During an avalanche snow and debris starts to fall down the slope, the larger particles come to the surface and the smaller particles work their way towards the bottom of the debris. This is much like the way a packet of crisps work, larger crisps are always at the top of the packet and the smaller broken pieces find the spaces and are always at the bottom. Or the way you always have broken biscuits in the bottom of a biscuit jar and the whole biscuits at the top.
With this in mind, the larger you are the more chances you have of staying nearer the surface of the snow and therefore the more chances of survival. If you think an avalanche has started you can activate your bag. A large balloon like bag inflates out of the top of your backpack; with the airbag activated you are much bigger than you would usually be, helping you stay nearer the snows surface. Avalanche airbag balloons are always hi-visibility colours so you can easily be seen from a distance.
An avalanche airbag is a ski backpack with an integrated balloon airbag system fitted inside. A pull cord fitted within the backpack shoulder strap, working much like a parachute pull cord, triggers the balloon to inflate. When the cord is pulled an air canister is triggered, inflating the balloon with a tiny air turbine within a few seconds.
Airbag backpack inflation systems vary considerably. Some use a mechanical trigger to activate an air canister and others use a tiny internal explosive charge to trigger a gas canister. Newer rechargeable battery operated versions are also now available. There can be pros and cons to all these styles of activation units – air canisters can sometimes be tricky for airplane travel, whilst battery operated ones should cause you no problems. Battery units also allow you to practice setting off the airbag as it can be set off multiple times on one charge.
If you get knocked over by an the avalanche you will tumble and feel very much like you’re in a giant washing machine. The snow drags with it rocks, large chunks of ice, trees and anything else in its way. With this in mind the airbag balloon inflates around your head and is designed to help protect you from the effects of tumbling and from debris hitting you. Some airbags are cleverly designed to keep injecting air into the balloons every few seconds, this means if the balloon gets punctured it will still stay inflated.
In the unfortunate event of you getting buried under the snow the bag will begin to slowly deflate leaving you with a breathing air pocket under the snow.
Avalanche airbags are not a replacement for avalanche transceivers, which are a must when skiing off piste. They are also not a license to ski in unsafe terrain, but an aid to helping you if you are in the unfortunate situation of being caught in an avalanche. Be prepared, but make sure you are always very aware of the current avalanche conditions wherever you are skiing.