K 8 B crash in forest at Grenchenberg during ridge flight on June 18, 1972
On June 18, 1972, a K8B glider crashed into a forest near Grenchen after experiencing an unintentional right turn. The pilot had launched via tow and was flying at approximately 75 km/h when the incident occurred. Contributing factors included insufficient speed and inadequate control inputs, likely exacerbated by a gust of wind. The pilot remained uninjured, but the glider sustained severe damage.
- 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.