Measure of Risk in Avalanche Terrain

on May 10, 2010

What level of risk is acceptable when you go back country ski touring? Acceptable level of risk or risk tolerance is very subjective. It is very personal and often based on previous experience, judgment and decision making ability. Some of the close calls that skiers live through are also a valuable opportunity to learn how to better mitigate future risks.

Risk Perception in Avalanche Terrain

Case on Mt.Brennan, Goat Range, B.C.

Nearly a decade ago, three friends decided to make an early season ski tour to Mt. Brennan in the Goat range between Kaslo and New Denver, B.C.  On its glaciated east flank they were guaranteed some good powder turns because recent storms had dumped 70cm of fresh snow.  It was late fall, October so there was very little beta on conditions available.  They were Kootenay locals, familiar with the area and super excited to go early season ski touring. 

They skinned up the towards the east glacier of Mt.Brennan and enjoyed a first run down one of its steep moraine flanks.  After a lunch break at the base of their first run, the skiers decided to ascend the main tongue of the glacier and head to the summit (2900m).  There were no obvious signs of instability (avalanche activity, whumpfing, cracking or sluffing).  From Mt. Brennan, they had an enjoyable ski descent until about half way down when the last party member fell while skiing down a thirty-degree slope.  From a fairly safe position in lower angle terrain, the skiers witnessed how this fall remotely triggered a couple of avalanches.  A nearby steeper slope completely released to size 2. This had the domino effect of sympathetically triggering the entire slope further away, to size 2.5, on the moraine flank where the group had skied their first run. Their earlier lunch spot was now buried in avalanche debris.  They carefully skied down the glacier with lots to think about on the way home.

Analyzing Levels of Risk

The skiers in this story did not know exactly how close to the hazard they were until the avalanches occurred. The direct feedback created by the proximity to these avalanches was clearly a sign that it was dangerous to ski these slopes. Perhaps if the avalanche bulletins were being published at the time, they may have been forewarned of the hazard.  Had they dug a pit (a test profile), they may have gotten significant information and considered re-evaluating their route selection.  However, had the group decided not to ascend Mt. Brennan and just skied out after their first run, they would have a mis-perception of the actual snow pack conditions and potential hazards.

This situation shows how challenging it is to know exactly how close to the potential hazard we often are and how judgment and experience can be fooled by excitement and lack of information. This is a very common phenomenon in the realm of back country skiing—we may never know exactly how close to the hazard we are until we have some sort of feedback.  Most often we have access to good information or resources to help our risk management decisions. A better understanding of the level of risk involved with our decisions requires many years of practice and experience.

What level of risk is acceptable when you go back country ski touring? Acceptable level of risk or risk tolerance is very subjective. It is very personal and often based on previous experience, judgment and decision making ability. The acceptance of risk varies greatly between cultures and personalities.  For example, Europeans tend to assume more responsibilities for the risks they take while in North America we tend to transfer the risk to make others responsible for our choices.  Technically, the magnitude of risk is a function of severity and frequency. As the severity of the risk increases, so does the difficulty of managing it, even if the risk is relatively infrequent. Back country skiing is a rewarding activity that will always have a certain level of risk associated with it. 

As a guide, at times I may choose to make riskier decisions because of valuable previous field experiences that I can draw from.  In other instances, if I don’t have substantial experience in a specific situation, I will definitely err on the side of caution.  Whether I am guiding or skiing with friends, I have no problem turning around and going home if things are more dangerous that I am willing to handle.

Decision Making in Avalanche Terrain

Our ability to make the best possible decision while back country skiing can be affected by many factors. To make better decisions in avalanche terrain we must consider the snow pack, the various weak layers, the type of terrain we are in, the weather (precipitation, wind, etc.), our group ability and our goal.  Many people have smaller windows of time to achieve their goals and this pressure affects their perception of risk.  Another human factor is our great ability to influence each other, which may lead unaware followers into dangerous situations. 

Most back country skiers strive to make the best-informed possible decisions in avalanche terrain. There are a great deal of people interested in safely traveling on skis in the back country. More people are taking recreational (AST 1 & 2) and professional (ITP 1 & 2) avalanche courses and learning how to analyze hazard and potential risk. There is also an increasing number of qualified avalanche professionals educating the public along with quality avalanche bulletins readily available for savvy ski tourers.  Despite this positive trend, there are some skiers who will knowingly make risky decisions and others who are completely oblivious to the various hazards they may be exposed to in the back country.

Experience-based decision making comes from knowing how to gather relevant information, the ability to analyze it, assess the terrain and relate this to previous experiences managing risk.  The more experience we have, the more likely we are to make better decisions that will lead to minimizing potential hazards.  Some of the close calls that skiers live through are also a valuable opportunity to learn how to better mitigate future risks. 

I was actually one of the skiers from the Mt. Brennan story.  At the time, I was well on my way to becoming a ski guide.  The more lessons and experiences I gain every season, the more I realize how much there is to learn and how much I may not have fully understood before.  This expansive funnel is a daily phenomenon for professionals who are forced to regularly assess and manage risk effectively in a variety of conditions.  In a similar way, a backcountry skier’s decision-making style and ability continue to mature overtime.

Early May and there is still snow falling in the mountains, much like early winter season… fresh powder and few people!  With less field data available, measure your risks very carefully.  My hope and intent in writing this article is for back country skiers to question their own perception of risk and how that may affect decision-making.

For more on this topic, there are many useful readings on risk, decision-making and ski touring safety in the back country, including resources from the Canadian Avalanche Association. Take an avalanche course or learn from skiing with experienced, knowledgeable back country skiers. 

Visit SMG for more information on custom or group avalanche skills training or ski touring programs around Nelson,  B.C.and ski mountaineering in N. America & Europe.

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