Avalanches and Heuristic Traps

night skiing, fullmoon, Stevens Pass, Washington, Cascades

Stevens Pass on a fullmoon night.

The New York Times has published an engrossing article, Snow Fall: The Avalanche at Tunnel Creek, by John Branch documenting last year’s tragic avalanche accident at Stevens Pass in Washington state.

The article hits home for me, not just because I’m an avid backcountry splitboarder concerned about avalanches, but also because I spent the entire 2001-02 winter season working/bumming at Stevens Pass and have ridden the Tunnel Creek terrain many times. This article delves into the story in a much deeper fashion than the usual avalanche accident reports, providing background of the circumstances, the conditions, and most importantly of the people involved. The website also provides thorough multimedia integration to tell the whole story as clearly as possible. It was a truly tragic day, and the article is well worth a read for anyone who ventures into the winter backcountry.

One aspect of backcountry travel that the article hits on is the concept of group dynamics and how that can affect backcountry safety. A while back I read a very interesting and surprising report about this: Evidence of heuristic traps in recreational avalanche accidents, by Ian McCammon. “Heuristic traps” basically means poor decision making due to unconscious social reasons. The study is based on statistics compiled by the CAIC (Colorado Avalanche Information Center) from 622 avalanche accidents over 30 years. Here are the key points from the study to consider every time you head out into the backcountry snow:

• The safest group sizes tend to be 2-5 people, with 4 being the safest. Groups of 6-10 are just as hazardous as 1.

• For all levels of training, everyone tends to be slightly safer in unfamiliar terrain. Groups with advanced avy knowledge stand out as being the clearly the safest in unfamiliar terrain, and actually the least safe in familiar terrain!

• The mere presence of people outside the victims’ group correlated with a significant increase in exposure to avalanche hazard. Again, especially so with advanced-trained groups.

The group involved in the Tunnel Creek accident hit all three checkboxes: a large group of experienced skiers in familiar terrain with presence of outsiders (the place is a very short hike from the ski resort). The power of these heuristic traps is evidenced in the NYT article by some of of those involved who said that they had doubts and misgivings at the top, but didn’t say anything (because of the social influences of being in a big group).

“Traditional avalanche education places a heavy emphasis on terrain, snowpack and weather factors. While there’s no doubt that this knowledge can lead to better decisions, it is disturbing that the victims in this study that were most influenced by heuristic traps were those with the most avalanche training.” ~ McCammon

Tragedies like the Tunnel Creek accident underscore the importance of keeping a conscious attention to not only the snowpack behavior, but our group and personal behavior as well in order to maintain objective and rational decision making in potentially dangerous circumstances.