Likelihood and Consequences

By Josh Hirshberg

We tend to think about hazard on a spectrum of both likelihood and consequences. The likelihood that a given incident will occur can range from low to high. If an incident does occur the resulting consequences could range from low to high. An example of a high likelihood low consequence event is when you forget to put on sunscreen and you get a sunburn. Similar to likelihood is the frequency at which an event might occur. A high frequency event is one that we often have lots of experience with. Take driving for example. Most of us drive all the time, sometimes at very high speeds and on treacherous mountain roads. But how often do you get in a car accident? This is a high consequence activity that we have lots of experience with and generally can manage to do safely.

So what does this have to do with avalanches? As backcountry travelers our level of experience, training, and the systems that we employ can determine our ability to effectively choose appropriate terrain for the conditions. Backcountry travelers with decades of experience have seen many high frequency or high likelihood events over the years. Novices who have been traveling in the backcountry for only a couple years may have little experience with even the high frequency events. We generally do a good job at making decision in situations that we deal with on a regular basis. Examples of a high likelihood lower consequence problems are Storm Slab avalanches and Loose Dry slides or sluffs. Even on the high likelihood high consequence end, experienced travelers are still pretty good at making decisions. Take for example Persistent Slab avalanches during an active cycle. For someone who only has only a few years of experience this situation may sound terrifying and unmanageable. The best options for this person may be to avoid avalanche terrain in the backcountry. A backcountry traveler with many years of experience and training in these same conditions can understand the nuances of the problem, plan out an appropriate route that minimizes exposure to terrain prone to this avalanche problem, and effectively facilitate their group in making decisions that will keep them safe. It’s important to have an awareness of your experience level with different situations and recognize when you are dealing with conditions in which you are inexperienced.

Low likelihood high consequence situations are challenging to both novices and seasoned veterans. Currently most forecast zones around the state are dealing with avalanche problems involving deeply buried persistent weak layers that are difficult to trigger. If you do manage to hit the right spot and trigger one of these Deep Persistent Slab avalanches, the result could be a very large slide. This low likelihood high consequence situation is scary stuff. A resulting avalanche from these conditions is something that we don’t often experience and would leave little chance for survival. Last year’s Ptarmigan Hill and Sheep Creek accidents occurred during similar conditions. As backcountry travelers, we are bad at “managing,” or making decisions, in these kinds of conditions. We don’t have much experience with them and when we make a mistake the consequences are grave. We can easily be lulled into confidence and complacency when we don’t see signs of instability or recent avalanches. It’s important to remind ourselves of the consequences of the current conditions and our inability to “manage” them. Strive for conservative terrain selection, giving your group a very wide margin for error. Go to areas where you are confident that your group can make sound decisions and select appropriate terrain to stay safe.