Chamonix-Mont-Blanc english summary
The event concerns the Panoramic Mont-Blanc cable car located in the Chamonix commune on the Mont-Blanc massif.
At 15:20, on Thursday, 8 September 2016, following an unexpected stoppage of the device, oscillations of the line occurred and led to a tangling of the traction cable with the carrying cable on three parts of the line.
A cable “untangling” procedure was therefore initiated. The sudden breaking of part of the motor interrupted and prevented this procedure from being completed.
At 17:20 the cable car was still stopped with 110 passengers on the line. All options for restarting it seemed exhausted. A helicopter evacuation was therefore decided upon.
54 people were rescued by 20:50, which was nightfall time. 24 other people were rescued by 22:30, but via vertical rescue and walking along the glacier. 32 people remained in the cabins all night.
During the night, the motor was repaired. A new attempt to untangle the cables was carried out at 07:15, with success. It however caused a new incident : the derailing of an empty cabin from the carrying cable. The repatriation of the last passengers was carried out at a low speed and was completed by 08:50. They were stuck on the line since 17:30.
The initiatory fact of the prolonged immobilisation of the cable car was the trigger of a safety feature that theoretically should have made the installation safer. This safety feature was activated due to a modification in the setting of the installation carried out the day before.
The latent defaults and a weak resistance of the installation and its operation led to a progressive degradation of the situation, which the operator didn’t know how to manage without using public rescue services.
The causes of the prolonged immobilisation and its repercussions were :
- the sensitivity of the device to oscillations of the traction cable which led it to cross the carrying cable in several places and thus led to immobilisation ;
- the breaking, during an attempt to uncross the cables, of a badly crimped hose on a motor that had just been replaced and whose ability to uncross the cables had not been verified ;
- the omission of devices reducing certain risks of immobilisation, due to an incomplete safety study ;
- the overestimation, before the event, of passengers’ ability to withstand hostile environments, for a long duration, and the underestimation of the assistance they would need ;
- the lack of operational rigor to ensure a high level of safety of the installation.
BEA-TT issued five recommendations and an invitation in the following areas :
- knowledge of dynamic effects on the Panoramic Mont-Blanc ;
- the safety of cabins with regard to derailing ;
- operational rigor for the maintenance of a high level of safety ;
- the consistence of feasibility testing concerning, more generally, installations sensitive to dynamic effects ;
- the quality of cable car safety studies for integrated evacuations ;
- the vigilance of cable cars safety control services.