[1] Crevasse rescue is considered a core skill set in alpine climbing, but difficult to do efficiently.
Even if the fallen climber is largely unharmed with no broken limbs, the narrow walls of the crevasse are very cold and hypothermia can develop quickly.
[5][6] If the fallen climber can move and has prussik knots and/or ascenders, then they can jumar up the now fixed rope and effectively perform a self-rescue to the surface.
[2] For smaller teams, the other climber(s) may try to set up a pulley system using prussik knots, snow anchors, and climbing pulleys, to reduce the hauling effort, and ideally, a Z-pulley system that will give them a 3:1 mechanical advantage,[2] however, there are many variations depending on the specific equipment and skill-level of the members.
[8] In very developed areas, such as the Mont Blanc Massif, rescue helicopters have mechanical winches to directly haul climbers — or skiers — from deep crevasses.