ASK 18 crash on Montagne de Romont during training flight
On March 30, 1989, an Alexander Schleicher ASK 18 crashed on Montagne de Romont in Switzerland during a local training flight. The glider, towed by an aircraft from the Grenchen airfield, was not observed after release and subsequently crashed into a wooded slope. The pilot sustained fatal injuries, and the wreckage was discovered two days later by a passerby. The official investigation suggested that the accident was likely due to the pilot not maintaining sufficient safety margins in changing wind conditions.
- Aerotow local flight: The pilot took off from Grenchen by aerotow for a local training flight and released at about 1000–1100 m MSL over the Grenchenberg before beginning ridge flying along the Jura towards the east.
- Limited recent soaring: This was the pilot’s first solo glider flight of the season after a 7‑month break from soaring, with only a brief dual check flight 12 days earlier and modest experience on the ASK 18 type.
- Marginal ridge conditions: Along the Jura the wind was changing from weak southwesterly to bise with sparse and weak lift on the ridge, making height maintenance difficult.
- Insufficient safety margins: While flying near the Jura slope, the pilot did not maintain adequate safety margins in airspeed and/or distance from the terrain under the prevailing variable wind conditions.
- Loss of safe flight path: The inadequate margins led either to encountering sink close to the slope or to an unrecognized low‑speed, over‑banked or stalled condition from which recovery was not possible at the low height above the terrain.
- Crash - fatal: The glider impacted a wooded slope on the Montagne de Romont at about 1130 m MSL, was destroyed, and the pilot sustained fatal injuries.