If two climbers need to rappel, whether on a single or multi-pitch route, and one of them is not able to rig his or her own rappels, then pre-rigging is a viable option.
1. Both climbers are attached to the anchor with slings girth-hitched to their harnesses.
2. The rope is threaded through the anchor as in the other systems.
3. The more experienced climber attaches his or her rappel device and autoblock backup as usual.
4. The other climber’s rappel is set up for him or her by the more experienced climber: A second sling is girth-hitched to the novice climber’s harness and attached with a locking carabiner to a rappel device that is prerigged on the rappel rope above the first climber’s device.
5. The experienced climber weights the rappel and engages his or her autoblock backup to hold him or herself in place. The other climber is still clipped to the anchor and ready to rappel.
6. The experienced climber tells the other climber that he or she will be given a fireman’s belay and can rappel as soon as he or she hears “on belay.” The experienced climber now rappels to the next anchor and clips in with a sling.
7. The experienced climber slackens the rappel rope and yells “on belay, rappel when ready” and immediately begins giving the other climber a fireman’s belay.
8. The other climber unclips his or her sling tie-in and begins rappelling. When the other climber reaches the belay, he or she clips into it with his or her anchor sling and goes off belay.
9. Both climbers now remove their belay devices, pull and thread the ropes through the new anchor and repeat steps 3 through 10 until they reach the ground.