Background
On 7 May 2013, a Pilatus PC-6/B2-H4, registration HB-FKT, operated by Air Sarina AG, was conducting training flights on the Trient glacier in Switzerland. The aircraft was piloted by an instructor accompanied by a student pilot.
Flight Sequence
The aircraft first departed from the Trient glacier at 13:05 with the instructor, student, four passengers, and equipment. It landed at Bex airfield (LSGB), where the passengers and equipment disembarked. The aircraft then took off again with only the instructor and student on board, returning to the Trient glacier area.
Upon arrival, the instructor noted diffuse light conditions. After two reconnaissance overflights, he decided to perform the landing himself. The first approach and landing were normal, but the aircraft could not stop at the intended point without using reverse thrust. The instructor then took off again to position for a landing that would allow engine shutdown.
During the second approach, shortly before touchdown, the instructor experienced a lack of visual references due to the diffuse light. The aircraft stalled, and the crew felt a firm contact with the ground. The landing then proceeded normally until the aircraft reached the desired position, where it was stopped and the engine shut down.
Investigation Findings
The investigation determined that the accident was caused by a hard landing resulting from a stall at low altitude under diffuse light conditions.