Accident Overview
On 5 September 1987, a SA 315 B helicopter, registered HB-XPP, operated by BOHAG, was involved in an accident at the Eiger north face, approximately 6 km south of Grindelwald, Switzerland. The helicopter was conducting commercial transport of equipment, a mountain guide, and a cameraman to a pillar on the mountain face.
Flight Sequence
The pilot planned multiple flights due to weight and space constraints. During the second flight to the filming location, the helicopter was in a hover near the rock face. As the first of two passengers prepared to exit, with one foot still on the skid, the pilot felt a shock on the collective lever and heard a cracking sound. The pilot waited until the passenger was fully clear before initiating an emergency landing to the nearest suitable location.
Damage and Conditions
Examination after the landing revealed damage to the tips of all three main rotor blades. The leading edge of one blade exhibited damage consistent with a rock strike. Weather conditions at the time included 3 to 8 oktas cloud cover with a variable base up to 3000 m, visibility more than 10 km, wind variable around 3 knots, and temperature 9°C. The pilot held a valid commercial helicopter license and was authorized to perform the flight.
Probable Cause
The accident was attributed to contact of the main rotor with rocks following a rockfall during a hover.