Rappelling

An abseil (/ˈæbseɪl/ or /ˈɑːpzaɪl/; from German abseilen, meaning "to rope down"), also called a rappel after its French name, is a controlled descent of a vertical drop, such as a rock face, using a rope.

Climbers use this technique when a cliff or slope is too steep and/or dangerous to descend without protection. Many climbers use this technique to protect established anchors from damage. Rope access technicians also use this as a method to access difficult-to-reach areas from above for various industrial applications like maintenance, construction, inspection and welding. Rescue teams are also known for using this method as a way to access injured or stranded victims.

The origin of the abseil is attributed to Jean Charlet-Straton, a Chamonix guide who lived from 1840–1925. Charlet originally devised the technique of the abseil method of roping down during a failed solo attempt of Petit Dru in 1876. After many attempts, some of them solo, he managed to reach the summit of the Petit Dru in 1879 in the company of two other Chamonix guides, Prosper Payot and Frédéric Folliguet, whom he hired. During that ascent, Charlet perfected the abseil.

Abseiling is used in a number of applications, including:

Abseiling can be dangerous, and presents risks, especially to unsupervised or inexperienced abseilers. According to German mountaineer Pit Schubert, about 25% of climbing deaths occur during abseiling, most commonly due to failing anchors. Another frequent cause of accidents is abseiling beyond the end of the rope. Backing up the rope set-up with a friction knot (autoblock, Kleimheist, or prusik) such that the slipping of the rope is stopped even if the climber lets go of the control rope provides a measure of safety with regard to the control of the rate of descent.

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Wikipedia