Abseiling: do you know the risks?

Rock Climbing Skills
08 Jul
5 min read

A common and false perception of abseiling is that it is an adventure activity that is completely safe. But accidents do occur even in controlled circumstances.

The BMC’s Equipment Failure Investigations include abseil ropes cut through, failed anchors, detached karabiners, and abseil devices that ‘mysteriously’ did not control the speed of descent.

Add to this clothing and long hair tangled in the abseil device; trips, flips and swings; the end of a rope being reached unexpectedly; plus the odd jammed rope, sharp edge and falling rock or piece of a equipment, and you have a much clearer understanding of the hazards of abseiling and why it claims lives. As with all methods of descending abseiling is dangerous; but it is particularly unforgiving of any mistakes or failures.

For most experienced climbers abseiling is an activity to be avoided unless it is the only way of getting off a climb or down a mountain - for the unwary it can be a fast introduction to discover the quickest way to reach the ground.

When to abseil

Abseiling involves descending rope(s) using a friction device (e.g. belay device) attached to your harness. It’s used to tackle terrain that would be too dangerous or time-consuming to descend on foot. For example; escaping a route beyond your ability, descending from a pinnacle, or approaching the base of a sea cliff.

Practice

If you have never abseiled before start at ground level down a shallow slope, before doing it for real. Then move on to a small cliff (not down a popular route on a sunny day!)

Anchors

Solid anchors cannot be over emphasised and should be totally reliable for a training abseil. If retreating or descending make sure the anchors are the best available and whenever possible use a second anchor point as a back-up. If the ropes are to be retrieved from below the anchors must be set up to allow the ropes to run through smoothly. Always carry tape or cord for constructing or extending abseils anchors.

Joining two ropes

For a long abseil where it is necessary to join two ropes a reliable knot must be used. Probable the most reliable is the double fisherman’s knot, but this can become jammed after an abseil. An alternative is an overhand knot but make sure the ends of the knot are long (you only want it to undo easily after you have completed the abseil).

Abseil devices

Different belay plates and abseil devices provide different levels of friction, and new and thin ropes provide less resistance than thick or older ropes: make sure you know what to expect from the combination you use. In particular take care when using a figure of eight to abseil because it can accidentally mis-align itself across the karabiner gate. If it becomes even lightly loaded when mis-aligned it can lever open and detach itself from a properly screwed up karabiner with dire consequences. At least one fatality and a number of serious injuries have resulted from this.

Making it safer

When abseiling you can easily slip and let go of the rope with drastic consequences, so it’s a very good idea to use an autobloc as a back up to hold the control rope if you let go.
The most common autobloc is a French prusik, made using a prusik loop. It’s so effective and simple to tie that there’s no need to travel without it. To make a French prusik wrap the prusik loop around the control rope four or five times. Clip both ends with a karabiner and attach that to the leg loop of your dominant hand. If you have too many turns it can be very hard to release it, so get to know how many you need. When held in your hand the knot is loose allowing the rope to slide freely, but if released it grips the rope and prevents further progress.
Remember that the prusik is not fail-safe, it could rub against something and release, so always try to keep hold of the control rope.

Rockfall and edges

When setting up the abseil avoid positions with loose rock or sharp edges in the area where the rope will run. If it is unavoidable to abseil down loose rock, with care, it can be removed to help avoid in being accidentally pulled down when the rope is retrieved. A loaded rope stretched over a sharp edge can easily be cut through, so avoid doing this if at all possible and if in any doubt use some form of rope protector.

The Abseil

Secure yourself and the ’top’ of the abseil ropes to the anchors being used for the descent. If it will not be possible to see the ‘bottom’ ends of the abseil rope tie a knot in them before carefully throwing the rope down the cliff making sure anyone below is aware you are abseiling. Position the rope to avoid any sharp edges. If the ropes are to be retrieved from below position the knot so it will not catch in a constriction as you pull it from below. Always consider using a prussik knot or other back-up system on the abseil rope in case you need to sort out a tangle, need to rest, and to guard against losing control.
Before committing all your weight to the abseil ensure that your belay device and screw-gate are properly aligned. Abseil smoothly and directly down the ‘fall line’ and avoid bounces or pendulums that may draw the rope across an edge. Once at the next abseil position (or the base if on a sea cliff) secure yourself and the ‘bottom’ of the ropes to a new anchor point. It is helpful for the last person to abseil with a karabiner attached to whichever rope will be pulled, this will help separate the ropes prior to pulling them down. If it is a multi abseil descent the last person, having satisfied themselves that the main anchor is reliable, can remove the back-up anchor for use lower down.

Pulling through

Once the first climber has completed the abseil they should do a short test pull to ensure the rope will run properly. If it does not then the climber at the anchors should be able to identify the problem and rectify it. Once everyone is down carefully pull the correct rope. When pulling the ropes if possible take shelter from any rocks that might accidentally be dislodged.

Jammed rope

Despite precautions sometimes the rope will jam. If it does then try to flick it free or change the pulling angle. If after repeated attempts to free the rope it still will not move then someone will need to go back up and sort out the problem. If you still have both ends of the rope you will be able to either prussik up both ropes or climb up (tying into the rope at intervals to protect yourself). Do not prussik on a single rope as it could pull free at any moment with fatal consequences. If the rope has only partly pulled through leaving you with just one end it is better to climb back up with the rope you have. If there is no way you can climb back up you may have to cut the rope and continue as best you can.

Summary

  • Back up your anchors
  • Keep the rope clear of loose rock and sharp edges
  • Take precautions to avoid losing control or abseiling off the ends of the rope
  • Abseil smoothly
  • Do a test pull after the first climber completes the abseil
  • Keep self and ropes attached to anchor points

In addition to all the above those supervising abseils have a duty to consider potential risks inherent in the abseil and to take whatever measures are practicable to control those risks.

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