White death

The terrifying truth behind avalanches – and what you can do to avoid disaster on the slopes

Searching for a buried transceiver on an avalanche training course, VerbierYou are being swept away by an avalanche. What does it feel like? Swimming in white powder, a mountain-sized pillow fight, surfing on snow?

Think more along the lines of a mafia burial: poured into freezing, quick-setting plaster, and left to suffocate.

I am on a course in mountain safety and avalanche awareness, and our instructor, Peter Mason – an American-born mountain guide based near Chamonix – is explaining how a falling avalanche releases energy. This melts some of the snow – which refreezes on coming to a halt.

Pete tells us about the time at guide school in Italy when his group set off an avalanche. “It wasn’t a steep slope. We were ski touring through the trees, climbing on skins, when one of the students got caught. He was somewhere flat, but above him was a little slope – and the slope went whoomph, making almost zero noise. We saw him being knocked over, and then completely buried.

“His hand was sticking out, so we could get to him and clear the snow away from his face quickly. We dug down to his torso and tried to pull him out, but we couldn’t. Even when we cleared one leg completely, and the other leg down to his boot, we couldn’t pull him out – he was screaming ‘you’re twisting my leg.’ We only released him when he was 100 per cent clear – the snow had set solid.

“He was under for only about 30 seconds, but he was already scared and choking and freezing cold. That was it for the day. But it was only a very small slide.”

Digging a snow hole on an avalanche training course

We dig a hole to examine the snow layers

According to the SLF, the Institute for Snow and Avalanche Research in Davos (www.slf.ch), about 25 people die in avalanches every year in Switzerland alone. Ninety per cent set off the avalanche themselves. Your chances of surviving fall sharply the longer you are buried: from 80 per cent after 15 minutes, to 40 per cent after 30 minutes, and just 25 per cent after an hour.

This winter began badly. Six died in the Trentino region in Italy during Christmas week when two skiers went missing – and four mountain rescuers sent to find them were killed in a second avalanche. Just after New Year, 11 ski tourers were buried in an avalanche in the Diemtigtal in Switzerland: six died, plus a rescuer killed in a second avalanche.

Pete reckons that, paradoxically, the avalanches are the result of there being less snow this season, rather than more. Early in the winter, snow insulates the warm, moist ground from the cold, dry air. If the snow layer is thin, moisture escapes easily from the ground; when it comes into contact with the snow, it freezes, forming bridges between the crystals. “The more humid the snow, the bigger the crystals; like Jenga blocks, the bigger the crystals, the worse the cohesion. And typically you’ll find the biggest crystals at the bottom.”

We dig a snow hole to look for evidence, using our collapsible snow shovels – part of the essential safety kit for skiing off-piste. Soon we have a smooth, sheer wall, about two metres deep, down to ground level.

Peter Mason, mountain guide, demonstrates snow layers on an avalanche training coursePete brushes his hand down the wall (picture, right); there are distinct layers where he can push his hand more easily into the snow. Here, the snow granules are larger; and sure enough, right at the bottom, we find the largest granules of all: a slippery layer that makes the whole snowpack unstable.

Skiers can get an idea of what is underneath their feet, says Pete, by upending a ski pole and pushing it into the snow. “It should start off easy and get steadily harder,” says Pete. “But today I can feel there are layers. And the more hard layers you find, the less stable the snow.”

We also learn how to use avalanche transceivers, before putting a couple in backpacks, burying them in the snow, and then practising homing in on the signals (picture, top of story). To pinpoint the backpacks precisely, we use collapsible probes – the third key piece of kit.

Ideally you should never need to use them. “If you’re looking for a beacon, you’ve screwed the pooch,” says Pete. We look puzzled. “If I set off an avalanche, that means I’ve made a wrong decision.”

And the best way to avoid doing that is to take a specialist course. You need to learn to identify the telltale signs of avalanche risk in the landscape; find out how the likelihood of avalanche varies with the gradient of a slope, and the direction it faces; learn to interpret the daily avalanche bulletins, and to use large-scale maps to navigate safely. You need to find out how to move safely in a group over the snow, how to identify safe zones, and how to ski in such a way that you put the minimum stress on the snowpack.

Mastering these skills could save your life. You can learn them in various ways: as part of a touring holiday with Ski Freshtracks (www.skifreshtracks.co.uk), operated by the Ski Club of Great Britain; on a dedicated course with Mountain Tracks (www.mountaintracks.co.uk); or through a local specialist mountain-guide agency such as Chamonix-based Wilderplaces (www.wilderplaces.com).