Is rope-soloing inherently dangerous, and if so, why?

Question

I've never tried rope-soloing and don't have a very detailed idea of how it's done. But reading the 2015 edition of Accidents in North American Mountaineering, I was struck by how many accidents happened to people who were rope-soloing. My impression is that only a very small percentage of climbing is done using this technique, so the number of accidents would be disproportionate, suggesting that it's either an inherently dangerous activity or maybe one that a lot of people do incorrectly. On the other hand, it seems like a technique that could be useful for self-rescue, for example if your partner gets hurt.

Why does rope-soloing seem to be so dangerous?

Related:

Technique for lead solo climbing with rope

Most common avoidable reasons for climbing accidents?

Answer 1

I do not have knowledge about the particular accidents stated in the question, so my answer is directed at rope soloing in general.

The fact that more reported accidents happen when rope soloing is moste due to the fact that it is soloing. While in a team many minor accidents can be handled by yourself, so there is a huge number of accidents that do not need rescue and therefore never get reported. When soloing you are almost certainly stuck when anything happens, so you will need assistance. Therefore the number of unreported accidents is much smaller.

The second factor is the higher complexity in the system. You have more and complicated gear to handle (just read the question linked, there may even be stuff like modified grigris involved). The amount of errors made always scales with the complexity of the system. Even in the less complex system of climbing in a team, it is highly recommended to do partner checks at all time to introduce redundancy and thus find errors. Because knowledge and experience does not prevent errors (some studies even state the contrary effect, i.e. habituation increases the chance of errors), the fact (true?) that only well trained people do rope soloing does not help either. Again in rope soloing you do not have a partner with a second set of hands, eyes and another brain to check what you are doing. And I am not ashamed to admit that this second brain potentially saved my ass several times in the mountains.

Answer 2

I would like to add several more factors to generally excellent answer by @imsodin. These reasons are perhaps more technical and assume passing familiarity with rope solo techniques. There are obviously ways to mitigate many of these issues, but this is beyond the scope of the question and the philosophical distinctions remain.

• Off label usage: With the exception of a handful of discontinued (and consequently very expensive) devices, rope soloists are using equipment from the climbing and industrial rope access worlds in ways for which they were never designed nor certified. This leads to backyard science, forum discussions, and modifying equipment, rather than certifications from governing bodies and industry approved best practices taught by qualified instructors. Additionally, many devices from the industrial rope access world (which might otherwise be useful) are incredibly heavy and stupendously expensive. As it stands, rope soloing involves needing to deeply understand the flaws and limitations of these off-label usages and either accepting or (attempting to) mitigate them.

• Clunky: Rope solo systems are generally a design trade-off between ease-of-use/unhindered climbing vs. security/redundancy. For a simple example, it is considered best practice to be connected to backup knots in the rope in case of main device failure. However, managing numerous backup knots in the rope is quite cumbersome and thus these backup knots are generally spaced quite far apart, resulting in long falls should the main device fail. Other rope soloists will only tie backup knots in the rope without being connected to them, relying on these knots getting jammed in their main device to arrest a fall. Yet others forgo backup knots entirely. For another example, rope solo falls can cross load and break carabiners. Hence the use of ANSI-rated carabiners, steel carabiners, or even steel mallions/screwlinks/quicklinks for critical connections is a way to increase safety. However, these options are heavy, more difficult to use, and potentially expensive (especially in comparison to the trusty locker from your climbing rack).

• Hindered climbing: Especially in the mountains and on runout climbs, a large amount of a climber's safety comes from simply not falling in no-fall zones. However, no rope solo system yet devised comes anywhere near smoothness of an attentive belayer. Every rope soloist has had the experience of having a device lockup, a backup knot come tight, or a rope tangle while in the middle of a hard clip or desperate runout crux move. Lead rope soloing can sometimes feel like trying to lead an R-rated climb with a novice belayer who has never used a Gri-Gri before while the rope is a tangled mess. Put another way, getting short-roped while sport climbing is frustrating, but is quickly rectified with even a mediocre belayer. Short-roping yourself while rope soloing can require downclimbing to somewhere you can get both hands free to deal with unlocking your device / undoing backup knots / dealing with rope tangles. For these reasons, lead rope soloing a pitch generally feels about a full number grade or aid grade more difficult than it would with a competent belayer.

• The rope is fixed: In normal climbing, the belayer (and belay device) is stationary while the rope moves upwards with the climber. In rope soloing, one end of the rope is fixed at the anchor while the belay device moves upwards with the climber. This change can result in some subtle and pernicious issues that are unique to rope soloing in the climbing experience. For example:

  • Backfeeding. Once high enough on a pitch, the weight of the rope between the anchor and the climber can cause the climber's free rope to start backfeeding through their belay device, resulting in suddenly having 5/10/30/60m of extra slack. This is incredibly dangerous and has to be prevented (adding yet more clunky hindrances to the system).
  • Nobody is at the anchor. In a normal climbing scenario, the belayer is at the anchor keeping an eye on things, making sure carabiners aren't cross-loaded, cams haven't shifted, and so forth. Not so for rope soloing.
  • Higher forces. Because one end of the rope is tied directly to the anchor, taking a fall while rope soloing results in a very hard catch. In contrast, some of the peak forces in a climbing fall are absorbed by pulling the belayer upwards. Additionally, a belayer (and their belay device and carabiners!) see a fraction of the forces of the leader due to friction. However, rope soloing relocates the belay device (and carabiners) up to the leader, where they will generally experience higher forces.
  • Rope wear. While rope soloing, every fall causes the same section of rope to get rubbed against the same sharp piece of rock. In contrast, a normal climbing scenario sees the rope move upwards with the leader, causing rope wear to be distributed along the length of the rope instead of concentrated in a single spot.

• The belay device is moving: In a normal climbing scenario, the belayer is managing the belay device: making sure carabiners aren't cross-loaded, the rope is feeding smoothly, the belay device isn't tangled with other climbing equipment, and so forth. When rope soloing, the device is moving up the rope with the climber getting banged against rocks, tangled with climbing equipment, tangled with loops of rope from backup knots, slings getting sucked into the device, getting cross-loaded in falls, and getting grabbed at by a panicked soloist in a fall. The belay device is thus put into a more dynamic environment with more variables at play and ways for it to fail.

While many of these listed factors aren't necessarily dangerous in isolation per se, they are all problems that must be dealt with while alone on the side of a cliff. Additionally, attempts to solve or mitigate these problems generally increase the complexity of the system, adding more points of failure and more potential errors. Finally, these are just the added dangers of rope soloing (especially lead rope soloing)---there are still all the usual dangers of climbing as well.