The person on the surface, the "rescuer", must always be anchored. If creating a second anchor is not possible, the rescuer can use the same anchor as the victim. The rescuer's movements must be done with the rope under tension to avoid a shock load in case of a fall, which could weaken the anchor.

Moving with an autoblock knot on the victim's rope

If the "rescuer side" of the rope is too short, it is possible to move with the autoblock on the taut rope supporting the victim. The rescuer must tie-in again as soon as possible after returning to the anchor.

Warning: in this case, if the rescuer falls, for example if the crevasse lip collapses, both climbers will be held by the same rope. The stresses on the system will be significant (anchor + progress capture pulley).

• The anchor could fail, causing both climbers to fall.
• If the anchor holds, the rope could be damaged or cut by the MICRO TRAXION's cam, especially if the rope is thin (See test results at the end of this document).

Moving with an autoblock knot on the rescuer's rope

The autoblock allows the length of the rescuer's belay rope to be constantly adjusted, without needing to untie from the rope.

Author and source

This Petzl technical documentation is shared on https://www.camptocamp.org in partnership with the Fondation Petzl. Petzl Foundation aims to conduct educational and risk prevention actions related to the practice of vertical activities. This documentation is available under the Creative Commons CC-by-nc-nd licence.

Author: Petzl
Source: petzl.com
Version: V1
Date: 26/01/2015