K 8 B-Absturz im Wald am Grenchenberg während Hangflug am 18. Juni 1972
Am 18. Juni 1972 startete der Pilot mit dem Segelflugzeug K8B HB-884 vom Flugplatz Grenchen. Nach 9 Minuten im Flugzeugschlepp und erfolgreichem Hangsegeln verlor das Flugzeug plötzlich an Höhe. Das Flugzeug stürzte um 1435 Uhr in den Wald, blieb jedoch ohne Verletzungen für den Piloten. Die Untersuchung ergab, dass ungenügende Geschwindigkeit und falsche Steuerführung zur Ursache des Unfalls führten.
- Ridge soaring flight: After aerotow from Grenchen, the pilot released at 1200 m QFE and spent over two hours ridge soaring along the south slope of the Grenchenberg at about 750 m QFE.
- Low airspeed: During the ridge flight the glider was being flown at a speed that was probably insufficient for the conditions, later estimated by the pilot at about 75 km/h.
- Traffic proximity: Approximately ten gliders were operating in the same area, and shortly before the upset the pilot encountered another K 8 at the same height about 100 m to his left on opposing course.
- Uncommanded right turn: Shortly after continuing straight ahead to avoid the opposing K 8, HB-884 suddenly rolled and turned to the right to about 30° of bank, likely influenced by a gust as reported by the pilot.
- Ineffective correction: The pilot attempted to stop the right roll with a brief control input to the left, but this did not restore normal attitude.
- Turn toward slope: The pilot then decided to continue the unintentional right turn toward the hillside, during which the glider lost height rapidly while close to the wooded slope.
- Crash - no injury: The right wingtip struck treetops and the glider crashed into the forest, heavily damaging the aircraft while the pilot remained uninjured.