What happened
On December 22, 2003, an AS350B3 helicopter, registration HB-ZCS, was performing a commercial VFR flight near the Glacier du Sex Rouge in the Canton of Valais. The mission involved transporting maintenance personnel to repair a cable car system. After a brief stop at an intermediate station, the aircraft proceeded toward the upper station, flying alongside the cable lines.
During the descent toward the lower station of the glacier lift, the aircraft entered an area of difficult weather. The terrain consisted of a snow-covered glacier under overcast skies with intermittent light snowfall and gusty north winds. As the pilot maneuvered around a rocky ridge, the aircraft struck the terrain. The impact was severe enough to detach the tail boom and cause the main rotor head and gearbox to separate from the airframe. The collision resulted in one fatality and one serious injury, while two other passengers escaped with minor injuries.
The investigation
Investigators examined the wreckage and the flight data, including the Vehicle Engine Management Display (VEMD), which confirmed the engine was functioning normally at the time of the accident. The investigation also looked into the pilot's recent flight experience, noting a low number of flight hours in the preceding 90 days.
Technical analysis of the aircraft revealed that the weight and center of gravity were within limits and no pre-existing mechanical failures were found. However, the investigation identified that the Emergency Locator Transmitter (ELT) was non-functional due to a jammed activation switch, and there was no evidence of recent maintenance records for the device. Additionally, the aircraft was not equipped with mountain survival gear.