Just recently I got into a discussion about ABS backpacks. For those few who do not know what this was: Basically you carry an airbag in your pack that is being filled with air after pulling the trigger. The air comes from a capsule and inflates the airbag to a volume in the 170l region. Why? The principle behind this is described in Wikipedia. In a heterogeneous mass the smaller things sink to the ground while bigger things afloat.
Avalanche airbags build up on this principle by giving a skier a higher volume and thereby allowing to come to rest at the top of the avalanche. And this already is the crux: “At the top” still left the skier buried. Airbags cannot guarantee that you are not buried in the avalanche! As shown by Meier and Harvey (2010) the depth has been decreased by wearing an airbag, but a dummy is still being buried.
Most articles claim that an airbag was not sufficient to leave shovel and probe behind. I cannot see any necessity to underline this, because they are mandatory equipment in the backcountry during winter times regardless of any complementary stuff you bring. You would not drive your car without seatbelt just because you have an airbag, would you?
This exactly leads to the next problem I have with airbags. A decrease in risk might be felt and people start reacting to this by adding to their willingness to ski more dangerous slopes. How comes? Basically there is a certain risk aversion in everybody. Some people tend to minimize risk in every part of their life; others embrace it and become some kind of adrenaline junkie (because this is what your body does in order to allow you getting out of a situation: flooding your system with adrenaline).
By taking an airbag you give yourself some sort of comfort that in case of an avalanche your chances would be better. Well, think again.
First of all, you have to identify the avalanche as that what it is. From my experience it takes some time to realize what you just started, looking down at you ski and seeing the snow underneath starting to break into smaller chunks. It is hard to believe that you ended up in an avalanche when you were not expecting it (different scenario would be riding into a 45 degree slope with 40cm of fresh snow on an icy underground).
Then you start considering when to pull the trigger. Immediately or rather wait a little and see how it goes? As everything in life that is important, you should be training the pattern of reaching to the trigger and pulling it. The shock start almost immediately after learning that you are in an avalanche, therefore you hardly have time (same feeling I had when crashing the catamaran of my uncle – not good).
I have not pulled the trigger at all, because the avalanche was really small in size and I stopped just a few seconds after it started. Not buried because I only fell in the last second and was able to ski on the top. One leg nevertheless was in the snow.
This is the next aspect that people tend to miss. A failure of the system: When courses do avalanche trainings, this happens in not-avalanche-snow. You could not be more off from what the snow conditions are really like. Think cobblestones of 40cm, they just look white. Avalanche snow is exactly that, pressed like concrete. There was no way for me to move my leg. This would mean that when you are buried, you couldn’t rescue yourself. Forget about it.
Your buddies have less snow to shovel, fair enough, this might give you a few minutes (if you are still alive, because the trauma suffered while being mangled in the avalanche can easily cause lethal injuries).
On Ski theory you can find an well-written article on avalanches and the aftermath. There is a lot of work to be done after somebody was found and he is not at all safe just because he or she was found. I do not want to cover this in detail again, just refer to Ski theory for more info
Overall, what I want to say is that there is only one way of getting along with avalanches: Not starting them in the first place. There are certain scenarios that simply have to go wrong. Do your homework: read the snow report every day to know that the snowpack is like. Test „rutschblocks“ to learn more about the different layers in the snow. Learn about avalanches by reading all the books around, develop a risk management that works with your group and by all means: Just stay home when the conditions are bad.
a final remark:
Kindly note that all of the above written is covering avalanches caused by skiers. This does not refer to those caused by falling seracs or those getting off without third party influences. I understand that these avalanches occur and that there is hardly any way of preparing for it or escaping them. They are what I consider objective dangers beyond control (you can try avoiding routes under seracs, but sometimes you have to go a certain way with no other possibility). Do not get me wrong, I am not saying that there was something people could have done to avoid this tragic accidents. On the other hand there are things skiers can do to avoid starting an avalanche and I wanted to underline that again. For details refer to the literature on this topic. They can teach this way better than I could.