How avalanche air bags work in theory/ABS Technology

Possibility safety gear might up danger

Thirty-two-year-old Eric Walter was wearing an avalanche airbag when he triggered a snowslide in Denali National Park early this month, National Park Service officials have now revealed.

He did not survive despite being outfitted with what has been a widely considered a revolutionary piece of avalanche safety gear.

“The effectiveness of avalanche airbags is impressive,” SnowBrains, a website focused on avalanche safety reported in the winter of 2021. “In a study of 85 accidents by the American Mountain Guides Association, airbags reduced mortality by 92 percent in the backcountry.”

The story paid lip service to the fact that “the best way to survive an avalanche is to prevent being caught in one altogether by applying proper decision-making skills when selecting descents.” but added that “this is not always the case due to the extremely unpredictable nature of avalanches.

“That’s why having an avalanche airbag is so crucial. Because although they tend to be pricey, no amount of money is ever too much when you consider the fact that it could be the deciding factor as to whether you live or die.”

Early data on airbags coupled with regular reports of airbags saving lives have led some, if not many, to think of the bags as near foolproof.

“January 8 was a spectacular day for large avalanches,” the Colorado Avalanche Information Center reported in December 2021. “In one day, a group of riders remotely triggered a very large avalanche on Grouse Mountain outside of the Beaver Creek Ski Area boundary, which was caught on video. Then in two separate events, which were also both caught on video, a snowboarder was caught in a large avalanche on Loveland Pass where he deployed his avalanche airbag and ended up on the surface” while a snowmachine rider in managed to outrun a separate avalanche. 

Norwegian Olympic skier Hedvig Wessel was skiing in Alaska in April of this year when she triggered a slide that “caught up to her and she momentarily lost sight of the sky. Her survival instincts kicked in and she immediately pulled the ripcord on her avalanche backpack with inflated successfully,” Unofficial Networks reported.

The story came complete with Wessel’s self-shot video of her being caught in the snowslide.

“Looking back, I am grateful for this experience, and everything I learnt from it,” she said. “I am grateful to come out of this with no injuries. I am grateful to have equipment I trust and know how to use. I am grateful for my team who makes me feel safe and supported.”

Far from perfect

There is no doubt airbags have saved lives, but as James Pavelick writes at Rise & Alpine, “airbag marketing companies latched on to the 97 percent survival rate of those wearing an airbag. But, these numbers can be spun in all sorts of different ways….”

And newer research has raised questions about just how effective the bags.

A peer-reviewed study published by European researchers in the Journal of Travel Medicine in November reported a rise in avalanche-related injuries and death during the “COVID-19 pandemic as ski resorts shut down” and warned that while the bags appear to make skiing in avalanche terrain safer there is “a scarcity of reliable scientific research on the topic, and the way in which airbags reduce mortality and to what extent is still debated. Several elements seem to influence airbags’ efficacy, and their use still yields several limitations linked to manufacturing, proper use, user education, and risk compensation.”

The latter issue – risk compensation – is a problem too often ignored with safety gear in general though it has often been noted in studies of why safety gear isn’t working as well as hoped.

Researchers who in 2007 ran children ages seven to 12 through an obstacle course with and without safety gear concluded that “the time it took the child to run through the course and the number of reckless behaviors (e.g., falls, trips, bumping into things) that the child made while running the course…indicated that children went more quickly and behaved more recklessly when wearing safety gear than when not wearing gear, providing evidence of risk compensation.”

The peer-reviewed work was published in Accident Analysis & Prevention under the title “Understanding children’s injury-risk behavior: wearing safety gear can lead to increased risk taking.”

The issue applies to adults as well as children. Researchers studying cyclists in 2011 reported in peer-reviewed Risk Analysis, the official publication of the Society for Risk Analysis,  “that those who use helmets routinely perceive reduced risk when wearing a helmet, and compensate by cycling faster.”

And in December 2020, the peer-reviewed Journal of Outdoor Recreation and Tourism published a study specifically asking the question “Do avalanche airbags lead to riskier choices among backcountry and out-of-bounds skiers?”

The researchers reported conducting “an extensive online survey including a discrete choice experiment to approach the topic of avalanche airbags and risk compensation from multiple perspectives. Our study sample consists of 163 airbag owners and 243 non-owners mainly from Switzerland, Germany, and Austria.

“The analyses of the survey responses provide both indirect and direct evidence that risk compensation in response to avalanche airbags is likely within at least certain segments of the recreational backcountry and out-of-bounds skiing population.

“Finally, our analysis of avalanche involvement rates with and without airbags offers the most direct evidence that more thrill-seeking backcountry users are taking higher risks when equipped with airbags.”

Vital equipment but….

The researchers conceded that the airbags designed to float their wearers to the surface in the event they are caught in an avalanche are one of the best means of preventing deaths in such incidents.

But they went on to warn that because of the way airbags are viewed “the topic of risk compensation should be included in avalanche awareness courses and discussed in avalanche airbag support documentation and user manuals to increase the awareness of the potential among users.

“Risk-taking in the backcountry is a personal choice, but recreationalists should have the necessary information about the direct and potential indirect effects of safety devices to make informed decisions.”

The researchers noted that 96 percent of the airbag-owning skiers and snowboarders asked their reason for buying a bag responded that a “higher chance of survival (WAS) important or very important for their purchase.”

Walter would likely be classed among that group. All indications are that he obtained an airbag in the interest of safety, but it couldn’t save him.

He is not alone. Wilderness Medicine Magazine reports that “up to 1-in-9 studied avalanche victims who deployed airbags still died. Roughly 80 percent of those victims suffered complete/critical burial despite using their airbags, while 20 percent were killed by trauma alone.”

Walter’s cause of death has not been reported. He could have died as the result of blunt force trauma in being tumbled down the mountain or ended up suffocating face down in the avalanche rubble even though his airbag deployed.

The latter would be especially unfortunate given that in such situations people are regularly saved by their ski and snowboard companions. Walter was alone, but he probably thought he was safe right up until the time he wasn’t.

He was skiing a north-facing slope, according to reports, and north-facing slopes, which are exposed to less sunlight than south-facing slopes, are generally the safer slopes to ski in Alaska in May, and he was wearing that airbag.

He had reasons to believe he’d minimized the risks of dying in an avalanche. But, as it turned out, he hadn’t. Unfortunately, no one will ever know how much the airbag influenced Walter’s decision to challenge a slope along the Denali Park Road on the day he died because he isn’t alive to answer that critical and lingering question.