Crevasse Rescue Techniques Every Mountaineer Should Know
A crevasse fall on a roped glacier is one of the most sudden and disorientating emergencies in mountaineering. The snow bridge collapses without warning; the climber drops; the rope snaps tight. The situation is immediately serious — the fallen climber may be suspended in a slot of compressed ice, unable to self-rescue, and cold air pooling in the crevasse will lower body temperature within minutes. The effectiveness of the response in the first five minutes, while the fallen climber is still warm, has fingers that can grip, and energy to assist, determines the outcome.
Crevasse rescue is not an advanced mountaineering skill. It is a baseline competency for anyone who travels on roped teams on glaciated terrain — the same category of skill as basic first aid or navigation. It does not require great strength if the technique is correct; mechanical advantage provided by improvised pulley systems means a single rescuer can haul a fallen teammate up and out of a crevasse. But it requires prior practice and understanding; improvising the system from scratch while managing the stress of an emergency on a cold glacier is not the moment to figure out how prussik loops work.
Immediate Arrest
The sequence begins before rescue: with preventing the fall from becoming a free fall. A rope team travelling with correct spacing and attentiveness should be able to arrest a crevasse fall as soon as the rope loads. The non-falling team members must react immediately — dropping the body weight forward and down onto the snow, driving the ice axe pick into the ice, and braking with the rope across the shoulder or through a hip belay. On hard, compressed snow, this arrest is straightforward. On soft, fresh snow, the arresting climber may slide before getting the axe planted — which is why ice axes must be carried at the ready, in hand, on crevassed terrain, not stowed on the pack.
Once the fall is arrested, the arresting climber is in a loaded position with the rope under tension. Releasing the rope to transition to hauling is the first technical challenge. The fallen climber must be secured — their weight transferred from the arresting climber's body to an anchor — before any hauling system can be set up.
Building an Anchor
The standard snow anchor for crevasse rescue is the deadman, also called a snow picket or buried-axe anchor. To build a buried axe anchor: bury the ice axe horizontally in the snow at 90 degrees to the direction of pull, with the rope attached to the shaft at its midpoint by a sling. The axe is buried at 45 degrees forward into the slope, angled so that the load tends to press it deeper rather than pull it out. Pack snow firmly over the axe and stand on it.
If the rope runs over the edge of the crevasse into the slot, the edge must be padded before hauling begins. The rope under load cuts into a snow lip, increasing friction enormously and potentially burying the rope so deeply that hauling becomes impossible. A pack, a crampon, a tent pole, or any flat object slid under the rope at the edge reduces this friction dramatically.
Prussik-Assisted Self-Rescue
The fallen climber, if conscious and unhurt, can assist or conduct their own rescue. Prussik loops — short loops of thinner cord tied with a prussik knot around the main rope — grip under load and release when unweighted, functioning as one-way cam devices. The climber carries two prussik loops on their harness. In the crevasse, they clip both prussiks to the rope: one as a foot loop, one clipped to the harness belay loop. Alternating body weight between foot loop and harness loop, they climb the rope hand-over-hand, advancing each prussik upward when unweighted.
Prussik climbing is more tiring than it sounds and becomes progressively harder as the climber's arms and legs exhaust. The lip of the crevasse presents a particular challenge: the rope cuts into the lip, and climbing over an overhanging snow edge while suspended on prussiks and wearing crampons and a pack is physically demanding. Removing the pack and hauling it separately, or having the surface team pull from above, reduces this difficulty substantially.
The Z-Pulley System
For rescue from the surface, the Z-pulley (or Z-drag) provides a 3:1 mechanical advantage, meaning the rescuer applies one unit of force but the system delivers three to the rope. The system uses prussik loops on the rope to function as progress-capture devices (ratchets that prevent the system from slipping backward while the rescuer repositions their grip).
Setting up the Z-pulley: First, secure the anchor and transfer the fallen climber's weight to it. Then clip a carabiner to the anchor. Run the main rope from the crevasse up to the anchor carabiner and back out to a second carabiner on a prussik loop clamped to the main rope — this forms the Z shape. Pull on the end of the rope running from the second carabiner back toward the crevasse. A third prussik loop, clamped to the main rope between the anchor and the first carabiner and connected back to the anchor, acts as a progress-capture device, preventing the rope from running back.
The Z-pulley requires only one rescuer in theory. In practice, a second rescuer to tend the fallen climber as they emerge over the lip — guiding the rope, assisting the climber over the edge, and providing communication — greatly improves the outcome.
Communication and the Importance of Practice
Verbal communication with the fallen climber is critical throughout. Knowing whether they are injured, whether they can assist, what depth they are at, and whether the hauling is working or the rope is snagging allows the surface rescuers to adapt their approach. Standard signals — pulls on the rope, shouted codes — should be agreed before the team enters crevassed terrain.
The single most effective preparation for crevasse rescue is practising on a safe slope before the actual glacier. The glacier map shows which glaciated areas involve significant crevasse hazard and which are primarily snow-covered lower-angle terrain. Most guided glacier programmes include a short rescue demonstration; taking a dedicated glacier skills course that includes live crevasse practice — being lowered into a slot and hauling yourself or a companion out — provides the muscle memory that makes the real-emergency version far more manageable.