What happened
On March 14, 2012, a Piper PA-18 "150" Super-Cub, registration HB-PMN, was participating in a mountain landing training camp on the Tsanfleuron Glacier in Switzerland. The aircraft, operated by Association Snow Fish, was conducting instructional flights with a student pilot under the supervision of an experienced instructor.
During the third approach of the day, the instructor noted via radio that a Pilatus Porter aircraft, used for logistics, was attempting to take off. Despite several radio announcements from the Porter pilot, the aircraft remained stationary on the snow. The instructor suspected the Porter's skis were stuck in the snow. Because the instructor's push-to-talk radio button was non-functional, he could not communicate directly with the Porter pilot to clarify the situation.
After landing the Piper PA-18 near the stationary Porter, the instructor decided to assist by attempting to shake the Porter's wing struts to dislodge the skis. He instructed the student to keep the engine at low RPM to prevent the Piper from sliding backward. As the instructor walked toward the Pilatus Porter, he walked directly into the path of the Porter's rotating propeller, sustaining deep lacerations to his left arm and shoulder.
The investigation
The Swiss Transportation Safety Investigation Board (SUST) examined the technical and operational circumstances of the event. The investigation focused on the instructor's workload, the functionality of the aircraft's communication equipment, and the environmental factors at the glacier. Investigators also reviewed the instructor's recent flight activity and the physical conditions of the aircraft involved.
Findings
- The instructor was managing significant responsibilities, acting as both a flight instructor and the organizer of the training camp.
- The instructor had experienced a period of sustained flight activity in the ten days preceding the accident, which may have contributed to fatigue.
- A known technical fault in the HB-PMN prevented the instructor from communicating directly with the other pilot, hindering coordination.
- The high noise level from the Pilatus Porter's engine likely masked the sound of the Piper PA-18's idling engine.
- The instructor experienced a tunnel vision effect, where his intense focus on resolving the stuck aircraft caused him to lose situational awareness of the immediate danger posed by the moving propeller.