HBV Diamant incident during Swiss gliding championship near Trimbach
On May 24, 1972, a HBV Diamant experienced an incident near Trimbach, France, during the Swiss gliding championship. The pilot, participating in a 145 km triangular race, struggled to find lift and decided to perform an outlanding. While maneuvering for landing, the glider stalled and crashed, resulting in severe injuries to the pilot and destruction of the aircraft. The investigation confirmed that the accident was caused by the glider's speed dropping below the minimum required during the landing turn.
- Cross-country task flight: During a competition cross-country task, the pilot flew the HBV Diamant after aerotow launch from Grenchen and was returning from the first turnpoint.
- Unable to find lift: On the return leg near Barmelweid, the pilot had difficulty finding usable updrafts and began losing height.
- Continued flight low: Hoping to find lift near Trimbach, the pilot continued south of the Dottenberg toward the southwest, progressively losing more altitude.
- Insufficient height for airfield: The remaining altitude became insufficient to reach Olten airfield, forcing the pilot to plan an outlanding on a relatively small, high-grass field near Trimbach.
- Outlanding setup: The pilot selected a grass field at Grossfeld, flew two full circles to inspect it, and extended the landing gear to commit to the outlanding.
- Stall in landing turn: While turning in a relatively steep right-hand turn onto final approach, the glider’s airspeed dropped below minimum and it abruptly stalled, possibly influenced by strong gusts.
- Crash - serious injury: The glider entered a steep dive with about 45° bank and impacted the ground roughly 15 m short of the chosen field, seriously injuring the pilot and destroying the aircraft.