What happened
On 8 July 2009, an Eurocopter SA315B (Lama), registration HB-XII, was conducting a commercial rescue flight near the Dufourspitze in Zermatt. The mission was initiated to evacuate a climber who had become unwell during a descent. A rescue specialist was lowered from the hovering helicopter to the site, where a mountain guide had established a belay point using a large stone slab on a rock pillar.
During the evacuation, the rescue specialist attached the patient and several backpacks to the Multilateral Evacuation and Rescue System (MERS) for lifting. As the helicopter began to lift the load, the safety rope connecting the guide to another climber on the ground was unintentionally caught by the ascending load. The upward movement of this rope caused the guide to stand up from his crouched position to attempt to release the tension. In doing so, he lost his balance and fell backward off the pillar. During the fall, a heavy stone slab used for the belay also fell, likely striking the rope and causing it to sever. The guide fell several hundred meters down the mountainside, resulting in one fatality.
The investigation
SUST examined the flight history, the equipment used, and the physical evidence at the scene. Investigators analyzed the rope, which had been recovered after the accident. Forensic testing by the Zurich City Police and specialized mountaineering equipment experts found that while the rope showed permanent deformation and fraying at the severance point, it had passed standard dynamic drop tests and was in acceptable condition for its age.
The investigation also reviewed the radio communications between the pilot and the rescue specialist. It was noted that the communication did not strictly adhere to the operator's established Code of Practice, as the standard phraseology for confirming the line was clear was not fully utilized.
Findings
- The primary cause of the accident was the unintentional lifting of the safety rope connecting the climbing party, which triggered the guide's fall.
- The preparation of the lift site was incomplete, as the load being hoisted became entangled with the ground-based rope without the crew noticing.
- Neither the helicopter crew nor the rescue specialist observed the rope being lifted with the load.
- Radio communications between the rescue specialist and the pilot were minimal and did not meet the requirements of the operator's Code of Practice.
- The method of using a stone slab for belaying was considered a standard and acceptable practice in such terrain.
- The severance of the rope was likely caused by the stone slab striking it during its fall.