Accident
On 7 September 1969 at 1513 hours, a glider pilot attempted the first conversion training flight in a Standard Libelle HB-950 at Fricktal-Schupfart airfield. During aerotow takeoff on runway 08, the glider veered left and collided with a parked LS-1 glider HB-956. No persons were injured. HB-950 sustained light damage; HB-956 was heavily damaged.
Investigation
The pilot held a valid glider pilot license. Health impairment was not indicated. Meteorological conditions were not a factor in the accident sequence. The tow started on the left side of the runway reserved for gliders, with a lateral distance of only 3 to 4 meters from gliders parked along the runway. A helper holding the left wingtip stood on the side facing the obstacles. The takeoff began normally; after the helper released the wing, the glider rolled briefly with wings level, then the left wing dropped and touched the ground. The glider, equipped with a center-of-gravity hook, had limited directional stability at low speeds and subsequently broke left. The terrain sloping in that direction may have facilitated the veer. The pilot decided to release the tow rope but did not immediately find the release handle. After the glider rotated approximately 90° from the takeoff direction, either the pilot released or the safety coupling released automatically. The glider then ground looped, collided with the parked HB-956, and came to rest after a total rotation of about 580° around the vertical axis.
Conclusion
The commission concluded that the accident was due to the tow starting too close to the parked gliders and the pilot not releasing immediately after the left wing touched the ground.