What happened
On 10 December 2019, a Boeing 747-400F, registration 9V-SFO, was performing a scheduled cargo flight from Sydney to Auckland. During the approach to Runway 05R, the pilot-in-command transitioned from autopilot to manual flight to manage a crosswind of approximately six to seven knots. The pilot utilized a 'touchdown-in-a-crab' technique, intentionally aiming for the right side of the runway centerline to maintain a safety margin from the left edge.
Upon touchdown, the aircraft's speedbrakes deployed automatically. Due to constant control column input and the deployment of these brakes, the aircraft's pitch increased. The pilot, perceiving a bounce and losing sight of runway end lights, believed the aircraft had become airborne and was drifting toward the right edge of the runway. In an attempt to execute a go-around and realign the aircraft, the pilot applied significant left aileron. This maneuver caused the aircraft to bank approximately 7 degrees to the left, resulting in the No. 1 engine scraping the runway surface. Air traffic controllers observed sparks emanating from the left wing during the maneuver. The crew successfully completed the go-around and landed later without further incident.
The investigation
The investigation examined the aircraft's flight data, including the Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR). Investigators analyzed the aircraft's flight control systems and found no mechanical defects in the ailerons, rudder, or elevators. The study also reviewed the pilot's training history and the operator's Flight Data Analysis Programme (FDAP). It was noted that while the pilot was trained in various crosswind techniques, he had not previously demonstrated the 'touchdown-in-a-crab' technique during simulator evaluations.
Findings
- The aircraft's pitch increased following touchdown because of the interaction between constant control input and the automatic deployment of speedbrakes.
- The pilot experienced a sensory illusion where the aircraft appeared to bounce, though FDR data confirmed the aircraft remained on the ground.
- The engine ground strike was caused by the pilot applying left aileron to realign the aircraft during the go-around, which induced a bank angle sufficient to contact the runway.
- The pilot's decision to land off-center increased the risk of an excursion from the right side of the runway.
- The operator's FDAP was not configured to capture all significant rolling events, as it only flagged rolls exceeding 9 degrees occurring within 10 seconds of touchdown.
Safety action
Following the investigation, the operator implemented several changes:
- The threshold for capturing abnormal roll in the FDAP was reduced from 9 degrees to 7 degrees for aircraft below 10 feet, regardless of the timing relative to touchdown.
- A new requirement was established for pilots to demonstrate proficiency in all three manufacturer-recommended crosswind landing techniques during simulator checks.