What happened
On December 15, 1999, an AS 355 F1 Ecureuil, registration F-GJGU, was performing passenger shuttle services between the valley and the Pic de Bure observatory. The flight was operated by SAF-Hélicoptères. After completing previous legs of the day, the pilot prepared to return passengers to Montmaur at approximately 15:00 UTC.
Shortly after takeoff from the observatory, the helicopter struck the cables of a teleferic system connecting the observatory to the valley. The impact caused the aircraft to crash on a ledge near the Combe Ratin. The wreckage was located the following morning. While one passenger managed to alert emergency services via a mobile phone, the accident resulted in 5 fatalities (the pilot and four passengers).
The investigation
The investigation focused on the deteriorating meteorological conditions and the visibility of obstacles in the area. Investigators examined the aircraft's maintenance records, which showed the airframe was within operational limits, and the pilot's flight experience. The inquiry also looked into the effectiveness of the search and rescue (SAR) operations, noting that the emergency beacon was torn away during the impact and failed to transmit. The investigation also reviewed the survival equipment on board and the procedures for passenger safety briefings.
Findings
- The primary cause of the accident was the pilot's misjudgment of the rapidly deteriorating weather conditions in the high-altitude environment, which led to the decision to fly despite increasing cloud cover.
- The pilot failed to maintain adequate clearance from the teleferic cables, which were difficult to see due to low light and fog.
- The loss of the emergency locator transmitter (ELT) due to impact prevented immediate localization of the wreckage.
- The lack of specialized survival equipment for extreme cold and the absence of passenger safety briefings regarding mountain survival contributed to the severity of the outcome.
- The use of mobile phone triangulation by emergency services was a critical factor in eventually locating the crash site.