Avalanche airbags have literally exploded into the backcountry marketplace. There are at least a dozen or more manufacturers of airbags now, some offering ambitious claims of their product’s life-saving effectiveness. They have become standard equipment for backcountry guides as well as competitors on the Freeride World Tour. Some ski patrols have begun providing airbags for patrollers who work in avalanche terrain. There also been some fairly high profile skiers caught in avalanches who have credited their survival to deployment their airbag. see http://adventureblog.nationalgeographic.com/2012/03/07/survivng-the-slide-skier-elyse-saugstads-tips-on-avalanche-safety/
Take a look at this video:
Despite the growing hype around airbags, the primary question remains: Do avalanche airbags save lives?
According to several studies of data collected in Europe and Canada on avalanche accidents involving airbag use, the short answers is: Yes, airbags do seem to save lives. However, they are by no means a silver bullet and by no means a replacement for sound decision making and terrain selection.
Before going into the studies, its probably important to understand how airbags work. Statistically, most avalanche deaths are caused by asphyxiation due to burial (trauma is the next leading cause). The theory with airbags is that if you can stay on top of the snow, the risk of asphyxiation is eliminated or reduced and your chance of rescue in even a partial burial is greatly increased.
The principle behind why airbags work is called inverse segregation. This theory is also known as “the Brazil nut effect.” Basically, an avalanche is a flow of small particles. When caught in an avalanche, you become one of the particles. The inflated airbag increases your volume and decreases your density thereby allowing you to essentially become a “Brazil nut” in the flow of snow where you hopefully float to the surface. The photo below demonstrates the principle by varying density and volume. The top example shows large plastic beads floating above smaller glass beads. The lower example shows large heavier bronze beads sinking below smaller and lighter glass beads.
Here’s an example of the same principle:
Not surprising, there has been some controversy in how to interpret the data involving airbag effectiveness. Despite the controversy, one takeaway that prevails is that all of the data analysis show at least some improvement in survival of those caught in an avalanche who deploy an airbag over those who do not.
A Canadian study completed in 2012 concluded that airbags improved survival rates by 27%. This study was done from a workplace safety perspective to evaluate whether airbags should provided to those who work in avalanche prone terrain. The study found that while only 56% of victims without an airbag survived serious avalanches, 83% with airbags survived. Essentially, the study concluded that airbags would save about half of the victims caught in avalanches who would have otherwise died. http://www.avalancheresearch.ca/wp-content/uploads/2012/02/2012_Haegeli_CndAvBalloonPart1.pdf
Similarly, a 2007 study from Europe evaluated the effectiveness of airbags by examining avalanche incident reports in Switzerland and Austria. This study used a larger data set than the Canadian study, but also probably had a wider range of variables to contend with. This study concluded that airbag use reduced the mortality rate by 16%.
Subsequent reviews of the data examined in the 2007 European study have called into question some of the study’s conclusions, but nevertheless concluded that airbags still save lives. http://beaconreviews.com/transceivers/pdfs/TAR-2014-09-Vol33-No1-Airbags.pdf
Putting all this into context, the data indicates that airbags do improve your chances of survival in an avalanche.
There are some important factors to keep in mind:
- Terrain is still one of the greatest limitations on the effectiveness of airbags. They will do little to protect you from trauma such as being carried into a tree or off a cliff. They will also not do much to protect you from catastrophic burial in a deep terrain trap.
- Airbags must be deployed to work. There are a number of incidents where the user was not able to deploy his or her airbag and therefore it was not able to provide any lifesaving assistance.
- Finally, risk compensation is a real factor to consider. The benefits of an airbag will be nullified if you use one to justify traveling into more dangerous terrain. In short, the airbag is no exchange for sound backcountry decision making.
Any advantage in safety, even a modest one, is well worth it. This is particularly true if it means saving a life. If you plan to spend time in backcountry terrain this year, consider adding an airbag to your snow safety kit (beacon, probe, shovel, education/training). Pray for snow and stay safe out there this season!