Self-arrest is a mountaineering related maneuver in which a climber who has fallen and is sliding down a snow or ice slope arrests (stops) the slide by himself or herself without recourse to a rope or other belay system.
Self-arrest can be performed by using an ice axe and/or by using a climber's crampons, boots, hands, feet, knees and elbows. Self-arrest with an ice axe can a difficult maneuver, but without this piece of mountaineering equipment the probability of effectively stopping a fall is greatly diminished.
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This article is not intended to provide instruction on how to perform a successful self-arrest. Its scope is merely descriptive in nature. Do not expect to be successful performing a self-arrest just by following the description in this article. Self-arrest should be learned from a qualified instructor and requires repeated actual practice in order to become proficient at it.
With an ice axe:
The most important part of the maneuver is to get into self-arrest position. In this position the climber is face down with feet oriented towards the valley, arms tucked in, one of the hands on top of the ice axe the other down the shaft. The top of the axe is against the shoulder or its vicinity and the pick of the ice axe in contact with the slope. Once in this position the climber arcs his body, so that it contacts the slope mainly in three points, the pick and his feet or knees, in order to bring as much of his weight to bear on the pick as possible.
This is easier when the climber falls face down and is sliding feet first towards the valley. If he falls in any other position, face up, feet toward the slope, etc., he must first orient his body in the optimal position by twisting his body and using the pick of the ice axe as a pivot point. In these cases the maneuver may be much more difficult to perform.
Without an ice axe:
Without recourse to an ice axe, the climber should try to orient the body face-down, feet towards the valley, and to put, by arcing the body, as much pressure as possible in the hands and feet, or knees.
While wearing crampons:
In both cases a climber wearing crampons should put the feet up and use the knees instead. Putting weight on the feet while wearing crampons will cause their points to snag in the ice or snow, causing injury to the climber's ankles and sending him/her tumbling down the slope without control.
To be able to perform the self-arrest maneuver the pick of the ice axe should stick outwards when the hand on top of it is brought to the shoulder. To guarantee that this is accomplished as fast as possible, climbers often adopt the so-called self-arrest grip. In this grip the axe is held in the hand with the pick looking backwards, adze looking towards the direction of travel. If the axe is being held pick forward, it needs to be reversed in the hand to bring it to bear against the slope. This makes the maneuver slower and can cause the climber to lose control of his ice axe.
Effectiveness of self-arrest
Self-arrest is by no means an infallible technique. The chances of being able to arrest a slide in this way are estimated by reputable sources to be around 50% and they vary as a function of three factors:
- Angle of the slope: The higher the angle of the slope the harder to arrest a slide. Above certain angles the chances may be very close to nil.
- Hardness of the slope: The harder the surface of the slope the harder it is to perform self-arrest. On icy slopes, the pick may fail to engage the surface, or it may bounce with great force on hitting a snag making it difficult to even maintain control of the axe. Negative or neutral angle points are considered superior by some in this regard as they have a lower tendency to snag in the hard ice while others maintain that they will not penetrate ice as easily as positive angle points.
The tip of the pick of the ice axe forms a short blade. When there is positive clearance the downhill point of this blade will engage the ice first when the axe is in arrest position. With negative clearance the uphill point of the blade will engage first. On hard ice, a negative-clearance-axe will skate across the surface when attempting arrest, resulting in very little braking force. This has often resulted in very serious injury and death. A positive- clearance point will dig in aggressively, requiring skill to avoid excessive braking force but giving the climber his/her best chance to survive.
- Speed in performing the maneuvre: The longer the delay of the climber before he/she starts to put weight on the axe's pick the longer s/he freely accelerates down the slope. If the climber is slow to perform the maneuver, by the time s/he gets in self-arrest position his/her speed may be high enough to make the arrest impossible. Due to this phenomenon, all climbers should at all times maintain the utmost proficiency in their self-arrest skills. Many climbers would wisely dedicate a day at the beginning of the season to reviewing self-arrest techniques in order to maintain their proficiency over time. The maneuver should be practiced in all its possible variants.
Self-arrest as a security measure
Self-arrest is a measure of last recourse. In general one should not rely on self-arrest to guarantee security while engaging a slope. Instead the appropriate techniques of self belay or roped belay should be used. Security experts have suggested that sole use of the rope without intermediate protection points, as done by roped parties during glacier travel, should be avoided in slopes. This technique may make self-arrest almost impossible, causing the fall of a single climber to bring down the entire party.
- Pit Schubert, Sicherheit und Risiko in Fels und Eis Band 1 (7th edition), Bergverlag Rother (2005), ISBN 3-7633-6016-6