Crevasse Rescue Part I, and our first flight delay!

Hi Friends,


We spent this afternoon practicing techniques for pulling someone out of a crevasse. When we travel over unknown terrain that has the potential for crevasses, we will "rope up" into two teams of three. We will use two climbing ropes, each ~ 60 m long. Three people will be attached to each rope: one at each end, and one person in the middle. If the first person falls into a crevasse, the two people at the back of the rope use an ice axe to "self arrest" or stop themselves in the snow. Tomorrow, we're going to practice this skill set outside, so I can explain it more clearly in tomorrow's post! This afternoon, we focused on how to use ropes (a) to climb out of a crevasse if you fall in, and (b) to pull your friend out of the crevasse if s/he falls in.

First, Chris gave us an introduction to the ropes we will be using. These climbing ropes are "dynamic" ropes which means they are made to stretch a little bit when pulled on. Chris is also instructing us what not to do with a rope; do not step on the rope! Especially with crampons on! Stepping on the rope could compromise its integrity. More about crampons tomorrow!

Chris hung three ropes from a beam in the ceiling so that we could practice climbing up the rope as we would need to if we fell in a crevasse. 

The first step to simulating roped glacier travel is to tie a figure eight knot "on a bight," or on a loop of rope.  This knot is then attached to our harnesses using a locking carabiner (see the picture below). 

 So, if you fall in a crevasse, and your friends "arrest" or stop your fall; you'll find yourself dangling by your harness inside the crevasse. All of your weight will be pulling on the knot in the picture above. While your friends are scurrying around on surface of the glacier, trying to set up a hauling system to pull you out - it's your job to climb up the rope if you're physically able.

Fortunately, your harness and your friends' harnesses have all sorts of helpful tools on it. These tools are attached to our harness with carabiners. Clockwise from the top: two prusiks (the yellow and blue cords), a sling (or loop) of webbing (in red), an ascender, a pulley, and an ice screw. For the purposes of climbing up the rope, the prusiks and the ascender will be your tools. 

Here Chris demonstrates the two tools you can use to climb up the rope!  The ascender, the metal tool in Chris' right hand, has a special gripping mechanism that allows rope to pull through in only one direction. When you attach your harness to the ascender, you can hang on the ascender and you will not slide down, but the ascender will allow you to move it up or ascend the rope.


The word "prusik" refers to one of the hitches you can tie with the loops of cord shown in the previous picture.  In the picture above, Chris is demonstrating the klemheist, which is similar to the prusik hitch.  Both are friction hitches. Friction hitches take advantage of the friction at the contact between the prusik cord and the climbing rope. As with the ascender, a properly-tied friction hitch allows you to hang from the friction hitch (it will not slide down the rope), but you can move the friction hitch up the rope when you are ready. 

Here, Chris is pulling down on the klemheist - notice it is not moving down the rope! 

Here, Chris is demonstrating how you can move the hitch up the rope when you are not pulling down on it.

These friction hitches are strong, and a common tool used to climb up the rope out of a crevasse. Here is Seth hanging from a klemheist. 

Matt is preparing to climb the rope. If he were hanging in the crevasse, he would have to reach around to the loops on his harness and remove the ascender and the prusik cord. In this picture, he has attached the ascender to the rope and to his harness. He is working on attaching a prusik cord to the rope using the klemheist. 

With the prusik cord attached to the climbing rope, Matt now has two tools attached to himself and the climbing rope that will help him climb the rope. Notice that he has his foot in the prusik cord. When he pushes up on his foot, he will relieve his weight from the ascender, which will allow him to push the ascender up the rope. 

Up!

Up!

On another rope, Seth has made it to the top! 

For the second half of the class, Chris taught us what to do while our friend is busy climbing up the rope inside of the crevasse. While s/he is busy climbing up the rope inside of the crevasse, we are busy trying to pull him or her out!

Once the other two climbers on the rope have self arrested and have stopped their friend's fall, the two climbers on the surface need to build an anchor that they can attach the rope to. In the picture above, Chris is looking toward the "crevasse" from an anchor he has simulated with black webbing in the lower right corner. This anchor would be a "dead man" anchor like the kind we use to anchor our tents.

Once an anchor is secured, we can transfer the weight of our friend in the crevasse to the anchor and free ourselves to build a hauling mechanism. Using carabiners and pulleys from our harness, we can increase the mechanical advantage of the hauling system and reduce the force we will have to exert to pull our friend out of the crevasse. 

Greg is serving as the friend in the crevasse. 

Greg and I used the system pictured above to haul Seth out of a "crevasse."

Tomorrow, weather permitting, we will practice these skills in McMurdo's crevasse simulator! Which brings me to our first flight delay - we've been informed that our first cargo flight will not leave tomorrow, as planned. Instead, our first cargo flight should leave on Wednesday the 14th. 

We'll keep you posted as our plans adjust!

Hope all is well at home!

Claire