When I returned from a mountaineering course in glacier travel and crevasse rescue that I did in August, I took some notes of the different techniques we learnt so as not to forget everything immediately again. This post is a summary of my notes extended with additional content from across the internet to make for a meatier read. It is primarily an aide-memoire for myself, but I hope it can also be useful to others as a reminder of what they might have learnt elsewhere or as an introduction to the techniques one should know before setting out on a glacier.
Before I go on, I’d like to point out that I am a mountaineering beginner. Having done a short course in glacier travel I now feel I can join a group of experienced mountaineers, but would certainly not go out on a glacier without a guide. In short, I don’t recommend just reading this post and rushing off to the next glacier you can find without the company of someone experienced.
The main risk when crossing a glacier is the possibility of falling into a glacial crevasse. Crevasses are cracks in glacial ice, which occur in areas where the glacier changes the direction or gradient of its flow. If the glacier is covered in snow they disappear from sight and become a sort of a hiker boobytrap.
You can reduce your risk of falling into a crevasse by selecting a route where the direction and gradient of the glacial flow changes less than elsewhere on the glacier, but the risk can never be eliminated. In this post I will cover the three techniques that I learnt during my mountaineering course that are used to manage the risk and limit the damage in case of a crevasse fall:
Rope teams are a means of limiting the damage should a hiker fall into a crevasse. A rope team is a group of hikers attached to each other with climbing rope via a standard climbing harness. If one of the party falls into a crevasse, the rest of the team is there to stop the fall, secure the fallen and assist in rescuing the fallen from the crevasse.
There should be 3 or 4 members in a rope team to provide enough support in case of a fall and to keep the rope manageable. The fewer people there are in a rope team the longer the rope between each rope team member should be. This will provide more time for the remaining members to arrest a potential fall. You can read-up more on roping up for a glacial crossing on getoutdoors.
If you are simply crossing a snowfield without being tied into rope or if one of your team mates falls into a crevasse and you are sliding towards the crevasse yourself, you will need to be able to stop that fall as soon as possible. There are a few different techniques to use. This BMC video shows quite well what to do.
OK, this is where we get to the serious business when things go wrong. So you’ve roped up, have been crossing a glacier, trying to avoid crevasses, but whoop one of your rope team has just fallen into one.
1. Stop the fall
Depending on how many you are and where in the group you are standing you might need to do different things. It might be enough to sit down and dig in your heals, or you might need to use some of the techniques shown above.
2. Secure the fallen
Once you’ve come to a standstill you will need to secure the fallen so that they can start self-rescuing. During my course we learnt how to build three different anchors:
- Ice screw – If you’re lucky to be on ice, this is the easiest and fastest anchor. Just screw it in and use a prusik sling (more on prusiks below) to connect the rope to the screw and transfer the pull from going from the rope into your harness to going into the anchor. This only works on ice!
- Ice axe anchor – This is similar to the ice screw system, but works on snow. You just dig your ice axe into the snow, with the shaft of your ice axe going in like a nail and then again attach the ice axe to the rope via a prusik sling. This can however be tricky if the snow isn’t compact enough, as the ice axe could be yanked out as your teammate attempts to self-rescue.
- T-anchor – This is a more secure snow anchor. Here are two videos from Outdoor Research and mikebarter387 that show how to build this well.
To get yourself out of a crevasse you need to set-up a relatively simple system of prusik slings and a pulley using the garda hitch.
I’ve tried drawing a little diagram showing how the prusik set-up works. There are two prusik slings tied to the main rope of your rope team. You tie the first shorter sling, about an arm’s length long, into your harness. This sling also has a little eyelet at the top, created by tying an additional eight knot close to the prusik knot itself (see the second part of the prusik video). The second prusik sling should be relatively long, so that you can put your foot into the loop.
The trick of prusiks is that you can move them up and down the rope if there’s no load on the sling, but if you put load onto it, it “jams” and will support your weight holding on to the main rope. You can therefore ascend the rope by pushing the two prusik knots up the rope and “stepping” into the long foot sling. Here’s a video of a chap using prusik slings to ascend up a rope.
Garda hitch pulley
Once you get close to the edge of the crevasse, the prusik method supposedly won’t work that well anymore, as the rope is likely to cut deep into the snow of the edge. This is where the pulley comes into play.
To set it up you first clip a carabiner into the eyelet of your shorter prusik sling and two further carabiners into your harness. Then you create a garda hitch using the two carabiners now attached to your harness and lead the loose end of the rope through the top carabiner. Tadaa, you have a simple pulley.
You can now pull on the rope coming out of the top carabiner and pull yourself further up the rope and over the edge of the crevasse. Here’s a video showing the whole process … unfortunately I couldn’t find one in English, but this is exactly what I’ve been trying to describe.
Based on the above, this is the gear needed:
- ice axe
- 2 slings (roughly 3 and 1.5 m long)
- 2 carabiners
- 2 express carabiners
- ice screw
- Crampons, rope teams and Zirbenschnaps. A mountaineering course on the Dachstein.
- 6 essential pieces of kit for a hut to hut trek in the Alps