Benefits of self-arrest

A couple of very lucky people have been in the news in the last few days. Both involved slipping, sliding for hundreds of metres down icy mountain slopes, and unusually getting away with it. Reading about them both prompted a few thoughts. This post is not a criticism of either of these people, but I think their accidents help to illustrate some useful things about what can go wrong.

The first in the news was a Wellington man who slipped whilst descending from the summit of Mt Tapuae-o-Ueneku, slid about 400 metres, and managed to walk away with little more than a few bruises. This strikes me as extraordinarily fortunate. The second is the case of Victorian government minister Tim Holding, who spent two nights disoriented in freezing conditions near the top of Mt Feathertop in the Victorian alps, after he slipped off the track and slid several hundred metres. He was lucky to be found, and now he’s recovering.

One valuable quote from Tim Holding’s insights into his experience was in the above-linked article.

“I slid very, very fast and if you’ve ever slid in the ice before, you’ll know you start slowly and you slide faster and faster and you gather huge momentum.”

Self arresting is the technique of stopping when you’re sliding down an icy slope, and stopping is the all-important thing in a situation such as the one above. If you can’t stop sliding on your own terms, you’ll be stopping on the mountain’s terms which will just as likely be off the end of a high bluff or slammed into an uninviting rock-face as not. If you’re into mountaineering, you’re most likely familiar with all this stuff already. If you’re more into tramping (as I am) then it’s a very handy and sometimes essential thing to know, especially if you spend a lot of time above the bush-line.

Self-arresting is usually done with an ice-axe, and involves ramming the pick part of the ice-axe into the snow and ice, lying face down on top of it, and then to jam as much weight directly onto the adze (the flat edge part) of the ice-axe as you possibly can until it stops you…. and then hope it actually does stop you. (Don’t take this short paragraph as instruction. I’m not a qualified instructor, nor very good at all this stuff anyway. Besides, you really need to practice!) There’s a handy video that describes the technique from the British Mountaineering Council on Youtube, but you should really consult an organisation such as the NZ Mountain Safety Council or equivalent for proper training.

There’s also a technique for self-arresting without an ice axe, if you’re unfortunate enough to be without. The technique confused me when it was first explained, as I found it counter-intuitive. Summarised, the technique is to try and orient face down, arch your back and place hands and feet on the surface, then put as much weight on them as possible to try and dig in. It’s important to try and minimise surface area by keeping your stomach off the ground, since doing so will then increase the force on the pressure points that are touching, to help them dig in. (Think of your hands and feet being like an ice axe that’s digging in — it’ll hurt but there’s a better chance it might stop you!)

I found the hands-only technique counter-intuitive at first, because I usually think of more surface area as meaning more friction and a better chance of stopping. Extra surface area doesn’t work with ice, however, thanks to various physical properties of ice. You’ll just end up turning your body into a sled, getting faster and faster.

As an important side note, the most recommended way to save yourself is to avoid slipping down the ice in the first place. If you do slip, try to be holding an ice-axe before you fall, because the hands-only method is a whole lot harder to do effectively, if it’s even possible which it isn’t in some cases. Even with an ice-axe, it’s not always possible to stop, especially once you’re going really fast. Slipping is unexpected, and this quote (from the climber on Mt Tapuae-o-Uenuku) isn’t an uncommon story to hear from people who’ve survived a slide:

“I do remember the descent, I was airborne on occasion and going at speed. I was conscious all the way down, but, because of the solid ice and speed I was going, I couldn’t use my ice axe to self-arrest.”

Still, better to actually know and be familiar with the optimal techniques for stopping before they’re needed. Otherwise there’s very little chance. Practice with self-arrest techniques is absolutely necessary before they’re needed, because when it happens there won’t be time to mentally go through the process. Next time I have an opportunity in a safe environment, I might make an effort to figure out the hands-only technique.

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