What happened
On July 19, 1969, at approximately 16:55, a SHK 1 glider, registration D-8385, was performing low-altitude circling maneuvers near the Corvatsch cable car mountain station. The pilot had been utilizing thermal lift to gain altitude earlier in the flight but encountered a loss of lift while flying near the ridge.
While attempting to maneuver away from the dangerous cables of the Corvatsch cable car, the pilot increased the bank angle from 30 to 45 degrees while simultaneously pulling back on the control column. This maneuver caused the aircraft to enter a right-hand spin. Although the pilot managed to recover from the spin, the remaining altitude was insufficient to complete the pull-out, resulting in the aircraft striking a snow-covered slope at approximately 100 km/h. The impact caused severe injuries to the pilot and the total destruction of the aircraft.
The investigation
The investigation, conducted in collaboration with the Samedan Cantonal Police, examined the aircraft's condition, the pilot's flight parameters, and the environmental factors. Investigators analyzed the wreckage, finding no evidence of mechanical failure or technical defects. The investigation also reviewed the aircraft's weight and balance, noting that the takeoff weight was approximately 7 kg above the maximum allowable limit, though the center of gravity remained within the permitted range.
Flight data from the onboard barograph indicated a continuous descent in the final five and a half minutes of flight. The investigation also evaluated the aerodynamic limits of the aircraft during banked turns, calculating that the minimum required airspeed for a 45-degree bank was approximately 77.5 km/h, leaving a very narrow margin of safety during the maneuver.