Accident Details
On 24 January 2014, at approximately 11:15 local time, a Eurocopter SA315B Lama helicopter, registration HB-ZHZ, operated by Air Glaciers SA, was involved in an accident at Höhenlücke, near Lauterbrunnen in the Bernese Oberland, Switzerland. The helicopter was performing a commercial flight under visual flight rules (VFR) with a pilot and a flight assistant on board. The accident occurred during the disembarkation of the flight assistant while the helicopter was in a hover. The flight assistant sustained serious back injuries, and the helicopter was undamaged.
Sequence of Events
The day's schedule included transport flights and avalanche blasting in the Mürren-Schilthorn ski area. After completing two assignments, the crew returned to the heliport at Lauterbrunnen. At about 11:00, they started the third assignment. The helicopter carried a 30-meter-long transport cable with a sling. At Winteregg station, the flight assistant attached a mobile toilet unit to the cable sling. The crew then flew to Höhenlücke, where the pilot deposited the toilet unit. The pilot then hovered nearby and detached the transport cable from the helicopter's cargo hook. As no ground personnel were present, the pilot intended to set the flight assistant down from the hover so he could collect equipment for the return flight.
Using a red sign protruding about 6 meters from the snow as a visual reference, the pilot hovered approximately 3 meters from the sign and slowly descended. Snow was stirred up by the rotor downwash. The flight assistant opened the left door and monitored the helicopter's tail rotor and left side. He informed the pilot of a piste marker and requested a slight right correction, which the pilot executed. The flight assistant then stepped onto the left skid, closed the door from outside, and estimated the height above ground to be about half a meter before stepping off. He fell onto the hard snow at the edge of the piste, seriously injuring his back. The pilot requested medical assistance, and a rescue helicopter transported the flight assistant to a hospital.
Meteorological Conditions
At the accident site, at an elevation of approximately 1900 m AMSL, the weather was influenced by a col between high-pressure systems. Approximately 10 to 15 cm of light, powdery snow had fallen during the night. The sky was 5/8 to 7/8 cloudy with variable cloud base between 2000 and 2200 m. Visibility below 1800 m was about 8 km, but variable above that altitude. The wind was from 360° at 3 knots. Temperature was -9 °C, dew point -8 °C. The conditions included rapidly changing visibility and diffuse light.
Cause
The accident was caused by the flight assistant misjudging the height during disembarkation from a hovering helicopter in diffuse visibility conditions, leading to a fall. The absence of ski goggles may have contributed to the incident.