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Dec 06, 2025: Planning and Choosing Terrain Options
In the course of reviewing fatal incidents from the 2024-25 season for our annual publication something of interest was noted. (One benefit of preparing and/or reading these publications is to find noteworthy points that may help us improve our own risk management.)
It seems to be somewhat common for parties caught in avalanches to start out planning to "stay in mild terrain", "avoid avalanche terrain", or "avoid steep slopes".
So why do they end up in avalanches?
One problem with the statements above is that they are vague. How steep is "steep"? What exactly is "mild" terrain? And on a particular day what is avalanche terrain - over 30 degrees, 35 degrees?
Another problem is that it's too easy in the field to misjudge the terrain or to end up in terrain that would not have been accepted if specifically considered in the planning phase.
Very few incidents would be best avoided by digging snowpits or other field analysis and decisions. Certainly there are exceptions, but most would have been best avoided by better pre-trip planning.
When planning a trip for the day and deciding on terrain be specific. Exactly which areas do you consider safe that day and which will you avoid? This is typically based largely or entirely on slope angles, for avalanche purposes. (Some terrain may be ruled out for other purposes.) So consider how well you know the slope angles. Have you measured them? Relied on a map? How accurate were these methods? Allow for a margin of error.
It's increasingly common today to use apps. Keep in mind that these are not exact. They also may not accurately reflect small features, including some which can be terrain traps. They can be very useful but keep the limitations in mind. There is a previous blog post about this. (https://www.avalanche-center.org/Incidents/blog/?itemid=587)
One protocol commonly used in commercial guiding operations is for each guide to rule out terrain they feel is not safe for the day. At the early morning meeting each guide can individually and unilaterally rule out terrain. They then discuss the merits of what is left. While we generally don't use such formalities in recreational groups the idea can be applied. Each person in the group should be asked what they feel is safe and what is not.
Depending on the nature of the trip this does not need to be a complicated process. It could even be done at the trailhead if the group is familiar with the area, although it's better done before leaving home. Perhaps the night before. Earlier means more choices, including different trailheads which may not be close to each other.
Longer trips, as in multi-day, are more complicated. Usually these trips follow a specific route and the question is less one of terrain and more a matter of when to do the route and what time of day to travel. Although some sections may have a choice of alternatives.
Now that the planning has identified acceptable and unacceptable terrain it's necessary to do your best to follow the plan. If you ruled out territory don't go there, or do so only after careful consideration and discussion. You had good reasons to decide to rule it out. You can go there on another day.
Just because others are skiing or riding there does not make it safe. In some conditions many tracks can be on a slope before somebody hits the wrong spot and it slides. We archived one incident in Alaska, on Turnagain Pass somewhere, in which a guy decided at home to forego various slopes. From the road he saw numerous other people on one of those slopes and decided to go there based on that. He was the one caught in an avalanche. Had he followed his plan he would not have been caught. (Most likely somebody else would have been.)
Also beware of changes in your route, including the approach. During the past season one highly experienced group made a change on the approach due to a stream crossing which called for a variation. They later ended up in a spot they had not planned on and had to decide whether to turn back or take a route with some amount of recognized risk to get back to where they wanted to be. They chose the latter option and while crossing below steeper slopes an avalanche occurred, compounded by a terrain trap, and one did not survive.
Changes in plans and routes in the field can be problematic. This is made more complicated by the fact that the further we get from the trailhead towards some objective or destination the more likely we are to accept more risk to get there. Perhaps without recognizing, or at least appreciating, this.
You can take this as you wish, and apply it as you see fit. Different parties plan in different ways and have different risk tolerances. Just keep the key points in mind as you apply them to your own tour.
