What happened
On June 7, 1970, a pilot was participating in a competitive triangle flight as part of the East Swiss Gliding Championships. Flying a Ka 6 CR, registration HB-996, from Schaffhausen airfield, the pilot encountered significantly poor thermic conditions. As the flight progressed through Thayngen and Amlikon, the aircraft was unable to find sufficient rising air, leading to a continuous loss of altitude.
Upon reaching the Wellhausen area, the pilot decided to terminate the competition flight and perform an outlanding. While flying at approximately 300 meters, the pilot initially selected a mown field near a road crossing. During the approach, the pilot realized the approach was far too long and attempted to use airbrakes and a sideslip to reduce altitude. In a final attempt to correct the approach, the pilot executed a 90-degree turn to target a different suitable field. During this maneuver, the aircraft struck a small tree, causing it to crash.
The investigation
The investigation, conducted in collaboration with Thurgau cantonal police, examined the aircraft's condition, the pilot's experience, and the meteorological environment. Investigators reviewed the aircraft's maintenance records and found the Ka 6 CR to be in an airworthy condition with no mechanical failures identified. The investigation also analyzed the pilot's flight logs, noting that while his total flight time was relatively low for a competition pilot, his training and experience on this specific model were sufficient.
Findings
- The pilot made the decision to perform the outlanding at an altitude of approximately 300 meters, which left insufficient time to properly survey the landing area and plan the approach.
- The pilot misjudged the altitude during the final stages of the flight.
- A last-minute decision to change the intended landing field forced a sudden maneuver that resulted in the collision with a tree.
- The use of the QFE pressure setting on the altimeter may have contributed to errors in altitude perception, as the landing site was significantly lower than the departure airfield.
- The pilot's focus on maintaining the competition distance likely delayed the decision to land, leaving a very narrow margin for error.