What happened
On April 17, 1966, at approximately 14:15 CEST, a Ka-8 glider, registration HB-622, was engaged in thermal soaring near the Birrfeld airfield. The flight began at 12:41 CEST. As a cold front moved through Central Switzerland, bringing strong local north winds, the pilot attempted to return to the airfield to land. Due to the intensifying winds, the pilot was unable to reach the runway and was forced to perform an outlanding approximately 500 meters south of the airfield.
During the final approach, while attempting to maneuver for landing in front of an electrical power line at a low altitude, the aircraft experienced a sudden drop in airspeed. This loss of speed caused the glider to stall and drop approximately 4 meters above the ground, resulting in a hard impact.
The investigation
The investigation focused on the circumstances surrounding the forced landing and the sequence of events leading to the impact. Investigators examined the meteorological conditions, noting a West wind pattern across Central Europe and the passage of a cold front through the region. The inquiry also reviewed the pilot's flight path and the aircraft's performance during the low-altitude maneuver near the electrical lines.
Findings
- The primary cause of the accident was that the pilot allowed the airspeed to decrease too significantly during the outlanding procedure at a low altitude.
- The arrival of a cold front created strong, localized north winds that prevented the pilot from reaching the Birrfeld airfield.
- The impact resulted in substantial damage to the wing attachment point on the fuselage.