What happened
On October 16, 1998, a student pilot was conducting a solo navigation flight from Sion to Ecuvill and arrived at the Ecuvillens airfield for landing. The flight was part of a training program, and the pilot had previously experienced similar difficulties during a landing in Samedan, where the aircraft had also veered off the runway.
During the landing on runway 28, an instructor witnessing the event described the approach as a stabilized, short final, though noted the airspeed appeared high. The aircraft made a very smooth, almost perfect "three-point" touchdown. However, shortly after contact with the ground, the aircraft began a slow rightward turn without any apparent corrective action from the pilot. The aircraft exited the runway, crossed the safety grass, and entered a freshly plowed field. As the aircraft traveled through the soft soil, the nose wheel sank, causing the right wing to strike the ground and the aircraft to capsize onto its nose and propeller.
The investigation
Investigators examined the aircraft, a Robin DR 400-140B, registration HB-KDB, and found no mechanical defects. Specifically, the braking system, which utilized foot-operated brakes rather than the hand-operated brakes found on other similar aircraft used by the student, was inspected and found to be functioning correctly. The aircraft's weight and center of gravity were within prescribed limits.
Physical evidence from the runway showed that the left wheel began to skid approximately 320 meters after the runway threshold, followed by the nose wheel. The tracks left in the plowed field indicated the aircraft initially moved straight, then curved right, and finally curved left as the nose wheel became embedded in the soil. The investigation also reviewed the student's training records, noting that the pilot had previously struggled with the foot-brake system during a flight in September 1998.
Findings
- The primary cause of the accident was the loss of control during the deceleration phase following touchdown.
- The loss of control was likely induced by an incorrect rudder pedal input.
- The student pilot experienced confusion due to the different braking configurations (foot vs. hand brakes) between various aircraft in their training fleet.
- The pilot admitted that when stressed or managing multiple tasks, they had a tendency to apply pressure to the right rudder pedal when the aircraft was already deviating to the right.