I touch briefly on this consideration in the free article: Redundancy in Rope Systems. Backup BelayerĪ common and valid criticism with having a single operator controlling both lowering devices is that THAT person is a single point of failure in the system.

In the RopeLab member report Members: Matching Tension with Mirrored Systems, I discuss the effectiveness of using two Petzl IDs operated by a single operator and found that, even with attempts to mismatch, the tensions never deviated outside 60/40 – 40/60. It is common to observe big swings from 90/10 to 10/90 between the two as the operators attempt to match each other’s rate of lower. Systems like the one shown above, while functional, make it very difficult to match the tension in the two ropes. Matching Tension Dual main system using CMC Rescue MPDs for lowering Instead I would like to focus on the implementation of dual main lowering systems for rope rescue operations. Much has been written by others about the relative merits of each of these systems and I will not discuss them further here. Dual main implies that our two rope system sees both ropes loaded and capable of task completion should one of these ropes ‘disappear’. I am deliberately choosing to stick with the simplest of terms here and ‘ dual main‘ covers all bases.

Single main/single backup systems normally see the task undertaken using a main rope with another backup rope on standby should the main fail. There is a growing awareness of the benefits of dual main over the more traditional single main/single backup rope systems.

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