Mid-air collision between ASK 23 and Mirage over Grenchenberg, Switzerland

On June 26, 1995, an Alexander Schleicher ASK 23 collided mid-air with a Mirage military aircraft over Grenchenberg, Switzerland. The ASK 23 was on a local training flight, while the Mirage was conducting a military reconnaissance mission. Both pilots were aware of each other's presence but were unable to avoid the collision due to high speeds and limited visibility. The ASK 23 sustained damage to its underside and control systems, but the pilot managed to land safely. The Mirage also suffered minor damage but returned to base without further incident. No injuries were reported.

1. Aerotow local flight: The ASK 23B was aerotowed from Grenchen for a local training soaring flight and released at about 1600 m MSL between Grenchenberg and Hasenmatt.
2. Busy soaring area: Multiple gliders were operating in the Solothurn Jura between Chasseral and Weissenstein, a common 'soaring corridor' on such days, increasing traffic density.
3. High-speed Mirage survey: A Mirage RS was conducting infrared photo survey lines at about 4000 ft in the same area at roughly 700 km/h with significant bank angles and limited forward visibility from the cockpit.
4. Low glider conspicuity: The modern white ASK 23B presented a very slim frontal silhouette that was difficult to detect visually against the horizon.
5. Mirage turns toward glider: While the glider was cruising westward back toward Grenchenberg, the Mirage, previously seen flying west–east at similar altitude, suddenly entered a left turn northbound toward the glider with a large bank angle.
6. Pilot pulls up: Seeing the Mirage rapidly closing with little time to react, the glider pilot instinctively raised the nose in an attempt to avoid collision.
7. Mid-air collision: The two aircraft made a glancing mid-air contact that split the underside of the glider’s fuselage and bent a control pushrod, but the glider remained controllable and the pilot landed safely back at Grenchen with no injuries.