What happened
On May 19, 2012, at approximately 17:35 local time, an ASW 28-18 glider, registration HB-3393, struck a steep, grassy mountainside at the Falknistürm in the municipality of Maienfeld. The aircraft was participating in the 'Glider Cup' event at the Schänis airfield. After departing via tow, the pilot flew a route toward Klosters. During the final stages of the flight, the aircraft's airspeed decreased significantly, dropping to 75 km/h just before the impact at an altitude of approximately 2,170 meters. The collision resulted in the death of the pilot.
Following the crash, the pilot managed to exit the wreckage and deploy a rescue parachute, eventually seeking shelter under the left wing of the aircraft. However, due to delays in locating the wreckage, the pilot succumbed to his injuries approximately 13 hours after the accident.
The investigation
The SUST investigation examined flight logs, witness statements, and data from the aircraft's FLARM collision warning system. Investigators analyzed the meteorological conditions, noting that the region was experiencing a strong Föhn wind, characterized by significant pressure gradients and gusts up to 30 knots. The investigation also reviewed the pilot's flight history, noting that while he had completed training for this specific aircraft type in 2010, he had a period of inactivity due to professional training and had only performed a few flights in the preceding months.
Findings
- The primary cause of the accident was that the pilot chose an ascending flight path toward a mountain flank while flying in Föhn currents, which led to a loss of control.
- This maneuver induced a stall, making it impossible to recover the aircraft's attitude before hitting the terrain.
- The pilot's limited recent flight training and general flight experience may have hindered an accurate assessment of the environmental risks.
- The search and rescue operation was severely delayed because the aircraft's 121.5 MHz emergency locator transmitter (ELT) was not monitored by satellites, making ground-based triangulation difficult.
- The wreckage was eventually located using data from the FLARM collision warning system rather than traditional emergency beacons.