What happened
On September 4, 1972, a pilot was conducting a private flight from Reichenbach to Saanen Aerodrome. After landing at approximately 15:25 CEST, the pilot prepared for a return flight, boarding the Minicab GY-20-1, registration HB-SAC, at 16:00.
As the aircraft began taxiing from its parking position to turn right onto the taxiway for runway 08, the pilot applied increased engine power. During this maneuver, the tail of the aircraft lifted, causing the propeller to strike the ground. The impact resulted in the aircraft coming to rest in an inverted position. The pilot sustained no injuries, though the engine suffered heavy damage. No third-party property was affected.
The investigation
The investigation examined the pilot's credentials, the aircraft's airworthiness, and the environmental conditions at the time of the incident. The pilot held a valid private pilot license with an endorsement for aircraft with flaps and possessed significant flight experience, including several hours of training on this specific aircraft type. There was no evidence of health issues affecting the pilot's performance.
The HB-SAC was a homebuilt aircraft found to be airworthy and properly registered. The mechanical brakes were functioning normally, and the aircraft's weight and center of gravity were within permissible limits. However, it was noted that for this specific taildragger configuration, the center of gravity typically remains in the forward position. At the time of the accident, a 4-knot tailwind was present.
Findings
Investigators determined that the accident was likely caused by insufficient pilot attention during taxiing. Specifically, the pilot failed to account for the fact that the aircraft was positioned with the tail facing into a tailwind while the center of gravity was forward. The combination of increased power applied during the turn and potentially excessive braking likely triggered the uncontrolled lifting of the tail.