What happened
On June 5, 2010, an SA 315B Lama, registration HB-XND, was performing a commercial VFR mission near the Neue Monte Rosa Hut in Zermatt. The flight plan had been modified shortly before departure, requiring the pilot to transport a 680 kg underslung load and subsequently pick up passengers.
During the operation, the pilot arrived at the site to deposit the load. Rather than using the established landing area located approximately 30 meters from the building, the pilot attempted to land on the hut's terrace to facilitate the passenger pickup. The terrace was not prepared for such an operation, as it contained obstacles such as bins and poles, and parts of the surface were still covered in snow.
As the helicopter descended toward the terrace, the main rotor struck the wall of the building at a height of approximately 3.62 meters. The impact caused the aircraft to tilt sharply to the left and crash onto its side. The pilot sustained significant injuries but was rescued from the cabin by the hut warden and bystanders. The aircraft was destroyed, and the impact caused damage to the building's solar collectors and windows.
The investigation
SUST examined the flight logs, weather data, and the physical wreckage. The investigation established that the pilot was flying without a dedicated flight assistant, despite having requested one. Instead, the pilot relied on the hut warden for guidance. The investigation also reviewed the architectural features of the hut, noting that the wall's asymmetric, widening shape and potential light reflections could have made distance estimation difficult for the pilot.
Findings
- The primary cause of the accident was the collision of the main rotor with the building during a landing on an unsuitable landing site.
- The landing area was not cleared of obstacles and was too confined for a safe maneuver.
- The pilot relied on instructions from the hut warden, who was neither trained nor equipped as a professional flight assistant.
- The decision to land on the terrace instead of the nearby established landing pad introduced unnecessary risk.
- The combination of transporting an underslung load and passengers was being performed, a practice that had previously been subject to regulatory scrutiny.