An interesting and no-nonsense discussion of how much airbags really help

Thanks Susie, worth the read!

Thanks for posting Susie!

As this is research in progress, I asked Bruce the following question about what I perceive to be a discrepancy in his report. His answer is below. It is good to hear he is interested in continuing this research.

My question:

"...I'm confused about two apparently conflicting statements in

your article, the first:

'Less likely to survive anyway if 'caught in an avalanche that does not travel
far enough for the inverse segregation process to work (larger objects rise
to the surface).'

followed by:

'In terrain with ... smaller paths, avalanche airbags have the potential to
save significantly more than half of those who would have otherwise died.' "

His response:

"Good question.  I should re-read the blog and correct any misconceptions.  I guess in that second sentence you mentioned, I should have said "lower consequence terrain."  For instance large avalanche paths can kill you by trauma of traveling at such high speeds and bouncing off of things for a long time and distance, so they tend to be more deadly.  Smaller paths are generally more survivable.  But at the same time, the debris has to travel some distance (I'm not sure how far) before the inverse segregation process works.  This would make a good subject for a research paper.   There is a lot we don't know about the effectiveness of avalanche airbags so I just wanted to put out the blog to clear up some of the misconceptions about their effectiveness.   So I guess I can't really answer your question and I'm not sure if anyone can.

Sorry I couldn't help,

Bruce"

Interesting. 

I like his statement "So at least for me, unless I’m 99.9 percent certain that the slope won’t slide, then I don’t go to un-survivable terrain."  We should probably think much more about managing consequences (instead of concentrating on trying to assess the probability of it happening based on inadequate information and experience).  Terrain management is perhaps the best survival tool.  Not saying I live up to this :-(

And don't forget that inverse segregation isn't going to work if you are in the runout zone and get hit by a natural or remotely trigger the slope above you.

Good post Susie

"If the first rule of avalanche survival is don’t get avalanched; the second rule is don’t get buried -this is why Avalanche Airbag Systems are really the only avalanche aid to improve survival  - effectively reduces the likelihood of complete burial from 39% to 16.2% lowering mortality rate from 23% to 2.5% . Rated as ‘Rescue device of choice’ by ICAR, with Class IIa evidence - good to very good"

We are all very familiar with "lies, dammed lies and statistics" and Bruce Temper's blog nicely teases out the caveats to "lowering mortality rate from 23% to 2.5%". Still, his bottom line ["My best guess is that avalanche airbag packs will probably save a little more than half of those who would have otherwise have died in an avalanche"] sounds like very good odds to me and constantly prompts me to ask why don't I get one.

One further comment is on Risk homeostasis - there is a lot of good science out there that disproves the risk homeostasis theory, for example with Ski Helmets -

Helmets do not appear to increase risky behavior:
 Hagel B, Pless IB, Goulet C, Platt R, Robitaille Y. The effect of helmet use on injury severity and crash circumstances in skiers and snowboarders. Accid Anal Prev 2005;37:103-8.

I don't think anyone has studied this for airbags - and I guess its down to the psychological profile of the user - if you're male; under 30; and a powder dude with blond dreadlocks then you probably think you are immortal anyway, ABS or not - whereas if you are a cautious, risk adverse middle aged tourer who just wants the ABS to improve their odds of coming home, then you probably won't get sucked into the risk homeostasis thing - only you know who you are !

Then there's the weight factor to take into account. Airbackpacks are heavy, which makes you more tired, tiredness can cause an accident, a fall can cause a slide. A friend of mine fell on a steep powder slope because, she says, her airpack was too heavy for her. The slope stayed intact, she was helilifted off.