What happened
On the afternoon of 5 October 2005, an Aerospatiale-Alenia ATR 72-212A, registration ZK-MCJ, was completing a scheduled flight from Christchurch to Queenstown Aerodrome. The flight, operated by Mount Cook Airline, carried 47 passengers and 3 crew members, along with a maintenance engineer.
As the aircraft approached runway 23, the pilots were aware of significant wind conditions, including reports of wind shear and increasing gusts. The aircraft touched down smoothly within the touchdown zone and aligned with the runway centerline. However, shortly after the wheels made contact with the pavement, a sudden, powerful gust of wind struck the aircraft. This gust caused the plane to weathercock aggressively toward the left.
Unable to maintain the centerline, the aircraft drifted off the runway and onto the adjacent grass. The aircraft traveled approximately 630 metres through a soft, muddy area alongside the runway before eventually re-entering the paved surface and taxiing back to the terminal. There were no injuries and no damage to the aircraft.
The investigation
Investigators examined the flight data, cockpit voice recordings, and meteorological reports to understand why the aircraft could not be recovered. The investigation focused on the aircraft's behavior during the landing roll and the effectiveness of the steering controls. Air traffic controllers observed that the aircraft appeared to have very little weight on its nose wheels during the landing phase, which hindered directional control.
Findings
- A strong wind gust, which likely exceeded the aircraft's demonstrated crosswind limit, caused the plane to veer sharply toward the runway edge.
- The effectiveness of the nose wheel steering was significantly reduced because the first officer had not moved the control column far enough forward to ensure sufficient weight was pressing the nose wheels onto the ground.
- The captain's decision to hand over control of the column to the first officer early in the landing roll may have contributed to the lack of necessary steering input.
- The operator's training programs had not sufficiently prepared pilots for the specific challenges of operating the ATR 72 in high crosswind conditions.
Safety action
Following the incident, the Commission issued recommendations to the operator to enhance its training and operational procedures. These included ensuring that transition and recurrent training programs adequately prepare pilots for crosswind operations up to the aircraft's limits and establishing a requirement for the pilot flying to remind the pilot not flying of the necessary steering techniques during strong crosswind landings.