What happened
On May 16, 1971, a Jodel D 120, registration HB-SPL, was completing a private flight from Porrentruy to Triengen. As the aircraft was taxiing along the paved runway following its landing, it began to veer off course. In an attempt to prevent a collision with another aircraft that was taxiing just off the right side of the runway, the pilot applied intense braking. This sudden deceleration caused the HB-SPL to lose stability and flip over at the right edge of the runway. The incident resulted in two serious injuries for the pilot and the passenger, while the aircraft sustained heavy damage. No third-party property was harmed.
The investigation
The investigation focused on the mechanical state of the aircraft, the pilot's competency, and the airfield conditions. The pilot, who held a valid private pilot license and had approximately 71 flight hours, was found to be in good health at the time of the accident. Investigators found no evidence of technical malfunctions or mechanical failures contributing to the loss of directional control. Meteorological conditions were determined to be irrelevant to the event.
Findings
Investigators identified that the available grass area northwest of the runway was significantly restricted due to a soil depot. This restriction forced taxiing aircraft to operate very close to the runway edge, creating a heightened risk of collision if an aircraft were to veer off the pavement. Furthermore, the airfield manager failed to notify the Federal Office of Civil Aviation regarding this operational difficulty or request a NOTAM to alert pilots to the increased danger.
Safety action
The investigation highlighted a failure in communication regarding airfield hazards, specifically the lack of reporting the restricted taxiway space to the relevant aviation authorities.