What happened
On the night of 17 December 2022, a SriLankan Airlines Airbus A320-214, registration 4R-ABN, was performing a scheduled landing at Seychelles International Airport (FSIA) following a flight from Katunayake, Sri Lanka. The approach was conducted under challenging meteorological conditions, characterized by heavy rain showers and gusty winds.
The flight crew initially attempted an ILS approach to Runway 31. During this first attempt, the pilot flying disconnected the autopilot at approximately 700 feet, and the pilot monitoring called for a go-around after the aircraft became unstable. On the subsequent approach, the aircraft began to deviate from the centerline at roughly 400 feet. During the flare, the aircraft drifted toward the right side of the runway. Although the pilot flying attempted to land the aircraft, the aircraft touched down significantly right of the centerline. During the rollout, the aircraft skidded toward the right edge of the runway, with the right main landing gear reaching approximately 6 meters onto the unpaved shoulder, causing damage to two runway edge lights.
The investigation
The investigation, conducted by the Civil Aviation Authority of Sri Lanka, examined flight data from the Digital Flight Data Recorder (DFDR) and cockpit voice recordings. The analysis focused on the aircraft's flight path, the impact of wind reconstruction, and the crew's adherence to Standard Operating Procedures (SOPs).
Investigators reconstructed the wind conditions, finding that between 1000 feet and touchdown, the aircraft encountered a left crosswind component varying between 2kt and 21kt. The investigation also reviewed the crew's use of reverse thrust and rudder inputs. It was noted that the use of maximum reverse thrust during the lateral deviation may have contributed to the instability of the airflow around the rudder, reducing its effectiveness.
Findings
- The primary cause of the deviation was a commanded right roll angle maintained for approximately 21 seconds prior to touchdown.
- A pitch-up command at 110 feet caused the aircraft to float at 50 feet, increasing its exposure to lateral wind forces.
- The pilot flying failed to follow established procedures regarding the flare and touchdown, specifically allowing the aircraft to float and avoiding forward stick movement.
- The crew did not follow the Flight Crew Training Manual (FCTM) recommendation to use reverse thrust at idle rather than maximum reverse during a lateral control problem, as maximum reverse can destabilize rudder efficiency.
- The runway surface was wet due to heavy rain, which contributed to the aircraft's tendency to skid during the rollout.