Standard Libelle collision during aerotow launch at Fricktal Schupfart airfield
On September 7, 1969, a Glasflügel Standard Libelle was involved in a collision during an aerotow launch at Fricktal Schupfart Airfield in Switzerland. The incident occurred when the aircraft veered left and struck a parked glider, resulting in minor damage to the Standard Libelle and severe damage to the other glider. No injuries were reported. The investigation concluded that the tow started too close to parked gliders, and the pilot delayed releasing the tow rope after the left wing touched the ground.
- Aerotow takeoff roll: During an aerotow departure from runway 08, the glider HB-950 began its takeoff roll on the left side of the glider strip with parked sailplanes only 3–4 meters away.
- Tow too close: The aerotow was initiated with the towplane–glider combination starting excessively close laterally to a line of parked gliders along the runway.
- Left wing strikes ground: Shortly after the wing runner released the left wing, the glider rolled briefly wings level, then the left wing dropped and contacted the ground.
- Glider yaws left: With the wingtip on the ground and limited directional stability due to the CG tow hook and sloping terrain, the glider veered sharply left out of the takeoff path.
- Delayed tow release: The pilot attempted to release the tow rope but could not immediately locate the release handle, so the glider continued to pivot until the rope was finally released or the safety coupling let go after about a 90° turn.
- Ground loop develops: After tow release, the glider continued rotating on the ground, performing a ground loop of roughly 580° about its vertical axis.
- Crash - no injury: During the ground loop the glider collided with the parked LS-1 HB-956, causing light damage to HB-950 and severe damage to HB-956, with no injuries to persons.