SRT kit - deadly accident in Switzerland

[Roger W]

Well explained, Mike.  That makes it very clear.

 

[Mike Hopley]

I was rushing out and made an error:

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]

Correction:

[list type=decimal]
[*]Avoid clipping into a snapgate, especially if it's weighted (in this case, weighted by the footloop).
[*]Be extremely careful whenever you are attached by just one thing, especially if that thing is unweighted.
[/list]

 

[idriswilliams]

Hi,

It seems to me that the concentration on the snap link issue hides the main issue.

There was only one point of attachment and it failed. If there had been two the chances of both failing simultaneously are infinitesimal. It also seems to me that it shows the system of using the long cowstail as a foot jammer safety means that a long cows tail may not be available at a pitch head or rebelay and if the rigging does not allow the easy attachment of the short cowstail then the caver is at risk. The system that most of us use (in the UK) with a separate dynamic safety cord to the foot jammer gives us a cowstail that is free in this situation.
I personally use snaplinks on my cowstails and teach that to others. However, I always preach (and practise) two pionts of attachment and that the snap links are clipped so that the opening is visible. Whilst progressing on a traverse one of these could be a "firm stance" on a ledge. If this is not possible the safety cord and it's KARANIBER can be used as a back up while moving the cowstails on.

We can argue for ever on the snaplink/twistlock/karabiner issue and there are good points on each side, but if the is only one point of attachment trouble seems likely.

Idris Williams

 

[Mike Hopley]

It also seems to me that it shows the system of using the long cowstail as a foot jammer safety means that a long cows tail may not be available at a pitch head or rebelay and if the rigging does not allow the easy attachment of the short cowstail then the caver is at risk.

In this unlikely event, you just swap cowstails. Now the short cowstail is on your jammer, and the long cowstail is available.

I've almost never had to do this, though.

The system that most of us use (in the UK) with a separate dynamic safety cord to the foot jammer gives us a cowstail that is free in this situation.

Yes, and that is an advantage of the UK system (or any system with three cowstails).

This can seem like an overwhelming advantage if you were taught in the UK. But it really depends what you're used to! The French (and other Europeans) have been practising SRT safely for a long time.

An occasional accident does not invalidate their approach, especially when the victim was using equipment and techniques (see below) that are specifically forbidden in French instruction.

We can argue for ever on the snaplink/twistlock/karabiner issue and there are good points on each side, but if the is only one point of attachment trouble seems likely.

The French approach inherently relies on a single point of attachment in specific circumstances. When practised correctly, this is no more dangerous than using a single point of attachment for abseiling.

(...abseiling is probably the most dangerous part of SRT, but that's another topic.)

So far the discussion has focused on the equipment of the victim, which was configured incorrectly. Maybe we should think about the victim's technique too.

When using a jammer for security on a traverse, the long cowstail should be clipped around the rope too -- i.e. the cowstail is clipped into the jammer and the rope. This ensures the jammer will be loaded correctly in a fall (otherwise it may detach, or at least slide).

We can't know for sure what technique the victim used during her fatal traverse. But the accident report does include a photo from the previous day, which shows her long cowstail is not clipped to the rope.

So it is likely that the victim made a technique error, in addition to her error configuring the equipment.

If she had clipped the long cowstail into the rope, it would probably have saved her. It is very unlikely that the cowstail would unclip itself from the rope at the same instant as unclipping itself from the footloop carabiner.

You could argue she made a second technique error too. When she failed to reach the next section with her short cowstail, she should have immediately reconnected it, rather than sitting down onto her jammer.

 

[Alex]

We can argue for ever on the snaplink/twistlock/karabiner issue and there are good points on each side, but if the is only one point of attachment trouble seems likely.

But correct me if I am wrong but even on our system when traversing for example you are quite often on one point of attachment although for a short time, i.e. as you go onto the next piece of rope beyond a knot. You take one of your cows tails off the rope (so now you only have one attached) and place it onto the next. Do you use a 3rd cows tail to avoid this, maybe unscrew your hand jammer?

 

[Fulk]

Alex:

But correct me if I am wrong but even on our system when traversing for example you are quite often on one point of attachment although for a short time, i.e. as you go onto the next piece of rope beyond a knot.

For me, it depends on the situation; if it's an easy traverse, I'm quite happy to be on one point of attachment . . . on a difficult traverse I'd still be on one cow's tail, but I'd make sure that the krab was screwed up.

 

[Bottlebank]

But correct me if I am wrong but even on our system when traversing for example you are quite often on one point of attachment although for a short time, i.e. as you go onto the next piece of rope beyond a knot.

Not really, most people would normally also have hold of the knot with their spare hand.

 

[Mike Hopley]

Not really, most people would normally also have hold of the knot with their spare hand.

That's not normally considered a "point of attachment" though.

Alex: the short answer is "you're right". It's normal to have only one point of attachment when passing intermediate anchors on a traverse line. In theory you could attach a third cowstail or a jammer at this point, but I don't think I've ever seen anyone do that.

It's even common to move along a traverse with just the long cowstail attached, as this gives freedom of movement.

 

[Bottlebank]

"That's not normally considered a "point of attachment" though."

It is in my book The point is to have two points of attachment whenever practical, and especially when totally reliant on your gear. A traverse is a slightly different situation as to progress you need to move your attachment points, using a hand jammer isn't a great idea, people tend to forget they have two perfectly good limbs!

 

[Blakethwaite]

Granted a normal person might be able to halt a slide with one hand but I wouldn't like to say I could hold a proper fall if my cowstail failed!

Your arms aren't a point of attachment, not this far east of Hollywood anyhows!

 

[Bottlebank]

My point was your arm is simply providing a second point of attachment when you change over your cowstail on the traverse, you still have the second cowstail attached.

 

[caving_fox]

Alex: the short answer is "you're right". It's normal to have only one point of attachment when passing intermediate anchors on a traverse line. In theory you could attach a third cowstail or a jammer at this point, but I don't think I've ever seen anyone do that.

I do. I have a third (very short) cow's tail for just this purpose, and for rigging when it's useful for being held close to the wall for a while.

IN general if it's a 'normal' traverse I don't bother with it, but when it's a bit airy, I will often clip my very short in, transfer the other two across one at a time, and then move on. I'm tall with long arms, and so have quite a long 'long' and a 'short' that is about as long as some people's 'long'. It is useful to me to be able to sit closer to the wall at such times.

Note also for technical pedants. Most people's cow's tails are formed from one piece of rope. Hence are only 1 point of attachment anyway if the knot at the D ring fails.

Again personal choice, I bear the extra weight and clutter for a bit more convenience.

 

[Bob Mehew]

"That's not normally considered a "point of attachment" though."

It is in my book

You are assuming your hand can retain its hold of the rope / knot during the fall which is a big if.  Also I recall that following the fall, the blood supply to a hand is then reduced because of its clenched state.  So the grip will be lost within tens of seconds as the finger muscles loose their capabilities due to lack of fresh blood.  So how long can you hang onto a rope / knot?

 

[Rhinolophus]

Finger strength comes from the forearm muscle not the fingers themselves they are just made up of tendons and pulleys having a clenched fist wouldnt stop bloodflow to the forearm!

 

[potholer]

Personally, I don't typically feel especially exposed in the pretty rare situations where I can only move (or move easily) with a single long cowstail on a high traverse line, as long as it's possible to make some other attachment at knots while transferring the long cowstail.
I might do up the little-used screwgate on my long in such a situation, though possibly to a large extent for psychological reasons.
If the knots were high as well as the inter-knot rope and I had to do something unusual to make a safe transfer, like using a sling+krab or my safety cord to make a second long cowstail, I guess I'd leave that attachment on as well, but at least partly for convenience as well as redundancy - there seems no point having a temporary connection active only during transfer if that's actually more effort in terms of manoeuvres+tidying kit away between uses than having the second connection almost always connected.

I'd tend to see 'always use two cowstails' to be less justified by a particular need for gear redundancy in case of slipping while moving than to avoid the situation of someone who typically used one cowstail briefly going from one to no connections during a transfer due to recklessness or fatigue - two being a good idea not so much because one was particularly bad, but because zero was very bad.

 

[Mike Hopley]

two being a good idea not so much because one was particularly bad, but because zero was very bad.

Exactly. A good way to think about it.

Most people's cow's tails are formed from one piece of rope. Hence are only 1 point of attachment anyway if the knot at the D ring fails.

But that's not a realistic scenario, unless you let your cowstails get really badly worn (i.e. the core is showing).

After all, we're rigging pitches with one piece of rope. Our harnesses have one D-ring, and one webbing/metal loop for closure on each side. The descender is one item. Failure of any one of these items would typically be fatal.

So really, the concept of "point of attachment" is a bit fuzzy. It's more useful to think about the whole safety chain: anchors > slings/connectors > knots > SRT rope > cowstail krab/jammer/descender > connection to D-ring > D-ring > harness > caver. What are the weak links in terms of strength? What about security? Are there any hazardous interactions between these items (as was the case in this Swiss accident)?

Thinking about the whole system is good, because it gets you thinking about failure modes -- which is more useful than counting "points of attachment".

Good question: "Do I have enough points of attachment?"
Better questions: "Am I secure? Could I become detached?"

 

[bograt]

Also worth considering is the difference between "points of contact" and "points of attachment", the climbing mantra applies to "points of contact", ie. two hands & one foot etc., if you are on a traverse with feet on one wall, shoulders on the back wall, I suspect that a cowstail from sit harness to traverse rope would be enough, as in three pionts of contact, one point of attachment, a free swinging traverse (tyrollean, zip wire or otherwise) would carry different guidelines.

 

[Bob Mehew]

Finger strength comes from the forearm muscle not the fingers themselves they are just made up of tendons and pulleys having a clenched fist wouldnt stop bloodflow to the forearm!

I accept I was incorrect in implying that the muscles which do the work within the fingers were in the hand.  The mechanism which comes into play during extreme contractions is in the muscle where a reduction in blood flow occurs due to the contraction.  Although there is some offsetting by increase in blood pressure, in extreme cases, the flow becomes insufficient to keep the muscle both supplied with nutrient and clear the wastes away.  That is why you gradually (or quickly depending upon how well conditioned the muscles are) loose your grip.

 

[caving_fox]

Quote from: caving_fox on Yesterday at 10:39:48 am
Most people's cow's tails are formed from one piece of rope. Hence are only 1 point of attachment anyway if the knot at the D ring fails.
But that's not a realistic scenario, unless you let your cowstails get really badly worn (i.e. the core is showing).

After all, we're rigging pitches with one piece of rope. Our harnesses have one D-ring, and one webbing/metal loop for closure on each side. The descender is one item. Failure of any one of these items would typically be fatal.

Well we're sort of looking at unlikely scenarios anyway. Most of the time you don't need cow's tails as you don't fall on them. And then if you fall they do hold....

you'll still routinely bump into many cavers whose SRT gear hasn't changed one jot; some still use their original set of cowstails. After all, it stands to reason that if it hasn't broken yet then obviously it never will.

from another thread.

 

[Mike Hopley]

...in extreme cases, the flow becomes insufficient to keep the muscle both supplied with nutrient and clear the wastes away.  That is why you gradually (or quickly depending upon how well conditioned the muscles are) loose your grip.

It's also simply a matter of strength. Your muscles get fatigued holding such a tight grip -- because the force required is too great to be supplied aerobically. Few people are strong enough to last long in this situation.

you'll still routinely bump into many cavers whose SRT gear hasn't changed one jot; some still use their original set of cowstails. After all, it stands to reason that if it hasn't broken yet then obviously it never will.

This is true.

I would categorise dodgy cowstails as zero points of attachment.