When rappeling I understand the need for a backup--whether an autoblock below the belay device, or a second person providing a fireman belay. My understanding is that using an autoblock incorrectly can result in the autoblock rising up the rope to the point where it presses on and interferes with the belay device.

When this occurs would a fireman belay have any effect, or would the interference of the autoblock in the belay device prevent it from working?

  • ...and for the record: until I'm very comfortable/confident with an autoblock I'll only be using them in the gym while practicing, and using a fireman belay outdoors :)
    – STW
    Commented May 1, 2013 at 12:30
  • 2
    good question. I'd also repeat my advice yesterday, that if you're having continued questions about basic aspects of climbing (like rappelling safely), you should probably seek information from a formal source... a book, or maybe even a class. If you can afford it, a lot of guide services offer 2 or 3 day programs where a guide will spend a full weekend outdoors teaching trad climbing to a class of 1 or 2 students. You can have a genuine expert watch you closely for several days while you're actually climbing on real rock, teaching and correcting as you go. :)
    – DavidR
    Commented May 1, 2013 at 14:02
  • definately good advice that I intend to follow, although I trust my friends who take their lives into their own hands I don't necessarily trust their advice to take my life into my own hands :)
    – STW
    Commented May 1, 2013 at 15:02
  • yeah... there are a lot of bad, or at least sub-optimal, techniques that float around out there. Maybe some of them made more sense a generation ago when climbers used slightly different equipment. And you'll run into climbers who have been doing them for years, sometimes. That doesn't mean that there isn't a scenario where the outdated technique wouldn't cause a problem.
    – DavidR
    Commented May 1, 2013 at 15:11
  • If you're the first one rapping off, then you don't have the option of getting a fireman's belay. I guess the alternative would be to have someone lower you.
    – user2169
    Commented May 7, 2014 at 21:19

2 Answers 2


I think you understand this, but just for the record:

The recommendation is to learn how to use an autoblock correctly, and to make sure that the loops of the autoblock won't get caught in the belay device. This is done by a) extending the belay device, possibly with an anchor chain, and b) getting a custom made autoblock loop that is only long enough to wrap around the rope a few times, and too short to catch in the belay device. Avoiding getting the autoblock tangled is more a matter of assembling the right set of equipment in the first place than a specific motor skill.

As for whether or not a fireman's belay will overcome a stuck autoblock loop... probably, if the belayer pulls hard enough? I'd think it would. Its a little tricky to answer, because I don't think anyone has actually done rigorous testing on the dynamics of this system. I may be wrong.

  • so the safe answer would be that it could make the fireman's belay less effective. I'm thinking I'll be doing lots of learning on an autobelay in the gym until I'm sure I've got the autoblock down-pat
    – STW
    Commented May 1, 2013 at 15:05

I know I am answering a slightly different, more general question, but I think it is quite crucial to learn how to unjam a rappel device without relying on anybody else's help before embarking on any kind of outdoor-rappelling adventures.

I have gotten my ATC stuck more times than I'd like to admit. ATCs don't just like to eat poorly assembled autoblock loops, they also like to eat loose clothing, and long hair (ouch!).

So here I go:
If you are rappelling on a slab, a jammed ATC is often not that big of a deal. You can brace yourself against the slab and, while you are "walking up the wall," you pull yourself up with one hand, whilst taking in slack with your break hand: voila, your ATC is unjammed. This of course is not possible if you are hanging in mid-air, unless you are able to do one-armed pull-ups on a 9mm "string." In this scenario it is nice to have a cordelette with you. You can attach it to the ropes above the ATC with a prussic knot and step into the loop that is hanging down, effectively taking the weight off your rappel device. If you don't have a cordelette, use a sling or a second prussic (I always carry two, in case I have to ascend the rope) and clip a sling to it, or, if you don't have that, you can use some of the rope below your ATC, that you will have to knot up a bit.

The bottom line, and you got that as I can tell from your post: practice all this when you are hanging at a safe distant from the ground. With stuff like rappelling, belaying at a belay anchor, etc, I like to go through all scenarios I can think of: what happens if I drop this, what happens if I used up all of those, what can I do if my partner fell off the cliff or is unconscious and attached to me, what if I can only use one hand, what If I can't use either of my hands (now there it becomes interesting!), what if I can't see a thing, what if the rope has a knot, is damaged, whet, frozen or muddy, what if the two rope strands have different diameters, what if the anchor I am rappelling from can just barely hold body weight.

  • As someone who frequently answers a slightly more general question than was asked, I applaud this. So often, people recognize a critical situation, but ask exactly the wrong question about it. :)
    – DavidR
    Commented May 2, 2013 at 21:57

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