1974 L-13 Blanik D-1160 accident at Muottas Muragl

Overview and probable cause On 2 August 1974, the L-13 Blanik glider D-1160 crashed at Muottas Muragl in the Swiss canton of Graubünden during a training flight. The aircraft struck the ground at 1536 local time after pitching forward at low altitude. The front-seat pilot was killed, and the rear-seat pilot was seriously injured. The glider was destroyed. The investigation identified the probable cause as the aircraft falling below minimum airspeed at low altitude. Strong turbulence in the accident area and possibly unclear command authority on board may have contributed to the accident. ## Flight and investigation The accident occurred during a gliding camp in Samedan by members of Flugsportverein Herrenberg e.V. from West Germany. The two pilots took off in a winch tow at 1427. The winch cable was released at about 550 m above ground. Witnesses described the final part of the flight at low altitude before the aircraft descended steeply. The accident site was at 2450 m elevation. The preliminary investigation was conducted with the public prosecutor and the Graubünden cantonal police, and the investigation was completed on 7 July 1975. ## Aircraft and conditions The aircraft was a 1972 L-13 Blanik, a two-seat shoulder-wing glider with Fowler flaps and a retractable central wheel, owned by Flugsportverein Herrenberg e.V. Its total operating time before the accident was 301 hours. Weight and center of gravity were within limits. Meteorological data indicated strong cloud cover, visibility of 15–20 km, and winds from the southwest. A helicopter pilot reported strong turbulence during approach to the accident site. No flight recorder was installed or required.