Mid-air collision between Ka 6 and Club Libelle near Münster, Switzerland

On July 18, 1979, a mid-air collision occurred between a Ka 6 and a Club Libelle during a soaring camp near Münster, Switzerland. The Club Libelle was performing tight spirals in strong lift when the Ka 6 entered the same area, resulting in a collision at approximately 2500 meters altitude. The Ka 6 sustained significant damage and made an emergency landing on a rocky slope, leading to the destruction of the aircraft and minor injuries to the pilot. The Club Libelle, despite damage to its left wing, managed to land safely at Münster airfield. The incident was attributed to insufficient airspace observation by both pilots.

1. Aerotow thermaling: During a soaring camp at Münster, the Ka 6 HB-650 launched by aerotow at 1112 and began thermaling in the Alps south of the Galmihornhütte.
2. Shared thermal area: Both the Ka 6 and the Club Libelle were circling in the same general lift area south of the Galmihornhütte, later moving to the strong thermal southeast of the Rossboden with about 200 m lateral separation.
3. Poor lookout: While both gliders circled in right-hand turns with different bank angles and circle sizes, the pilots lost visual contact with each other and did not adequately monitor the surrounding airspace.
4. Conflict in thermal: At about 2500 m MSL southeast of the Rossboden, the flight paths of the two gliders converged such that the Club Libelle approached the Ka 6 from behind and slightly left.
5. Ka 6 avoidance maneuver: Seeing the Club Libelle coming up from behind, the Ka 6 pilot attempted to avoid collision by pushing the nose down and turning away.
6. Mid-air contact: During the avoidance maneuver, the underside of the Club Libelle’s fuselage struck the Ka 6’s horizontal tail and then its left wing hit the Ka 6’s rudder, damaging the empennage.
7. Crash - minor injury: Feeling control stick vibrations after the collision, the Ka 6 pilot extended airbrakes and attempted an emergency landing on a rocky slope, where the glider impacted with the left wing, broke up, and slid 30–40 m down the hill, resulting in destruction of the aircraft and minor injuries to the pilot.