What happened
On the early morning of 13 October 2006, a BAe Systems ATP, registration SE-LNX, was conducting a freight flight from Umeå to Luleå/Kallax airport. During the approach to runway 32, the aircraft encountered heavy fog with visibility limited to 550 meters.
As the crew transitioned from autopilot to manual control near the ground, they noted a significant discrepancy in power between the two engines, despite the throttles being in identical positions. During the flare, as the pilots reduced power to flight idle, the aircraft began to veer toward the right. The crew attempted to correct the heading with the rudder, but the aircraft drifted toward the edge of the runway, eventually striking a runway edge light. A subsequent inspection of the aircraft revealed damage to one of the right main landing gear tires.
The investigation
The Swedish Accident Investigation Board (SHK) analyzed flight data from the aircraft's flight data recorder (FDR), which revealed substantial fluctuations in pitch and roll during the final stages of the approach. The FDR data confirmed that the right engine was consistently delivering more torque than the left engine throughout the descent.
Investigators also examined the airport infrastructure and the crew's qualifications. The investigation noted that the runway lacked centerline lighting, and the edge lights were positioned four meters outside the asphalt, which exceeded standard regulatory requirements. Furthermore, the investigation reviewed the flight crew's recent training and experience on this specific aircraft type.
Findings
- The primary cause of the incident was the failure to maintain the correct heading during landing. This was driven by asymmetric engine thrust and the limited experience of the pilots on this aircraft type.
- The engine control rigging was found to be incorrect, creating a large power imbalance that increased pilot workload during a critical phase of flight.
- The lack of runway centerline lighting and the non-standard placement of the edge lights prevented the crew from recognizing the lateral deviation in time.
- Both the commander and co-pilot had very limited experience on the BAe Systems ATP, with only approximately three months of operational experience on the type.