What happened
On June 4, 2018, a student pilot was conducting a solo training flight in an Aquila AT01, registration HB-SGT, at Wangen-Lachen Airport (LSPV). The flight was part of a final training session prior to a pilot license check-ride, following a completed leg from Lommis.
During the takeoff roll on runway 08, the pilot applied takeoff power and released the brakes. As the aircraft accelerated, the pilot focused on monitoring the airspeed to ensure the aircraft reached 35 knots—a predetermined decision speed representing 70% of the 5-knot rotation speed—to determine whether to abort the takeoff.
While monitoring the digital Garmin G500 instrument, the pilot noticed the aircraft drifting toward the left edge of the runway. Realizing that the deviation could no longer be corrected, the pilot initiated an aborted takeoff by reducing engine power and applying the brakes. The aircraft exited the left side of the runway 170 meters beyond the threshold at a ground speed of 47 knots. During the excursion, the right wing struck a wooden post, causing light damage to the underside of the wing. The aircraft eventually came to a stop in a marshy field 275 meters from the runway threshold. One person on the ground sustained light injuries.
The investigation
SUST examined the mechanical condition of the aircraft and the environmental factors present during the incident. The investigation confirmed that the aircraft's steering and braking systems were in good, functional condition, and there were no signs of pre-existing mechanical defects or propeller ground strikes. Weather conditions were found to be favorable, with nearly windless conditions at the time of the event, ruling out meteorological influences on the loss of control.
Findings
- The primary cause of the excursion was the pilot's focus on airspeed monitoring rather than maintaining directional control on the runway.
- The use of a digital airspeed display on the Garmin G500 required the pilot to fixate on the instrument panel, which limited the perception of the lateral deviation.
- The pilot's decision to abort the takeoff once the deviation became unrecoverable was considered a safety-conscious and appropriate response to the situation.