What happened
On June 26, 196 and, a training flight took place at the La Chaux-de-Fonds airfield. A student pilot was operating a Karpf Baby glider, registration HB-513, which was being towed by a Piper PA-18 aircraft. During the takeoff from runway 06, the aircraft encountered significant crosswinds and moderate to heavy turbulence.
Shortly after a normal takeoff, the glider drifted slightly off the runway centerline. At an altitude of only 10 to 15 meters, the pilot released the tow cable. Following the release, the glider banked heavily to the right and began a low-altitude turn. The aircraft's right wing struck the roof of a hangar located near a farm, and the fuselage subsequently hit the ridge of a farmhouse roof before the glider fell vertically to the ground. The pilot sustained grievous injuries and the glider was destroyed.
The investigation
Investigators examined the wreckage of the Karpf Baby and performed a functional check of the flight controls. The investigation confirmed that the control linkages were correctly installed and no cables were defective. The aircraft's center of gravity had been within prescribed limits at the time of the accident.
Regarding the pilot's experience, the student had significant time in powered aircraft but very limited experience in gliders, with only 3 hours and 10 flights recorded, only a small fraction of which were solo. The instructor involved was highly experienced in glider operations.
Findings
- The primary cause of the accident was likely a reaction of panic by the student pilot.
- The pilot's decision to release the tow cable at a very low altitude was triggered by the glider drifting from the runway axis.
- While the pilot attempted to correct the rightward bank using ailerons and rudder, the force of the wind exceeded the effectiveness of the corrections.
- The investigation suggests the pilot may have experienced a momentary panic, leading to a physical tension on the controls or an instinctive decision to disconnect the cable to avoid further deviation.