Can human judgment handle avalanches? 

We're better than ever at understanding the dangers of avalanches. So why can't we avoid them?

click to flip through (6) ILLUSTRATION BY JON PARRIS - Can human judgment handle avalanches?
  • Illustration by Jon Parris
  • Can human judgment handle avalanches?

All morning, I'd heard the roar of sloughs rocketing down cliffs as I skied up a mountain in Prince William Sound, Alaska. Now, standing at the summit with my six friends and our two guides, I gazed over treeless sheets of white plunging into the inky ocean. A virgin slope beckoned us. I felt uneasy — the snow was clearly unstable — but said nothing.

I was there as a travel writer and photographer, so the group agreed that I would go first to set up my camera, accompanied by Dan, the lead guide. I shook off my nervousness and skied off, arcing turns down a mellow powder field and stopping before a knoll. Dan whizzed past me and disappeared over the bump, flanked by steeper slopes. Suddenly, a line tore across the snow, releasing a massive avalanche that crashed 200 metres down the slope, engulfing Dan in car-sized panes of broken snow that settled, slowly, into a terrifying stillness.

With the help of his inflatable airbags, Dan kept afloat and survived, unhurt. He took a few moments to collect himself, and then put his skins back on. I stood there in awe and terror, my heart racing, glad to be alive.

I don't know whether some misjudgment or breach of professional protocol contributed to this accident. It's exceedingly rare for a slope shy of 30 degrees to slide so dramatically. But for years, I have relived the incident, questioning my own assumptions about safety in avalanche terrain. Was it a wild fluke, a simple miscalculation, or a serious mistake made possible by complicated psychological factors? In other words, how dumb were we?

Over the last 10 years, skiers and snowboarders have swarmed the backcountry, thanks to rapidly improving equipment, new gates that allow access to untracked slopes beyond resort boundaries, and, perhaps, a culture that glorifies dangerous routes while minimizing risks. There are more avalanche-prevention classes and resources than ever before — in 20 years, the handful of U.S. schools has grown to more than 100  — yet the fatality rate has steadily risen since the early 1990s. On average, approximately 30 people die in avalanches in the United States annually. About a third are novices, but two-thirds have some level of avalanche training. Why are capable people making such deadly decisions? And what can those of us who emerge unharmed learn from our close calls?

"I once thought if you just give people the critical information, they'll automatically make the right decisions," says Bruce Tremper, director of the Forest Service Utah Avalanche Center and author of Avalanche Essentials and Staying Alive in Avalanche Terrain. "But I found out — just like economists and stock traders — it doesn't work that way. We human beings are not very good at logic. Our brains are hardwired for social interactions and pattern recognition." 

For decades, we have understood the basic science behind avalanches. But unfortunately, we don't make decisions based solely on observations. There are other forces at play — the emotions, biases, beliefs and mental shortcuts that some call the human factor. Relatively little empirical research has explored this, but a sweeping new study, led by two Montana State University researchers, may soon help us understand how skiers, snowboarders and others make decisions in avalanche terrain. This could change how avalanche prevention is taught, and also shed light on our relationship to risk in other hazardous endeavours, such as hiking in grizzly country or fighting wildfires.

The project, initiated during the winter of 2013-2014, asks recreational skiers and snowboarders to record their backcountry routes using an app, Ski Tracks, and then complete a post-trip survey. In the two years since it was launched, more than 400 people from the U.S., Canada and Europe contributed more than 1,000 tracks. Researchers hope to gather thousands more, but already trends are emerging. For example, experts ski similarly steep slopes regardless of whether the local avalanche forecast predicts a moderate, considerable or high hazard. (With a higher forecasted hazard, they do modify their plans slightly — avoiding, say, northeasterly slopes that could be more slide-prone.) And all-male groups typically ski steeper slopes than all-female groups on days with the same avalanche hazard, although the data on all-female groups is still small.

Jordy Hendrikx, a tall, energetic earth sciences professor at Montana State University, is leading the study with Jerry Johnson, a political scientist. Hendrikx has studied avalanche science on four continents for years, but after several friends and acquaintances died in slides, he became intrigued by the human factor.

Hendrikx says. "It's been almost an awakening for me, I realized I could spend the next 10 years researching how a particular snow crystal grows, and I'd help maybe two people make a better decision. Or I could spend the next 10 years really looking at how people interact with the landscape and how they make decisions, and I could make a much bigger impact."

I'd learned about the study in the winter of 2015-16, when I saw a request for participants on the Colorado Avalanche Information Center's website. One Saturday in March, I enrolled, downloading the Ski Tracks app on my iPhone and filling out a questionnaire about my background — gender (female), level of education (college), years skiing (25), marital status (married), number of kids (zero). At the Deer Creek trailhead near Coal Bank Pass in Colorado, I clicked on the app's tracker. The forecast warned of a considerable avalanche hazard near and above treeline — it had snowed recently and warmed quickly — but I felt safe with my husband, Andrew, my friend Rachel, and her boyfriend, Chris, all of whom are more experienced than I am.

We skinned up a south-facing slope, in air so warm we stripped to T-shirts. Little puffs of powder fell from spruce branches and, lit by sunbeams, turned to glitter. I live to ski powder — that fleeting sensation of near weightlessness — and to experience the grounding silence of a forest muffled in snow. But always, there is an undercurrent of fear. Always I am listening for whoomphs or scanning the terrain for dangerous features.

At the top of the slope, we looked out over a forested valley and an exposed white ridge, joking, snacking, drinking water and tearing the gluey skins from our skis. And then, one by one, we skied down, gleefully slicing through buttery snow and launching off buried logs. But even on this mellow slope of north-facing trees, which I had always thought of as a safe zone, I noticed the crown lines of small avalanches that had pulled away from convexities. At the bottom, a metre-long crown gaped at us — no skier tracks in sight. This small slide, about 12 m. across and 35 m. long, had slid within the last two days, without the weight of a skier.

"This is definitely weird," said Andrew. "I haven't seen that before in Deer Creek." We traversed over the top of the crown line, into a bank of trees. The next gully looked exactly like the last, but it hadn't slid. The snow sparkled in a pristine state. Andrew prepared to set off across it, and I felt a seed of unease sprout within me.

That evening, I pondered the survey questions. Did we accurately convey our observations to each other? Did we share observations freely? I thought about how, even as I realized that Andrew was approaching a potentially sketchy slope, I didn't say anything. Andrew has skied a lot more than me, and I never question his expertise. Avalanche experts call this the expert halo — a blind faith in perceived masters — and it is one of the human factors that contributes to avalanche fatalities. It is my kryptonite.

Avalanche experts have long known about the importance of psychological factors in decision making. But the Montana State University study builds on the work of one of the few researchers to analyze empirical data for evidence of the human factor.

Ian McCammon, a former National Outdoor Leadership School instructor with a PhD in mechanical engineering, knew from contemporary research that human beings synthesize patterns and devise simple rules of thumb, also known as mental shortcuts or heuristics, in order to make numerous decisions quickly. This ability allows us to do routine things remarkably efficiently, like driving and shopping. But when we use heuristic thinking instead of analytical evaluation in unpredictable, high-risk environments, it can prove deadly. And avalanche terrain is the perfect trap. It's what researchers call a poor-feedback environment. Unstable, snowy slopes remain intact about 95 per cent of the time, so terrible decisions are often rewarded with great skiing and a beer at the end of the day. This gives us confidence in our own ability, until somebody dies.

In the early 2000s, McCammon analyzed 715 recreational avalanche fatalities in the United States between 1972 and 2003, identifying six common heuristic traps. He observed that bigger groups and mixed-gender groups appeared to take more risks. People tend to find safety in numbers, and wish to impress friends or potential mates. He also noticed that skiers seemed to take more risks when they're familiar with the terrain, highly committed to a goal, competing for first tracks, or following a perceived expert.

His findings, which confirmed what the backcountry ski community had suspected for years, are now commonly taught and discussed in avalanche classes. But simply knowing about the influence of human factors on accidents doesn't appear to prevent them.

"We believe that we're rational, and we think that's the ideal largely because of the way our civilization is formed," McCammon says. "Look at all the successes that analytical thinking has brought us — electricity, cars, planes. The evidence of its power is all around us, but there's so much more to how we make decisions. We have some extremely powerful tools that we're just beginning to understand from a scientific standpoint, in terms of pattern recognition and intuition."

Those tools enabled our ancestors to survive for millennia. They just aren't so good in the backcountry. The key, McCammon says, is figuring out when to rely on heuristics and when to employ analytical systems.  

Since that avalanche in Alaska, I have enjoyed backcountry skiing less. Even on extremely mellow slopes, I am occasionally seized by irrational fear. On some level, I believe that avalanches are wildly unpredictable and could strike at any moment. That, of course, is not true. The science behind avalanches may be complicated, but it is not magical.

So far, the human-factor research has focused on fatalities, but most backcountry skiers survive. Johnson and Hendrikx hope that observing real-time decisions in successful outings will reveal how people make good decisions as well as bad ones.

"How do you teach people in avalanche courses to do the right thing?" asks Johnson. "Do you teach them by studying failure, or do you teach them by studying success? I would like to see this whole discussion shift away from accidents to positive behaviours."

On Deer Creek, I watched my husband hesitate as he contemplated crossing a virgin slope. I felt uneasy but didn't speak up for fear of seeming paranoid. Tremper had specifically told me how vital good communication is to backcountry avalanche safety, yet I still didn't speak up.

Luckily, I didn't have to. Turns out, this is a story about positive behaviour.

"Maybe we shouldn't go that way," Rachel said, nonchalantly. Andrew hesitated, pensive amid the sparkling snow. In a pocket somewhere, the Ski Tracks app on my phone was marking the moment.

"Yeah," said Chris, taking off his pack. "I'm cool with that."

A version of this story originally ran in High Country News.

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