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Decision Making in Avalanche Terrain: Pt.I - Strangers

Henry
12 minutes ago
6 min read

What does avalanche decision making actually look like in practice?

In this special three part series, I review three incidents that sparked conversations about avalanche safety, in my head and amongst my friends, when out on the slopes.

By breaking down these episodes, we can learn much about avalanche safety; but, perhaps more importantly, we can begin to understand what decision making in avalanche terrain actually looks like, something we're told to do in avi courses but may not have the tools to do straight away.

Introduction

Sitting on the Cascade chairlift high above Val d'Isere, we pulled our layers, collars, and hoods up around us; the wind was fierce, blowing straight up and over the Pays Desert (or “deserted land”) off to our right.

Looking dead ahead of us at the face of the now-almost-completely extinct Pisaillas Glacier, we examined the traverse tracks heading away from the top of the lift; looker’s left to the Pointe and Aiguille Pers, and the Pers Glacier beyond, and looker’s right, out along the wall high above the Pays Desert and up towards the l‘Ouille Noire.

Both of these tracks were well established, but had been buried in parts under the avalanche debris of the night before. Looking left, a large slide had cover the Pers track, and we witnessed a new group, sensibly, breaking trail on more serene terrain further down the face.

Tearing our focus away from this setting scene, we raced down the pisted reds underneath the glacier as a warm up run – firm, fast, grippy, corduroy heaven - then hopped back on the Cascade lift. Not 10 minutes had past since we had first sat there and noted the original avalanche paths. In that time, two more slides had popped off, one over the traverse path to the left, and one over the traverse path to the right, immediately next door to the first slide.

And yet, still the tourers pushed out along the avalancbe-riddled traverse paths. We set out ourselves, following a traverse path set much, much further down the face out to the chairlift’s right, well well out of avalanche danger from any slide that might pop off above us.

What really triggered our conversations about today? As we approached the dual avalanche paths noticed from the Cascade’s chair, we saw a group of tourers heading up the slope, trying to get to the top of the ridgeline down which all this avalanche activity was happening. At first glance, we thought this the stupidest decision we had ever seen anyone make since, well, about two days before. What on earth is going through their minds to tour and bootpack up a really steep face that you know is an avalanche risk because … well, it’s basically avalanching around you?!

But there was more to this decision than meets the eye. As we got closer, we stopped, examined their path choice, and stepped back from our initial judgements, assessing strangers' choices in avalanche risk terrain.

The Four Factors

Let’s examine the four factors that we know influence avalanches and avalanche activity, and how they’ve chosen to avoid or mitigate them.

The snowpack is generally stable on north facing slopes, information we’ve acquired from digging a snowpit – something we actually did right after this event. Most of the faces that had already slid, however, were not north facing, but angled slightly round to west. This means they would have caught the sun in the late afternoon, when it was strongest, and formed a nice crusty layer on top. The avalanche forecast for today was advising about just this risk.

At the same time, we were witnessing the snowpack transition before our very eyes, from a winter snowpack – where weak layers and dry avalanche problems are the main issues - through to a spring snowpack. As the snow begins to melt, it increases the volume of water in the snowpack, and you get what are known as wet avalanche problems – hard freeze-thaw slab, or meltwater acting as lubricant in place of facets.

Look closely - a group of skiers pick their way up a risky slope

It was clear that the faces that had already slid were those angled away from north, susceptible to these wet avalanche problems that had sprung out of nowhere.

By contrast, the faces these guys were touring up were one of two things;

Avalanche paths, which we know once slidden do not slide again until reloaded with snow, making them safe
North facing slopes that were less likely to slide

In addition, the slopes that had not slide were being traversed across right at the very top, where buttresses of rock loomed above the skiers; this massively reduces the risk of a quick-propagating avalanche bringing down a high volume of snow on top of the group, something that was liable on other slopes.

So this group had chosen a route that, by all intents and purposes had avoided terrain traps; crossed a theoretically stable snowpack; and crossed pre-slid slide paths.

Risk Tolerance

I want to talk about risk tolerance here, as it's fundamental to describing why we make the decisions that we do.

The skiers climbing this face are clearly experienced; it is a steep, technical face, one where you need skills and experience to get on top of and a lot to ski down - and come back out of - what's on the other side.

Clearly they are familiar with the terrain, too, or at the very least skiing with someone who is familiar with the terrain such as a guide, to understand the nuances of this face.

Most of all, however, they are confident that faces that will slide have already slid, and that those that haven't, won't. Or at least probably won't. This isn't inconsequential terrain here, either; if it does go, as we can see from the debris pile of one of the preceding avalanches, this isn't a pile of snow I would want to be stuck under.

This group were carefully, carefully picking their way up these small ribbons of comparative safety, often no wider than a few metres. North facing so stable, as low consequence as its possible to get in this environment, and going at it one at a time to risk as few people at a time as possible.

All that being said, you still wouldn't get me going up this face, is what I'm trying to say. I'm quite an experienced skier, I can handle myself in most scenarios, but you won't get me going up here, not until hell freezes over and the day doesn't end in "Y".

So why did this group? Because their risk tolerance was higher than us. Because they had the extra skills and experience to read the nuances of the slope. Because they're happy to deal with the potential consequences of their choices if it does go.

When skiing as a group, it is really, virally important to understand risk tolerance. Decisions involving risk must be taken as a group, and must be taken down to the lowest common denominator; if one person isn't happy, then no one is.

You also need an environment where people feel comfortable speaking up about their differences in group tolerance. Women are generally more risk averse than men, but in a group of predominantly men these voices often get lost amongst more brash and louder risk tolerant voices, so going out of your way to ensure every voice is heard is vital to ensure good communication and planning.

The same is true of younger skiers, who are more keen to take risks and not think about the consequences, making it even more prescient that a conscientious effort to understand and manage risk takes place.

This is also a really good example of being current with the terrain, rather than just familiar - snow and terrain can change year to year, even in places you know and love, so learning the terrain as it currently lies is critical, rather than relying on it as it was the last time you were here. This is even more true as climate change warps patterns of snowfall and cold that have shaped the winter for so many of us in the past.

Finally, planning is key. Knowing your route and the nuances of your avalanche risk are critical, but also so is adapting and changing your plans. If there's one thing running throughout these pieces, it's that preparation and adaptability is king; having the ability to call off a route but still have an amazing time is critical to ensuring everyone gets home safe.

Final Thoughts

So what did this small group of strangers teach us today? That you can still drag yourself up risky slopes as long as you are aware of the consequences? Well, yes, but perhaps in a less facetious way. Planning, familiarity with the terrain, and group chemistry and communication are all critical in establishing what risks we are happy to take, when we take them, and who we take them with.