What happened
On November 21, 1983, at approximately 10:55 local time, a fatal incident occurred two kilometers north of Sion Airport in the commune of Savièse. The operation involved an SA 315B Lama helicopter, registration HB-XEO, operated by Air-Glaciers SA for commercial aerial work. The pilot was conducting under-slung transport of gravel bins.
The accident took place during the twentieth rotation of the day. A client of the operation, a man born in 1925, had returned to the loading area after briefly leaving to discuss deposition locations with flight staff. He positioned himself on a narrow ledge at the edge of a retaining wall, directly beneath the hovering helicopter. As the pilot prepared to lift another bin, the man fell approximately three meters into the vineyard below and sustained fatal injuries.
Prior to the flights, a briefing was held involving the pilot, ground crew, and the victim. However, this meeting did not address the physiological effects of rotor downwash, such as dust and wind pressure. The pilot reported that all previous rotations followed a consistent pattern: lifting bins two to three meters vertically, backing up ten meters, and pivoting left. No bin swinging was observed by any witness.
The investigation
The preliminary inquiry was concluded in early 1985. Investigators established that the pilot held valid professional licenses and had logged significant flight hours. The aircraft was airworthy, and weather conditions were clear with visibility exceeding ten kilometers and no wind.
An autopsy confirmed that death resulted from traumatic lesions caused by the fall. There was no evidence of cardiac issues, embolism, or alcohol influence. Witnesses noted that the victim appeared to lose his balance suddenly. While it could not be definitively ruled out that he was struck by a bin, the investigation found no concrete evidence of such contact.
Findings
The primary contributing factors were identified as the unfavorable location of the victim and the rotor downwash which stirred up dust and gravel. The victim stood on an exiguous spot with his back to the drop-off, likely blinded or disoriented by the debris cloud generated by the rotors. The lack of safety briefing regarding rotor effects was noted as a regrettable omission.
Safety action
The report highlights the necessity of informing all personnel on the ground about the physical effects of helicopter downwash during hovering operations.