What happened
On February 4, 2009, a Eurocopter AS 350 B3, registration LN-OAO, was performing a positioning flight from Harstad to Karasjok for Heli-Team AS. While navigating through the Rostadalen valley in Troms, the crew encountered challenging visual conditions characterized by snow-covered, featureless terrain and intermittent snow drift.
Due to the degraded visibility, the pilot performed a precautionary landing to wait for better conditions. After a short period on the ground, the pilot attempted to resume the flight using a low-altitude hover taxi. During this maneuver, the helicopter suddenly lost control and rolled over. The impact caused the main rotor blades to strike the snow-covered ground, with two blades passing through the cockpit area. The pilot sustained fatal injuries, while the passenger escaped with only minor injuries.
The investigation
The Norwegian Safety Investigation Authority (NSIA) examined the sequence of events and the environmental conditions at the crash site near Måskovatnet. Investigators analyzed the aircraft's flight path, noting that the terrain became increasingly difficult to navigate as vegetation disappeared, leaving a white, contourless landscape.
The investigation focused on the mechanics of the loss of control. It was determined that the aircraft's tail guard and the lower portion of the tail fin became wedged in the snow during the low-altitude maneuvering. The pilot did not realize the tail components had made contact with the surface until the aircraft had already begun to overturn.
Findings
- The primary cause of the accident was the tail guard and lower tail fin becoming stuck in the snow during a low-altitude hover taxi.
- The transition to a featureless, snow-covered landscape created a degraded visual environment, making it difficult to perceive altitude and terrain contours.
- The pilot was attempting to maintain visual references in an area lacking significant landscape textures or landmarks.
- The aircraft lacked a radio altimeter, which could have assisted in maintaining safe clearance from the terrain during the low-altitude maneuver.