What happened
On 12 January 2023, an Airbus A330-323X, registered N802NW, was completing a commercial flight from Detroit to Amsterdam Airport Schiphol. During the approach to Runway 22, the aircraft's main landing gear touched down on the grass, approximately 11 metres before the runway threshold. The incident occurred during the early morning hours under challenging weather conditions, including light drizzle, reduced visibility, and strong gale-force winds with severe gusts.
While the aircraft was initially following the Instrument Landing System (ILS) glideslope, the flight crew manually disengaged the autopilot at 240 feet radio altitude. During this manual phase, the aircraft descended below the established glide path. The landing resulted in minor damage to the aircraft, but there were no injuries among the 220 passengers or the 13 crew members on board.
The investigation
The Dutch Safety Board examined several contributing factors, including environmental conditions and technical infrastructure. Investigators analyzed the flight recorders and assessed the suitability of the runway configuration for large aircraft. The investigation also looked into human performance, specifically focusing on the crew's management of the approach and potential fatigue levels. Furthermore, the board reviewed the airport's lighting systems, specifically the Precision Approach Path Indicator (PAPI), to determine if they provided adequate guidance for wide-body operations.
Findings
Several interconnected factors led to the undershoot:
- Manual flight path deviation: After disengaging the autopilot, the captain's manual control allowed the aircraft to descend below the ILS and PAPI glide path.
- Prioritization of speed over path: The crew was preoccupied with managing airspeed to avoid a potential runway overrun, which caused them to lose focus on maintaining the correct descent trajectory.
- Environmental disturbances: A wind gust and downdraft encountered at 60 feet above ground level further destabilized the aircraft's flight path.
- Inadequate infrastructure for large aircraft: The ILS and PAPI systems on Runway 22 did not meet ICAO or EASA standards regarding minimum threshold crossing height for Category 4 aircraft, such as the A330.
- Potential fatigue: Evidence suggested that the captain was experiencing significant continuous wakefulness and circadian rhythm effects, which may have impaired decision-making and vigilance.
Safety action
The Dutch Safety Board has recommended that Amsterdam Airport Schiphol restrict the use of Runway 22 for Eye-to-Wheel Height Category 4 aircraft until adjustments are made to ensure sufficient minimum threshold clearance can be achieved.