Collision en vol entre ASK 23 et Mirage au-dessus de Grenchenberg, Suisse

Le 26 juin 1995, un Alexander Schleicher ASK 23 est entré en collision en vol avec un avion militaire Mirage au-dessus de Grenchenberg, en Suisse. Le ASK 23 effectuait un vol d'entraînement local, tandis que le Mirage menait une mission de reconnaissance militaire. Les deux pilotes étaient conscients de la présence de l'autre, mais n'ont pas pu éviter la collision en raison des vitesses élevées et de la visibilité limitée. Le ASK 23 a subi des dommages à sa partie inférieure et à ses systèmes de contrôle, mais le pilote a réussi à atterrir en toute sécurité. Le Mirage a également subi des dommages mineurs mais est retourné à la base sans autre incident. Aucun blessé n'a été signalé.

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.