What happened
On May 18, 2003, a student pilot was conducting training maneuvers near Gudo, Switzerland. Earlier that day, the student had completed a dual-instruction flight in an ASK 21. Following that flight, the student overheard instructors discussing different thermal locations for subsequent training sorties. Misinterpreting these discussions, the student believed they were tasked with flying toward the Monti di Medeglia region, rather than the intended Monti di Motti area.
After being towed into the air, the student performed several maneuvers in a thermal before moving toward the Monti di Gudo area in search of better lift. While executing a 180-degree right turn, the pilot became distracted by an alpine pasture to the left and failed to notice the proximity to the mountain ridge. An unexpected wind shear caused the right wing to drop approximately 55 degrees. In an attempt to correct the movement, the pilot applied an abrupt left control input, which led to a loss of control. The Schleicher Ka-8B, registration HB-734, struck the rocky terrain with its right wingtip before coming to rest wedged between two coniferous trees. The aircraft was destroyed, though the pilot escaped the wreckage uninjured.
The investigation
SUST examined the pilot's flight history and the aircraft's condition. The investigation established that the student pilot had limited experience, having only completed a transition to the Ka-8B model in January 2003 and having not flown this specific aircraft, HB-734, for several months prior to the accident. The investigation also noted that the pilot was wearing a parachute and a four-point harness, both of which functioned correctly during the impact. The aircraft was found to be properly configured, with the weight and balance within limits and all structural pins correctly secured. However, the aircraft was not equipped with a GPS or an altimeter.
Findings
- The primary cause of the accident was the pilot losing control of the glider during low-altitude thermal flight.
- A misunderstanding of the flight assignment led the pilot to fly toward the wrong geographic area.
- The pilot's limited flight experience contributed to the inability to manage the unexpected wind shear and the subsequent improper control input.