What happened
On July 22, 1965, a Jodel D-11, registration HB-SUY, was involved in a ground incident at the Wangen-Lachen airfield in the Canton of Schwyz. The pilot was preparing the aircraft for departure and was performing solo ground operations. While the engine was running, the pilot removed the wheel chocks. Immediately following the removal of the chocks, the aircraft began to move unexpectedly, eventually sliding into a nearby ditch. The incident resulted in damage to the airframe.
The investigation
An investigation was conducted by the Swiss Federal Aircraft Accident Investigation Commission. The inquiry focused on the sequence of events during the pre-flight phase, specifically examining the aircraft's movement following the removal of the wheel chocks while the engine was operational. The investigation concluded that the aircraft's motion was triggered by the removal of the chocks during engine run-up/startup procedures.