 Poster: A snowHead
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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Not at all already posted just below. 
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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Oops sorry didn't see your post 
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You need to Login to know who's really who.
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skimottaret, well thanks anyway
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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. They will never save all of them because 1 out of 4 will likely die from trauma of hitting trees and rocks on the way down and an additional 1 out of 4 will probably end up in a terrain trap (deep burial), buried by a secondary avalanche or caught in an avalanche that does not travel far enough for the inverse segregation process to work (larger objects rise to the surface).
In addition, people will increase their exposure to risk because of the perception of increased safety, which will cancel out some, but not all, of the effectiveness of avalanche airbags.
As usual, our choice of terrain is far more important than rescue gear. Un-survivable terrain will always be un-survivable. In terrain with few obstacles, terrain traps, sharp transitions and smaller paths, avalanche airbags have the potential to save significantly more than half of those who would have otherwise died. And that sounds pretty good to me. |
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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| meh wrote: |
| Not at all already posted just below. |
hat tip to meh for his post also.
This had me all interested (I love a statistical b/s argument cf the BMJ "walking helmet" study...) until I got to the "Just Got Lucky" component of the group. Hmmm. Difficult to completely follow logical reasoning after that bit...
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You'll need to Register first of course.
You'll need to Register first of course.
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| Quote: |
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. They will never save all of them because 1 out of 4 will likely die from trauma of hitting trees and rocks on the way down and an additional 1 out of 4 will probably end up in a terrain trap (deep burial), buried by a secondary avalanche or caught in an avalanche that does not travel far enough for the inverse segregation process to work (larger objects rise to the surface).
In addition, people will increase their exposure to risk because of the perception of increased safety, which will cancel out some, but not all, of the effectiveness of avalanche airbags.
As usual, our choice of terrain is far more important than rescue gear. Un-survivable terrain will always be un-survivable. In terrain with few obstacles, terrain traps, sharp transitions and smaller paths, avalanche airbags have the potential to save significantly more than half of those who would have otherwise died. And that sounds pretty good to me. |
Very nice piece, well worth a read. Thanks for pointing it out.
A couple of comments ...
The 1/4 death by trauma is a US figure; in Europe that figure is a lot lower. I don't have any stats to hand, but it's less than 10%. This is thought to be due to differences in terrain, primarly the fact that we have much less gladed tree skiing which is where a lot of trauma occurs in US accidents.
I have not seen terrain trap stats - a lot of terrain trap deaths are also trauma deaths - a terrain trap is anything that makes to consequences of an avalanche more serious, so hitting a rock or a tree is both terrain trap and trauma - I hope those stats are not "double counting" those numbers (edit - just realised who the author is, I doubt he was double counting anything, he *really* knows his stuff). However, for terrain traps such as steep transitions, gullies and narrow valleys this is indeed somewhere where an ABS will not help much.
His comments about risk homeostasis (people take more risks because they have better gear) is a common one and hard to discount. However, there are ways to make decisions that attempt to minimize this effect in your own mind (you need a little bit of training or background reading, but's its no rocket science). Some studies on helmet use by skiers show very little risk compensation actually goes on; this doesn't mean the same applies to airbags though.
The author is spot on when he calls out the way stats are used here, when you see stats like "97%" effective you have to be very skeptical.
The final point is key!
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Are there ANY downsides to wearing an avalanche airbag? I'd be interested to hear...
With helmets - there are conditions in which they impact negatively on safety:
- a helmet increases the weight of the skull and thus contributes to an increased torque on the neck
- a helmet can snag on posts, tree branches or netting
- helmets with ear cover can obscure hearing
- some helmets can impair peripheral vision -
These are minor downsides (BUT they ARE downsides) when compared to the head protection they offer: I always wear a helmet save when skinning but it is on my pack then.
Side point:
Baffles me why so many Guides don't wear helmets. A French helmet-wearing guide observed to me that only 2% of his colleagues wore helmets (God knows where he plucked that figure from) but it is very safe to say that most guides don't wear helmets. If I was a guide I'd wear a helmet if only to protect me from an enthusiastic client dropping in on me. sorry - slightly off-topic
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Grinning, cost, weight, issues with airlines and availability are possible reasons people don't buy them.
Cost is something you have to balance against other demands in your cash, weight is not really an issue for lift served skiing, airlines are getting better and the rules are very clear, you are allowed to fly with them. Availability is the biggest blocker... the one I want is proving hard to find in the UK and st. Anton, so I'll wait until next season. There are a few models in the shops though, but I'm told that the cylinders are hard to source for the ABS system even if you find a pack.
I think the main issue is that Americans have cottoned on and so demand has gone through the roof.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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interesting article, but could anyone explain what a "sharp transition" is? Is it a euphemism for a cliff?
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| DCG wrote: |
| interesting article, but could anyone explain what a "sharp transition" is? Is it a euphemism for a cliff? |
Its where a steep slope flattens out abruptly (e.g. when a piste or cat track crosses a slope). Avalanche debris can build up and burials can be deeper than would have been the case otherwise.
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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sah, Thanks for that.
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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There is a massive problem with interpreting all of the avalanche airbag data- i.e. all of the studies are retrospective case control studies, which are notoriously prone to selection bias. In the case of avalanche accidents, it's much more likely that serious or fatal accidents are reported (as indeed is the case in the study that Tremper alludes to in his article). Thus, if airbags are more likely to make accidents less serious, then their effectiveness will be underestimated by such a study, as the successful outcome won't be reported. On the other hand, if people in avalanche accidents who deploy an airbag and are unharmed are more likely to report the incident, then this will over-estimate their effectiveness. It is practically impossible to control for this type of bias completely. Tremper describes the study that he mentions as treating airbags like a medical intervention. This is a good start, but the point is that you would NEVER assess the efficacy of a medicine in this way- you would do a prospective, randomised trial (perferably double blind, but that would involve giving the control group rucksacks with empty cylinders, which doesn't seem very ethical). As avalanche deaths are rare, it would need to be big and consequently expensive, and who's going to fund that? Not government medical research bodies I should think- avalanche deaths are a tiny fraction of all cause mortality.
My interpretation of the data is that it's pretty clear that avalanche airbags reduce your chances of dying in an avalanche, but that we don't have the necessary information to quantify this effect with any certainty. They are probably more effective in Europe than N. America (I write this from Tahoe at the moment, and I can tell you there's way more in the way of trees to hit on the way down!).
Disclaimer: I sell the things.
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| sah wrote: |
| Grinning, cost, weight, issues with airlines and availability are possible reasons people don't buy them. . |
All factors of convenience and budget but not of safety. Any takers for a safety disadvantage of wearing a bag?
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You know it makes sense.
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| Grinning wrote: |
| sah wrote: |
| Grinning, cost, weight, issues with airlines and availability are possible reasons people don't buy them. . |
All factors of convenience and budget but not of safety. Any takers for a safety disadvantage of wearing a bag? |
The only one that I have heard is; that they may change your risk perception and you end up taking undue risks that you would not have if you weren't wearing the bag.
Personally I don't think my risk perception changes, but that is just me.
Despite having a 'sensation seeking personality' I am a big fan of safety kit and therefore I like my snowpulse airbag!
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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Grinning, one thought is that by staying on the surface you increase your risk of traveling further so in treed terrain you have an increased chance of sustaining trauma. No data to support that though, like the supposed helmet risks.
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Poster: A snowHead
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Grinning, the avalung is a better piece of kit if you are skiing somewhere where falling in tree wells is a concern
anyway, i am wary of this turning into a helmet-type discussion where a perceived increase in safety is seen as trumping any other consideration
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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| Grinning wrote: |
| sah wrote: |
| Grinning, cost, weight, issues with airlines and availability are possible reasons people don't buy them. . |
All factors of convenience and budget but not of safety. Any takers for a safety disadvantage of wearing a bag? |
Pulling the trigger on a chairlift? Risk homeostasis (as mentioned above); other than that, no, I don't know of any.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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| Arno wrote: |
| anyway, i am wary of this turning into a helmet-type discussion where a perceived increase in safety is seen as trumping any other consideration |
Any takers for a safety disadvantage of wearing a bag?
There you go, it just did precisely that.
I can't see any safety reason that you should not wear an airbag in bed, along of course with your Avalung, helmet, radio, wrist guards, impact shorts, and body armour. You'd be safer sleeping in a concrete bunker, so I trust you're all out there digging one right now. You know it makes sense,
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You need to Login to know who's really who.
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sah, Which model are you after? I have a powder 15 with carbon cylinder and its brilliant and highly recommended for lift accessed freeride, I just wear it all day long and it's just same as a normal rucksack. Airports are now 100% sussed with them, normal kit at security, we just put trigger and canister in the hold.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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Markymark29, One of the Mammut / Snowpulse ones, probably the ~22L one. I want to have a look at the different models side by side. Actually, they are based on normal Mammut packs so I may have a wander around town later on and have a look at those to get an idea of the size. It's going to be a day sack, but I'd like to be able to take touring gear for the rare occasions when I do that 
I sat next to German couple who had a Mammut and an ABS so they were able to compare the 2; both highly rated but on balance they reckoned the Mammut was better, although the ABS zip on system was more flexible.
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You'll need to Register first of course.
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sah, when I chose mine, I just went with the best pack for me. i concluded that the differences in the technologies was pretty minimal
that said, way back then (2 seasons ago!) it was basically a choice between ABS and Snowpulse
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| sah wrote: |
| Grinning wrote: |
| sah wrote: |
| Grinning, cost, weight, issues with airlines and availability are possible reasons people don't buy them. . |
All factors of convenience and budget but not of safety. Any takers for a safety disadvantage of wearing a bag? |
Pulling the trigger on a chairlift? Risk homeostasis (as mentioned above); other than that, no, I don't know of any. |
wear your bag (skiing), usually wear a helmet and don't pull the trigger on a chair: simples
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FAQ
