SRT kit - deadly accident in Switzerland

[cap n chris]

The 2013 Petzl Basic solves it anyway.

 

[Burt]

Anyone use a twistlock?

I use twistlocks on via ferrata but not SRT (screwgates). The convenience of twistlocks is great but they don't perform properly when full of mud.

 

[cavermark]

The 2013 Petzl Basic solves it anyway.

...if the cowstail is clipped direct to the ascender (the new basic has a lrge enough hole for 2 krabs)

 

[cap n chris]

(the new basic has a lrge enough hole for 2 krabs)

Indeed, which is why I posted....

The 2013 Petzl Basic solves it anyway.

 

[Mike Hopley]

Chris has it right, and that video is useful. I hadn't seen this method of failure before.

It's worth reiterating that the "double carabiner" setup is not a peculiarity of Alpine Caving Techniques. It's a very common European setup, and it's recommended by the French Caving School in their 2013 technical guide. If anything, we in the UK are the oddballs, with our unusual tied-in safety cords!

Here's what they say about cowstail carabiners:

Cavers use two cowstails for moving along ropes ... The karabiners are snap-gate D-shapes ... Avoid bent- or wire-gate karabiners as they have a tendency to open unexpectedly.

And here's what they say about the jammer safety (i.e. long cowstail -- they don't even consider our UK method):

For cavers who do not want to have the upper jammer permanently connected to the long cowstail, it can be connected directly to the foot loop instead and the cowstail connected indirectly via the foot loop karabiner. If you do this, it is important to use a screwgate karabiner with a breaking strength in excess of 22kN, as it will have the cowstail karabiner connected to it.

Either setup is fine, providing it's used correctly. Chris's video, however, suggests that a "double snapgate" setup is not safe. This is useful to know, and it's consistent with the EFS recommendation.

 

[glyders]

Anyone use a twistlock?

Not a twistlock but a self-locking krab - the ones from a via ferrata rig. They do jam up a bit now after a lot of muddy abuse, but still close quicker than a screw gate. They also have a nice big open and with a conveniently small rope end.

As a climber I have managed to have a wire snap gate come off a nut. Doesn't stop me using them though, just being aware of the potential problem. I don't find the need for them in caving though.

 

[Mike Hopley]

Not a twistlock but a self-locking krab - the ones from a via ferrata rig.

I used to use those on my cowstails (this one) Excellent krabs -- about as fluid as a snapgate.

The main downside is weight -- about 125 grams instead of 40, which makes the hand jammer feel noticeably heavier when prusiking.

For a non-French long cowstail, though, I think they're pretty good.

 

[glyders]

Not a twistlock but a self-locking krab - the ones from a via ferrata rig.

This is the kind I meant. No real difference in weight to an HMS. Yours look pretty funky though.

 

[Griffin]

Out of interest, I use an older version of these:

http://dmmprofessional.com/products/captive-eye-kwiklock-a913/

I got my srt kit with snap gates on cows tails 2 years ago (I bought the caving supplies complete kit). But never really liked them, and switched to these twist locks last year which have been pretty good for me so far. I have used them in some very muddy places, the twist locks just needs a thorough clean after each trip. The only downside is the big notch on the nose which tends to snag on rope but I am not sure is the same on these newer models- what exactly is a taperlock clean nose? And also, some cavers have made fun of my silly big carabiners! 

 

[Mike Hopley]

what exactly is a taperlock clean nose?

"Clean nose" normally means "no hooky bit to snag rope".

DMM/Google say:

We?ve given it a Taper Lock nose, a special flared profile on the nose of the biner which significantly increases the side loading strength of the gate.

And also, some cavers have made fun of my silly big carabiners! 

Tell them the ladiiieesss like a big carabiner.

With a taperlock clean nose -- a special flared profile...

 

[Mike Hopley]

Back on topic:

I looked more carefully at the Swiss report, using a combination of Google Translate and my schoolboy French (not my French schoolboy, who remains locked in the cellar).

They come to the same conclusion Chris did: the accident probably occurred because, as the victim stood up in her footloop, the footloop/carabiner/jammer assembly was under tension, whereas the long cowstail was slack and its carabiner was free to move around. As she sat back down, the long cowstail carabiner levered open the footloop carabiner, thereby unclipping itself.

I think they also say that the specific carabiner she used had a weak gate spring, which exacerbated an already unfavourable situation.

They recommend that the cowstail should be directly connected to the jammer if possible. They say that, even without a locking carabiner, this is a very secure arrangement; and by using a locking carabiner, the last shred of doubt can be eliminated.

If this is not possible (e.g. with the pre-2013 Petzl Basic), they recommend using a locking carabiner (or maillon) to hold the footloop. The gate must be locked! They say that the footloop carabiner should be oriented with the gate opening at the top.

This last recommendation is interesting. Presumably the point is that, if the gate should accidentally unlock, the carabiner is oriented so that accidental unclipping is much less likely.

Previously I would teach people to orient the carabiner with the opening downwards, so that gravity tended to close the gate rather than open it. Now I think I'll have to change that.

 

[Griffin]

Haha I am a lady!!! 

 

[Mike Hopley]

Haha I am a lady!!! 

I'm sure my bad joke could be repurposed accordingly.

 

[ianball11]

...they recommend using a locking carabiner (or maillon) to hold the footloop. The gate must be locked! They say that the footloop carabiner should be oriented with the gate opening at the top.

This last recommendation is interesting. Presumably the point is that, if the gate should accidentally unlock, the carabiner is oriented so that accidental unclipping is much less likely.

Previously I would teach people to orient the carabiner with the opening downwards, so that gravity tended to close the gate rather than open it. Now I think I'll have to change that.

Interesting

 

[Bottlebank]

Thinking on on this, the advice always used to be never consider one jammer to be sufficient security. Something I've stuck with over the years without really thinking about it. Good advice, looking at this example. Hindsight is like that.

 

[Fulk]

Quote from Mike Hopley:

They come to the same conclusion Chris did: the accident probably occurred because, as the victim stood up in her footloop, the footloop/carabiner/jammer assembly was under tension, whereas the long cowstail was slack and its carabiner was free to move around. As she sat back down, the long cowstail carabiner levered open the footloop carabiner, thereby unclipping itself.

Sorry, I don't 'get' it; would it be possible to post a diagram of what you think happened? Thanks.

 

[Mike Hopley]

Okay, here are some photos that might clarify things.

First, let's look at the victim's SRT setup (this is my kit, not hers). The hand jammer is connected to a snapgate carabiner that holds the footloops. For security, the long cowstail is connected to the footloop carabiner:



The hazard occurs because of the double-snapgate carabiner chain. The hazard can be prevented by using several different setups. The pictures below show, in order:

[list type=decimal]
[*]Clipping the long cowstail directly into the jammer, if the jammer design allows it;
[*]Using a locking carabiner for the footloops, with the gate closed, and the carabiner preferably oriented with the opening at the top. A screwgate may be preferable to a twist-lock in this context;
[*]Tying in directly to the footloop carabiner (UK style). A snapgate is then acceptable, although a screwgate may be preferred.
[/list]



All these different setups are considered safe. The victim's setup is considered dangerous because the long cowstail can unclip itself. This can happen when standing up in the footloop. The cowstail can move around, and may be raised accidentally by the victim wrapping it around a hand, or otherwise catching it on something.

When the caver sits down, the cowstail becomes weighted. During this process, it may catch on the footloop carabiner, which it can then open in a twisting motion.

The photos below illustrate how this can happen. Note that the footloop carabiner is oriented with the opening at the bottom, which makes unclipping much easier.

I have moved the camera around (between photo 2 and 3) to get a better angle. This makes it look like the jammer is getting twisted on the rope, but it's not.

 

[Tangent_tracker]

So the moral of this story is, quite simply, NEVER clip a crab (regardless of locking or not) into a snap-gate!!!!

So sad that this caver should have died through something so 'silly' and yet not immediately obvious!

 

[Fulk]

Thanks for that Mike . . . the moral I'd draw is 'stick the the "UK style" with a separate long cow's  tail'.

 

[Mike Hopley]

I also made a video showing the unclipping action.

http://youtu.be/QVkdCItK6oo

The moral I would draw is:

[list type=decimal]
[*]Avoid clipping a snapgate into another snapgate.
[*]Be extremely careful whenever you are attached by just one thing, especially if that thing is unweighted.
[/list]

So sad that this caver should have died through something so 'silly' and yet not immediately obvious!

Yes. It initially appears to be a reasonable modification -- "given that you're already using one snapgate, how could another make you less secure?" -- but in fact there is an unexpected hazard.