Monday, January 9, 2017

Are Avalanche Airbags Effective in the Eastern US and Canada?

Here at Mammut we sometimes get contacted about what our stance is on avalanche airbags in the Northeastern US and Quebec, Canada.  The topic came up again recently, so I put this together to give people the relevant information to judge for themselves.  I also wanted to hear from some experts on the subject and see what thoughts they had. It's turned out to be a bit lengthy, hopefully some of you find this helpful because we think the conclusions are valid anywhere, not just the East.

First, some of you may be thinking that "Eastern avalanche terrain" is an oxymoron, and herein lies some of the issue.  Many Eastern skiers spend much of their time in areas that simply aren't avalanche-prone, and because of this it's completely normal for many backcountry skiers to not carry any avalanche rescue equipment.  But, as Frank Carus, the acting Lead Snow Ranger for the Mount Washington Avalanche Center (link) points out:   "We have plenty of places where you can get buried".
The North Face of Gothics in New York's Adirondacks is a popular spring ice and snow climbing route, but occasionally holds enough snow to get skied, or to avalanche.

The Northeastern US and Quebec are both speckled with terrain that has become popular with skiers and riders, areas that in some cases are remarkably similar to the Rockies and the West that is more typically associated with avalanche terrain.  Every couple years there are avalanche accidents (link), including fatalities (link), across the region to prove this point.
One issue that Carus and others wrestle with is the perception among some people--even those who are aware of Eastern avalanches--that even though the East has them, that "Eastern avalanches are different".
 A common misconception is that Eastern avalanches are rarer than their Western counterparts and have such a high incidence of trauma, with such a low chance of being buried, that equipment such as an avalanche airbag is deemed ineffective by some people--even those who do regard a beacon, shovel and probe as essential and effective in these areas.

It makes sense that if a higher portion of fatalities are from trauma in the East than in the West, that any rescue gear (including airbags as well as beacon, shovel and probe) will be less effective at preventing injury or death.  Bruce Tremper of the Utah Avalanche Center addressed this on the UAC Blog (link), and used this diagram to describe in general terms the effect that "consequential terrain" (including both trauma-causing stuff like trees, rocks and cliffs, as well as terrain traps resulting in deep burials) has on the effectiveness of an airbag or a beacon:
This diagram reflects in a general sense how various types of high-consequence terrain might degrade the effectiveness of an airbag or an avalanche beacon.  Courtesy of Bruce Tremper/Utah Avalanche Center

However, short of saying that the overall statistical effectiveness of an airbag or a beacon is reduced by consequential terrain, it's difficult to quantify this or to generalize for the entire Eastern US and Canada.

So what is the real story on how people are hurt or killed in Avalanches specifically in the East? The answer isn't as clear as people would like. There are numerous scientific studies examining the cause of death among avalanche fatalities in other areas.  Most studies (link) point to something around 25% of fatalities being caused by trauma, with some heavily forested areas coming in a bit higher (link).  Despite this overall data showing that roughly 25-35% of avalanche fatalities are due to trauma rather than  burial and asphyxiation, researchers have shown that avalanche airbags are still an effective tool to reduce avalanche fatalities--the most recent study (link) shows that avalanche airbags reduce the rate of fatalities among avalanche victims from about 22% to about 11%, or about a 50% reduction in mortality. Unfortunately, even though we know there is variation in this between regions, there is very little information specifically addressing the Eastern skier or rider.

 Jonathan Shefftz is an avalanche instructor who has published in the American Avalanche Association's The Avalanche Review on the assessment of avalanche fatalities, including airbag effectiveness.  Shefftz also compiled a list of Mt Washington avalanche fatalities, which he included in his 2014 presentation at the Eastern Snow and Avalanche Workshop on airbag effectiveness.  Mt Washington is probably the most popular avalanche-prone area in the East, so it is where much of the data we have comes from.  He found that historically, almost 80% of the  fatalities on Mt Washington involved trauma--essentially the inverse of the worst national and global statistics.  However, this is a very small data-set that, from a skiers perspective, is skewed by climber avalanche fatalities in Huntington Ravine and very early-season Tuckerman Ravine (before the floor of the ravine is filled in with snow).  
"Among other things, on Mount Washington many of the fatalities are climbers, some of whom were soloing" [i.e. without a rope], says Carus.  The reason this is significant is that climbers are typically in steeper terrain and frequently involved in avalanches when they get swept off a low-angle ice climb mid-route, and therefore have a higher proportion of trauma-related injuries due to a lengthy fall.  Indeed, only 3 of the 14 recorded  avalanche fatalities on Mt Washington involved skiers.  Statistics from other regions also show that avalanche accidents involving climbers do show a significantly higher ratio of trauma than skiers, for instance the Canadian study linked-to above cites a trauma ratio for climbers almost double that of the overall rate.  This factor skews the data if we are concerned with the effectiveness of an airbag for a skier or rider.  
"There also just isn't enough data in the first place" says Carus.  To illustrate this, the historical trauma percentage of all recorded Mt Washington avalanche fatalities was increased in Shefftz's  analysis from 64% to 79% simply by reclassifying one accident in which 3 people perished because, while it's true they were buried and probably suffocated, the accident was complicated by additional trauma. Much more data would be required to come up with a meaningful prediction for avalanche fatalities among skiers caused by trauma, and thankfully we don't have that data.  Shefftz cautions that "The only thing we can say for certain from the historical statistics is that some of those avalanche fatalities on Mt Washington would most likely have been prevented by a deployed airbag".  
Nevertheless, it seems fair to say the ratio of trauma versus asphyxiation deaths could be higher than the continent-wide rates, which will surely reduce the statistical effectiveness of any rescue or safety equipment.  So how to put this in perspective? 
A skier-triggered avalanche crown and debris-pile in Mt Washington's Gulf of Slides.  This slide definitely could have buried a person, with trauma possible but not a certainty.  Photo courtesy of Andy Stone

The relevant question for the individual Eastern skier wondering whether to buy an airbag is exactly how much any terrain-related reduction in effectiveness of their equipment will affect them in the places they ski or ride. To answer this question it's important to keep in mind that other regions have trauma issues as well, and that because terrain is always the deciding factor it's up to each of us to manage these risks. 
     "This attitude some people in the East have that "the West" doesn't have trees and rocks and the same types of consequential terrain we do here," Carus goes on to say, "well, it's just not true. There's tons of trees in the West, too. Whether or not you are likely to get buried, and whether an airbag or a beacon has any chance of being effective, depends on exactly where you are, what the avalanche problems are on that day, and how filled in the terrain is [with snow]" Carus says, "and that's not just an Eastern thing".
This screenshot from January 2017 is just one example of Western avalanches every year in consequential terrain.

Mark Synnott, of Synnott Mountain Guides, agreed on that point.  Synnott says he's always a late-adopter of technology, but that he now has an airbag and plans to use it selectively on Mt. Washington depending on the exact conditions and terrain. In areas where any avalanche will be above unavoidable higher-consequence terrain such as trees or exposed rocks, he said he thinks the airbag is probably of little use and he may not carry it, while in other areas he will use it. "The whole thing about airbags not being useful on Mount Washington is wrong" he says.  "I haven't skied with an airbag here or anywhere else in the past because the ones I've tried have been really heavy, but that doesn't mean they wont work.  Almost all of Tuckerman Ravine, some of the Gulf of Slides, and most of the big ravines have plenty of terrain with a good runout.  It's going to depend on the snowpack and how filled in it is, but if there's snow it's runout almost all the way".   It's noteworthy that these areas also happen to be among the most popular ski runs.

Steve Charest (link), a certified ski guide and avalanche instructor based in Vermont, says he also wears an airbag in Eastern avalanche terrain much of the time.  
     "I don't carry the airbag in Smugglers Notch because there's trees and rocks below everything" he says.  "I also don't wear my airbag ice climbing, even on Mount Washington, because if a slide knocks me off Pinnacle Gully I don't think it's going to help.  But I do wear it skiing on Mt Washington because there are a lot of cleaner runouts.  I wear it in the Adirondacks skiing slides too.  Some of the slides have pretty good runouts, but on some there's a big pile of trees and rocks and other debris at the bottom.  That's a wicked terrain trap and if I'm carried I may hit something but I definitely want to be on the top of that pile of snow" he says.  "I definitely wear it in the Chic Chocs.  Many areas on Mont Albert and Hogs Back have a very clean run.  Mont Lyall, the big scary paths have cleans runs, but the tree runs there are more BC-like [so you'd probably hit something]".  

Charest said that especially in consequential terrain one thing he stresses is before he would pull his airbag in an avalanche he would "fight my ass off" to self-arrest before he was being carried.  "Once I pull the airbag" he says, "I know I'm going for the full ride, and if there's a terrain trap or trees below I'm going to fight first to avoid being carried at all".  

Synnott and Carus both also stressed the importance of trying to self-arrest before the avalanche picked up speed.  
    "I've been caught in 2 avalanches on Mount Washington" says Synnott, "both of which could have been pretty serious. In both cases I was able to self-arrest.  The first I was able to get through the slab to the bed-surface before it really got going, and the other I was being rag-dolled and carried and I knew there were trees below, so I swam to the bed and was able to self-arrest".  When Carus was captured by a heavy storm slab his first reaction as soon as the avalanche started moving was to get to the bed-surface and try to self-arrest, which didn't work due to the weight of the debris.  His current thinking is that as soon as he was being carried along by the avalanche he would have triggered his airbag to aid his efforts to swim to stay on the surface and hopefully stay on the uphill end of the flow. 

Carus said the Mt Washington Snow Rangers generally use airbags unless it's a spring snowpack that is deemed safe or for operational reasons where it is not possible.  "In the places where you can get buried, an airbag pack can help you" Carus says.  "It also doesn't work if you don't wear it" he points out.  "It only takes being wrong once, and all of a sudden you're there without your airbag.  We wear them most of the time [that we can], but we don't rely on them for our safety".
Skiers in Mt Washington's Gulf of Slides ascending next to one of the many avalanche paths that are popular ski runs  

"Not relying on them for safety" brings up the topic of risk homeostasis  (aka risk compensation), which is the phenomenon of people subconsciously increasing their risk-exposure as a result of using safety gear, which decreases the statistical effectiveness of the safety gear.  Risk Homeostasis is also commonly brought up as an argument against using avalanche airbags.  The argument goes like this:  "I'm afraid I will make worse decisions if I wear an airbag, and I'd rather be careful and stay out of trouble in the first place.  The only thing that will help me stay out of trouble is good, conservative decision making, so I choose not to use an airbag".  Ever on-point, Bruce Tremper also has a great post on the UAC blog on this topic (link).  As he concludes: 
     "Yes, most credible, scientific studies show equipment does, indeed, make us safer, but it often doesn’t provide the expected level of benefit because we tend to compensate for it by increasing our risk...So the key to getting the maximum benefit from safety equipment is to also carefully control our attitude and behavior".  
In other words, safety equipment generally does make us safer, just not as much as it could--but the net result is generally that we are safer, and as always it remains up to us to "carefully control our attitude and behavior" in order to see the expected benefit.  The common advice for checking one's attitude and behavior is to ask yourself through the day "would I be here if I didn't have my beacon on"?   This is a good self-check that Carus and others also mentioned as one way to self-regulate any risk-compensating behavior.  

Skiers in Mt Washington's Tuckerman Ravine, one of the most popular avalanche-prone backcountry skiing destinations in the East.  One skier is exiting Right Gully, the other is in the distance above the Lip just below the low-point in the sky line.
So, what do we know for sure?
1) We know there are avalanches in the east big enough to bury a person
2) We know that globally and nationally avalanche airbags are effective, reducing mortality by about 50% (from 22% to 11%), despite trauma being a significant factor in nearly all regions.
3) We know that consequential terrain degrades the effectiveness of all rescue equipment, both airbags and beacons.
4) We know the fatality info we have from the Northeast is suspect as a predictor of cause of skier deaths in avalanches, being a very small data set skewed by being largely comprised of non-skiers in what is commonly not viewed as ski-terrain.  
5) We know that all regions have consequential terrain.  Possibility of trauma in an avalanche remains a significant issue that must be managed through terrain choice, regardless of location.  We THINK it's reasonable to say the trauma-percentage of fatalities may be higher in the East than in the Rockies or West, but we cant really say by how much.  
6) We know that all of the 4 experts on the subject I asked said there was commonly skied terrain in the East that can produce avalanches large enough to bury a person, but is typically "clean" enough that major trauma is not at all a certainty, lending some degree of usefulness to rescue equipment such as beacon, shovel, probe or airbag.

So, based on this, what is Mammut's recommendation for Eastern skiers and riders?  
We think the TERRAIN is really what dictates the actual chance of any of this equipment having a chance to work properly should you need it.  Is there terrain in the East where an airbag is unlikely to prevent injury or death in an avalanche?  Yes, there certainly is.  This is true in any other region of the world as well.
Yet, according to everyone we spoke with there IS good, less-consequential terrain in most of the Eastern areas prone to avalanches.  

Based on this, no one can make a blanket statement that an airbag is ineffective in the East, since that's largely dependent on terrain choice and conditions that we've already heard do exist.  We can't really make an accurate comparison to other regions, so for now we're forced to rely on qualitative assessments of effectiveness.  In this regard, we don't consider an airbag in the East any different than an airbag in the West, or the Alps or anywhere else--every region has terrain where an airbag or a beacon has little or no chance of helping you in an avalanche, and every region has terrain where it probably will help.  The key is for each of us to identify those areas and make educated, objective decisions about the particular hazards of any slope to decide whether we want to be there in the first place and whether an airbag is worthwhile.  

In other words, YOU determine not only how likely you are to be caught in an avalanche, but also how effective a beacon or an airbag might be--in the East or anywhere else--by choosing less-consequential terrain and conditions.   It's up to every person to decide for themselves if the weight, the cost, and the effectiveness of an airbag on any given day is worth it for them.  

As Tremper put it in his airbag blog post (link)
"If you get caught in un-survivable terrain then, guess what, you won’t survive no matter what kind of rescue gear you use...In zero-tolerance-for-error terrain [Mammut note: i.e. anywhere significant trauma is very likely in an avalanche], airbags don’t work, beacons don’t work, Avalungs don’t work.  Nothing works.  Save your money, buy a life insurance policy" 
The opposite of this is also worth pointing out.  If a beacon, shovel and probe ARE going to be of any use in conducting a successful rescue of a live victim (outside of specific cases such as a slide from above while in a terrain trap) then an airbag can also have a reasonable chance to successfully prevent or reduce the depth of that burial. While many people consider a beacon, shovel and probe mandatory (link), an airbag is generally considered optional. For someone considering adding an airbag in addition to a beacon, it doesn't makes sense to say one is helpful and the other isn't, if there is a reasonable chance of either one preventing a fatality--both of them have the best chance of helping you in the same type of terrain.  

It's our opinion, and we think also clear from talking to people that work and spend lots of time in Eastern avalanche terrain, that with the right attitude and terrain choices there definitely IS a place for avalanche airbags in the East, and that under the right conditions they can be an effective tool to help you stay as safe as possible.  As Carus pointed out, "You can be careful, you can manage terrain as well as you can to avoid consequential areas, but if you spend enough time out there you can still get in trouble.  Even experts get caught".

Note:  Several people that I've showed this to immediately asked about Mammut's Protection Airbag System (PAS), the shape of which is designed to protect the user from trauma.  Mammut's claim of trauma protection is based in large part on a scientific study which can be found here: LINK.  In short, this study showed that the shape of the protection airbag (represented in the study by the LIFEBAG, which is the same-shape predecessor of the PAS) reduced the g-forces measured on the head and neck of a dummy in an avalanche roughly in half.  Although some other manufacturers claim some degree of trauma protection, no other airbag shape has been shown to provide this effect.  Research from the automotive industry correlates this reduction in g-forces with a reduction in traumatic injuries.  Obviously major trauma wont be completely avoided, but the intention is that providing some protection in a survivable avalanche could be the difference between significant injury and needing an organized rescue versus skiing away with only minor injuries or just bruises, or perhaps preventing you from becoming one of the victims who perished from asphyxiation due to complications from less-severe trauma.  Of course avoiding trouble in the first place is always the only certain way to avoid injury. 

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