft to pitch up to 10 degrees, triggering the Angle of Attack protection. The aircraft subsequently made a severe hard landing with a computed vertical load of 3.25g, exceeding manufacturer limits.
The investigation
AAIB India examined the Digital Flight Data Recorder (DFDR) and Cockpit Voice Recorder (CVR) to reconstruct the flight sequence. The investigation focused on the engine's mechanical failure, the crew's management of the automation, and the stability of the approach. Analysis of the DFDR data confirmed that the landing exceeded the structural limits of the aircraft. Following the incident, the aircraft underwent extensive structural inspections, and the main landing gears were replaced as recommended by the manufacturer.
Findings
- The engine failure was preceded by high N2 vibrations during the takeoff roll.
- The flight crew failed to set the remaining engine's thrust lever to the MCT detent, which triggered a recurring flashing automation warning.
- The approach was unstabilized, as the aircraft was flying at a speed 18 knots below the minimum selectable speed and was significantly below the glideslope.
- The pilot flying continued the approach despite the low-energy state, and the pilot monitoring did not advise a go-around.
- The hard landing was a direct result of the pilot applying full back-stick inputs while the aircraft was in a low-speed, high-pitch state.