Mountain Safety: Glacier travel and crevasse rescue for two-person teams
Doug Latimer, ACC Lead Winter Guide
Photos by Zoltan Kenwell
This article assumes a basic knowledge of crevasse rescue systems and is not a substitute for proper training.
Teams of three or more for glacier travel are safer than teams of two where the likelihood of one person arresting their partner’s fall into a crevasse is very low.
More than a year ago I began writing a small book about safe glacier travel and crevasse rescue. Unlike avalanche safety, glacier travel does not have a national body defining best practices and promoting research.
There are a lot of details about crevasse rescue that mountaineers should know – far more than can be covered here. For this article, I would like to bring attention to arresting a fall and crevasse rescue for a two-person team.
You won’t hold the fall
First, let's kill the idea that a single person can reliably hold the fall of a second rope member into a crevasse. If you’d like to see it attempted in a controlled setting, check out this video by a Czech guiding company: https://bit.ly/CrevasseFalls
Crevasses can be visible, or they can be covered in seasonal snow. Friction knots can improve the chances of arresting a fall, but only in certain snow conditions.
Yes, there are cases when a single person arrests a victim falling in a crevasse (I've done it once), but the probability is low and it hurts like you wouldn't believe. The bottom line is that a two-person rope team using traditional skills has a dangerously high probability of catastrophic failure when one member falls into a crevasse. What surprises me most about the above statement is how long it took climbers to realize this. Traditional rope systems are simply not adequate for two-person rope teams.
Adding friction knots
Fortunately, the Europeans are way ahead of us and have developed a new strategy: tying friction knots on the rope between the two members of the team. When a fall occurs, these knots bite into the snow and create friction that significantly reduces the force transmitted to the rescuer. Utilizing friction knots, a two-person rope team has a realistic chance of surviving a fall in favourable snow conditions. The effectiveness of these knots can be seen in this video, produced by the French guiding community: https://bit.ly/ BrakeKnots.
While researching the material for my crevasse rescue book, I didn't have anyone jump into a crevasse, but I did measure the amount of force transmitted through the rope to hold a 100 kg person. Once the friction knots set, the load on the surface was only 22 kg. These knots work.
Unfortunately, knotting the rope creates new problems. Most crevasse rescue systems utilize the same section of rope the victim is hanging from for the rescue – either by prussicking, or by winching up. The existence of friction knots in this line makes both self-rescue by the victim via prussicking, and winching the victim up, next to impossible. Friction works both ways.
Crevasses are the single biggest danger of glacier travel.
If you are using friction knots it becomes essential to have either a separate rope or extra coils from the existing rope available to perform a crevasse rescue. The drop loop rescue system is simple and effective, but requires a bit more than twice as much rope as the distance between each rope member. For two-person rope teams, the minimum recommended distance between climbers is 15 metres. A party of two using a 60 m rope with friction knots does not have enough free line for both team members to perform a drop loop rescue without a separate rope and therefore your rescue system becomes more complex.
Other considerations
This would be a great solution if that was all you needed to contend with, but unfortunately, it’s not. Keep in mind that all mechanical advantage numbers for rescue systems (2:1, 6:1) are theoretical, not practical, even under ideal conditions. And then there are a bunch of other real-world problems that complicate things like snow anchors (which are poorly understood) and direction of pull on the anchors.
In short my tiny little crevasse rescue book keeps putting on weight and taking longer than expected to complete. While frustrating, this is a good thing. We need to better understand the strengths and limitations of our systems and equipment. From there we can develop standards and produce best practice guidelines for the ACC and mountain community in general.
In summary
Friction is good when falling into a crevasse, so put knots on the rope. But friction is bad when trying to extract the victim, so have a rescue rope, use pulleys and efficient capture devices, and minimize contact with the snow. Keep learning, and make sure your skills are current before you set out.
Dig deeper
My crevasse rescue book will be available online at www.shadowlightproductions.ca and I have already begun to adapt these standards into the crevasse rescue courses taught by the ACC national office. ACC members and sections are welcome to contact me through my website regarding training. It is my hope that we can define the standards and best practices for glacier travel and crevasse rescue throughout North America. ~ACC
As the ACC’s Lead Winter Guide, Doug Latimer teaches our instructional courses on Avalanche Safety and Crevasse Rescue, and guides our backcountry ski camps. Doug runs a video and multimedia company and is the author of Avalanche! The Guide’s Guide to Safer Travels in the Mountains.
