What happened
On August 28, 2000, an AS 350 B2 helicopter, registration HB-XXL, was performing a transport flight near the Diavolezza mountain station. The mission involved transporting personnel and equipment to support a film production crew on a glacier. After picking up passengers and cargo, the pilot attempted to land on the Morteratsch Glacier near Piz Argient.
As the aircraft approached the landing site, the pilot maintained a hover approximately one meter above the surface. The rotor wash disturbed a layer of fresh snow that had fallen the previous night. During this hover, the aircraft began to drift to the left. Before the crew could react, the left skid sank into the soft snow, causing the helicopter to capsize violently onto its side. The impact caused the main rotor blades to strike the glacier, leading to significant structural damage to the rotor mast and the cabin.
The investigation
Investigators examined the wreckage and the flight conditions at the time of the accident. The investigation confirmed that the aircraft was well-maintained and that the pilot had performed diligent pre-flight preparations, including checking weather conditions with a local mountain hut warden. The aircraft's weight and balance were within legal limits, and the engine was found to be in good working order during subsequent testing.
Medical examinations revealed that the pilot died from severe head injuries caused by the impact of the cabin structure. While the passengers survived the crash with no injuries, the investigation noted that the pilot was not wearing a protective helmet. The investigation also looked into the environmental factors, specifically the presence of a 10 cm layer of fresh, undisturbed snow on the glacier surface.
Findings
- The pilot experienced a loss of visual reference points due to the whiteout effect created by the rotor wash disturbing the fresh snow.
- The lack of prominent landmarks on the right side of the aircraft, combined with the featureless snow surface, prevented the pilot from detecting the lateral drift.
- The left skid became embedded in the soft snow, making the subsequent rollover unavoidable.
- The pilot's death was directly attributed to head trauma sustained during the impact.
Safety action
- It is recommended to evaluate whether the use of an appropriate protective helmet should be made mandatory during helicopter operations to prevent fatal head injuries in similar scenarios.