Incident Summary
On 14 December 2002, at approximately 10:15 local time, an Air Zermatt SA315B Lama helicopter, registered as HB-XTY, was conducting a passenger flight near the Breithorn Glacier in Zermatt, Switzerland. During the flight, the occupants heard a sudden dull detonation followed by intense vibrations. The pilot decided to perform an immediate emergency landing on the glacier. The helicopter swerved and came to rest on its left side, sustaining substantial damage.
Flight Details
The pilot reported that while flying at an altitude of about 3700 m AMSL (approximately 400 m above ground) on a heading of 080 degrees north of the Breithorn, a loud bang occurred accompanied by violent shaking. The helicopter began to sink. The pilot reduced power, but strong low-frequency vibrations persisted. The collective and cyclic controls remained free and did not exhibit abnormal feedback. The pilot focused on selecting a crevasse-free landing area and issued a mayday call. Attempts to increase collective pitch to counter rotor overspeed were ineffective. At about 20-30 meters above ground, the pilot attempted a flare, but the collective pitch control did not respond, resulting in a near free-fall impact into deep snow. The helicopter tipped onto its left side due to the sloping terrain.
Injuries and Damage
The helicopter was heavily damaged. The pilot and two passengers sustained minor or no injuries. The other two passengers' injury status was not specified in the report. There were no fatalities or serious injuries recorded.
Investigation and Cause
The investigation was conducted by the Swiss Aircraft Accident Investigation Bureau (Bureau d'enquête sur les accidents d'aviation). The probable cause was determined to be a collision with terrain after loss of control following a technical failure that rendered the helicopter only partially controllable.