What happened
On the afternoon of June 6, 1995, a Robinson R44 (implied by context of scenic flight/NZ operations, though source only provides registration ZK-HDI) was performing a scenic flight when the pilot attempted a landing on a snow-covered surface. During the initial touchdown, the right skid of the aircraft began to sink into the snow. In an effort to stabilize the aircraft, the pilot lifted off and moved the helicopter approximately 10 to 15 meters to a location that appeared more level.
However, as the pilot attempted a second landing in the new position, the aircraft tilted toward the right once more. In the process of attempting to correct this tilt and regain control, the helicopter underwent a rapid roll onto its right side.
The investigation
The investigation focused on the mechanics of the landing and the environmental conditions present at the time of the accident. Investigators examined the interaction between the helicopter's skids and the snow surface, specifically looking at how the shifting weight and terrain contributed to the loss of control. The inquiry also looked into the pilot's decision-making process during the two landing attempts and the difficulty of evaluating the stability of the snow surface from the air.
Findings
The investigation established that the accident was driven by two primary factors: the inherent difficulty in accurately judging the stability and depth of snow conditions from the cockpit, and the occurrence of a dynamic rollover. The inability to perceive the true nature of the snow surface led to the initial skid drop, which set the stage for the subsequent uncontrolled roll during the second attempt.