What happened
On August 3, 1977, at approximately 16:48 local time, a Ka 6 CR glider, registration OE-0558, departed from Samedan Airport for a soaring flight in the Alps using a winch launch. Shortly after the release of the winch cable at an altitude of roughly 400 to 500 meters, the aircraft's air brakes were deployed. The glider proceeded to fly toward the Muottas Muragl slope and then turned back toward the departure point.
During the return, the aircraft experienced a significant loss of altitude due to the extended brakes. As the pilot attempted a tight left-hand turn to initiate the landing approach at 16:55, the aircraft entered a stall at a very low altitude. The glider struck the right bank of the Inn River at a steep angle, resulting in the death of the pilot and the total destruction of the aircraft.
The investigation
Investigators examined the wreckage and the flight sequence to determine why the air brakes were deployed. Witnesses observed the brakes moving in and out immediately after the cable release, suggesting they were not properly locked. The investigation considered the possibility that the pilot may have accidentally triggered the brake lever while attempting to verify the release of the winch cable, a common procedural step.
Technical analysis of the wreckage confirmed that the control cables, linkages, and brake mechanisms were properly connected and secured. There were no evidence of pre-existing mechanical failures or improper weight and balance; the aircraft's center of gravity was within limits. The investigation also noted that the pilot had not flown this specific model since 1969, which may have impacted his familiarity with the cockpit controls.
Findings
- The primary cause of the accident was the underspeeding of the aircraft below its minimum flying speed during the landing turn.
- The deployment of the air brakes following the winch release and the pilot's failure to retract them contributed to the loss of altitude.
- An inadequate landing pattern and poor energy management during the approach prevented the pilot from maintaining sufficient altitude for a safe landing.