What happened
On August 18, 1967, a pilot operating a Ka-6 CE Rhönsegler, registration HB-640, departed from Birrfeld airfield to perform a cross-country flight as part of a national gliding competition. The flight plan involved flying to Courtelary and returning to the departure point. While the initial leg of the flight was successful due to favorable thermals, the pilot encountered deteriorating lift conditions along the Jura mountains as the afternoon progressed.
By approximately 17:15, the pilot attempted to land in an open field between Egerkingen and Neuendorf. During the maneuvering process, specifically while turning into the landing direction, the aircraft suddenly pitched forward into a steep, 45-degree dive. The glider struck the ground with its left wing first, followed by a roll, eventually coming to rest upside down. The pilot sustained heavy injuries, and the aircraft was destroyed.
The investigation
Investigators examined the aircraft's maintenance history and the pilot's experience. The Ka-6 CE Rhönsegler was found to be airworthy, with no technical defects contributing to the crash. While a loose camera was found in the cockpit, investigators determined it was unlikely to have interfered with the control column.
The investigation also focused on the pilot's recent training. Although an experienced glider pilot, the pilot had only performed six landings in this specific model prior to the accident. Meteorological data and local witness accounts were analyzed to reconstruct the wind conditions at the time of the accident.
Findings
- The pilot likely underestimated the wind conditions near the ground.
- The aircraft was subjected to turbulent wind shifts, specifically a period of tailwind during the turn into the landing pattern.
- The pilot likely over-controlled the aircraft (pulling back on the stick) due to the visual illusion caused by wind drift, leading to a stall of the inner wing.
- The low altitude at the time of the stall left insufficient margin to recover the aircraft from the resulting dive.