1995 AS 350B2 Helicopter Accident in Glarus (HB-XVT)

Overview and Investigation Context On August 12, 1995, an AS 350B2 helicopter, registration HB-XVT, operated by Heli Linth AG, crashed during a takeoff from the alpine landing site Mittel Stafel in the Klöntal, Glarus, Switzerland. The Swiss Federal Accident Investigation Board (BFU) issued its final report under the accident investigation regulations, based on an earlier investigation report from June 7, 1996. The investigation was opened the same day in cooperation with the Glarus cantonal police. ## Flight Background and Crew The helicopter was based at Mollis and used for air ambulance and occasional material transport. On the day of the accident, the flight was organized by a private pilot, A, who had completed basic training with Heli Linth AG and was authorized for certain private flights. A was not an employee of the company. Professional pilot C, who was on duty with another helicopter, agreed to accompany A as a safety pilot. Pilot B, who had originally been scheduled to accompany A, was recovering from a foot operation and was only partially fit for duty. ## Accident Sequence The helicopter landed on a small, level area near the alpine hut with the main rotor running. Pilot C, seated in the front left seat, exited the aircraft and helped three passengers disembark. As cargo was being brought to the helicopter, the aircraft suddenly lifted off with a sharp pitch-up movement toward the rising terrain. The main rotor blades struck the ground, and the helicopter rolled over. The pilot sustained fatal injuries, and the helicopter was heavily damaged. ## Aircraft and Site Conditions The AS 350B2 was a single-engine, six-seat turbine helicopter with fixed skid landing gear, manufactured in 1991. The aircraft's mass and center of gravity were within limits. The landing site had a slope of approximately +3° to +5° toward the hillside and was grass-covered with small stones. The ground was softened by continuous rain. Weather conditions included light rain, visibility of 2 to 5 km, and variable winds around 2 kt. ## Findings and Cause The investigation found that the accident was due to an uncontrolled and inconsistent takeoff maneuver and incomplete and confusing information before and during the flight among the persons involved. The helicopter rotated 90° counterclockwise during the takeoff and crashed uncontrolled onto the landing site. All main rotor blades were sheared off at the rotor head, and the tail rotor was destroyed upon ground contact.