What happened
On August 16, 2014, a clear day in the Mount Aspiring National Park, an AS350-B2 helicopter was performing a routine heli-ski operation. The aircraft was transporting a group of five skiers and a guide to a ridgeline near the summit of Mount Alta. During the final approach to the landing site, the aircraft began descending more steeply than the pilot had intended.
In an attempt to correct the descent, the pilot turned the helicopter away from the ridgeline and toward the mountain. However, the aircraft struck a steep, snow-covered slope with significant force, causing it to roll 300 metres down the mountainside. The impact caused the cabin structure to break apart. Of the seven people on board, five were ejected from the aircraft during the roll. Two passengers remained secured in their seats. The crash resulted in one fatality and six moderate to serious injuries. The helicopter was destroyed in the accident.
The investigation
Investigators examined the aircraft's configuration and the environmental conditions at the time of the accident. The investigation established that the helicopter was operating at a weight approximately 30 kilograms above its maximum allowable limit, and the center of gravity was positioned 3.0 centimetres ahead of the forward limit.
At the specific altitude and temperature of the landing site, the aircraft was operating at or near the absolute edge of its performance capabilities for maintaining a hover outside of ground effect. While investigators could not definitively determine if the aircraft entered a vortex ring state, they found no mechanical failures; the engine was producing high power and the aircraft remained controllable. The pilot was noted to be experienced in mountain and heli-ski operations.
Findings
- The aircraft was operating beyond its maximum permissible weight and weight-and-balance limits.
- The helicopter was flying at the very limit of its performance capability for the given environmental conditions.
- The pilot's attempt to avoid the terrain was unsuccessful due to the aircraft's marginal performance state.
Safety action
Following the inquiry, the Commission issued three recommendations to the Director of Civil Aviation. These addressed the need for operators to implement procedures requiring pilots to routinely calculate performance capabilities for intended flights and to mitigate the risks associated with using standard passenger weights that might lead to exceeding aircraft limits.