Ascent safety

Tom Dunlap

Tom Dunlap

Here from the beginning
Administrator
Location
Retired in Minneapolis
After reading the article and seeing the graphic picture of the climber who fell onto the iron picket fence I've had plenty of thoughts about ascent safety systems.

One question that goes through my mind is, "What can be done to reduce the chance of a climber falling?" Using two rope attachments that function independently of each other is one part of the solution.

What else could be done?

Several years ago Peter Jenkins and I talked about his concerns about having climbers in his introductory classes grabbing their hitch and sliding down the rope. Doing this without someone to belay or at least watch closely was his goal. But he had some climbers who would decide to descend on their own. He wanted a solution to this problem. What we came up with was adding a slipped half hitch at intervals along the tail of the rope. If the climber slipped their hitch would stop at the slipped half hitch...not the ground. This is a standard practice now for Peter's lessons.

Whenever I get a new rope climbing tool or hitch I spend the first few climbs with stopper knots in my rope. Until I have a complete understanding of how the new tool/technique functions I want to make sure that I don't fall or hit the ground.

Even after I have become comfortable with the new tool I will still tie-off stoppers at intervals.

Something that I'm considering is adding stoppers at intervals on all of my ascents.

How would this be accepted in general practice?
 
I feel that slipped stoppers are something I could get used to if I really thought they were necessary. It would have to be equalized with the need to bail out quickly. They may add safety on the way up, but if you require a speedy descent, you'd find yourself stopping to untie a knot every couple meters. Of course, using a trunk belay would allow a groundie to lower you regardless.
 
If the slipped half hitch is tied correctly the groundie can tug on the rope and invert them from the ground. Not a perfect solution but better than taking a groundfall.
 
I understand where you are coming from Tom but there has to be a point when to say enough is enough. We work in a dangerous business. We work aloft and one mistake means big problems. If we need stopper knots every 10 feet in our lines I personally think we are in the wrong field.

I'm serious about safety. That’s one of the main reason why I joined the site and started exploring other venues of information not only from here but others. If you don't test things out or seek expert training before using them you might have a problem. Sadly a small problem in this business is a hospital visit.

Seeing that saddle on the fence was an eye opener for me to watch what I'm doing even closer than before.

But putting knots in our lines will not only slow production down (yes I said it) but it could cause other problems in the descent or even future accent. They might get stuck in branches and other tight spots, another thing to keep track of, and just over all restricts movement.

Just my two cents but headed in the right way
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I've been thinking exactly the same thing Tom.

Over the past three days of sleepless nights, I've been updating my risk assessment and justification for safe use of the Frog.

We all know what this dog is like when it gets a bone - I'm not happy until I've sucked out the marrow
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This ivolved trawling through reems and reems of research and test results on anchor forces and worst case scenarios for caving equipment and roped access, plus manufacturer recommendations for the specific equipment I use in the technique.

The main risks are:

1. Rope unclipping from device
2. Anchor failure
3. Device failure to grip the rope
4. Fall force of rope catching a second anchor
5. Device seriously damaging and weakening rope

To keep this short, I am now fully satisfied that the equipment compatibility in the two systems I use - Frog with ground belay, and RADS choked to limb - is safe to use in worst case scenario, with nothing greater than a 6kN force. THE ROPE IS AS IMPORTANT AS THE DEVICES.

The provisos with rare exception are:

1. I only use Frog for access.
2. I only use Frog with ground belay (huge amounts of energy absorption from rope available for favourable fall factors as approaching anchor).
3. I only work off choked TIP line with RADS.

The five main risks are easily avoided.
 
The only likely way I could hit the ground, is if both cams PERMANENTLY failed to grip the rope at the same time. This has never been recorded, in caving or industry (please tell me if anyone knows otherwise). This is probably because in the Frog with a chest ascender, one or other cam is levered against the rope at all times. Once these devices are loaded, they are extremely difficult to disable. This is a remote risk.

But even if it did happen, a knot in the line would jam in the device to prevent a ground fall. However, we are talking extremely high forces way beyond Factor 2 fall, similar to via ferrata risks - many metres of fall with only the low stretch rope payed out for energy absorption.
Preferable to a ground fall, but serious internal injury likely.


If paranoid about both cams permanently failing, here is a simple solution:

1. Pull up the access line to the TIP, and over.
2. Tie an alpine butterfly at ground level in the access line.
3. Clip in the end of your work line.
4. Set access line with trunk wraps, with butterfly just below TIP. Tie access rope ends together if required, to ensure the climber can be lowered to the ground.
5. Attach to access line with Frog.
6. Attach to work line with Rocker.
7. Proceed with Frog to TIP. End of Work line is waiting to go to work.

With a Frog Walker, the Pantin can go on the work line, and your usual self tending hitch instead of Rocker. This way, when you get to the TIP, the workline combo is ready to go.
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If the Knot is stretched below the TIP, the Frog is easy to safely pass the knot. Its why it was designed - to easily pass re-belays in alpine caving technique. Normally its close enough to just pick-up the work line and re-crotch.
 
Using a self tending hitch as back-up in this way has the usual disadvantage of the climber grabbing and disabling the hitch in the fall it is designed to prevent.

A back-up attached to the sliding bridge needs to be able to dissipate fall arrest forces, as it will trail below the centre of mass of the climber. Prusiks on a single line that I tested in this manner, actually did a good job of reducing fall forces. They weld to the line though.

Tying knots in a line as back-up is a mountaineering control measure, based on energy absorption in a payed out dynamic rope.

It would have merit in a Texas system on a low stretch line, with a via ferrata lanyard as attachments to the two ascenders.

In a Frog the knot would crash into the Chest ascender with high forces that would probably rip it free. This may jam in the upper ascender and deploy an energy absorbing lanyard to safely arrest the fall. Maybe. But the force that would cause the chest ascender failure may injure the climber.
 
So, to answer the question, I don't believe knotting the rope is necessary or effective. A ground fall may be more survivable than rupturing internal organs in a via ferrata type fall. Depends upon how many knots!!!

I believe that two primary attachment points that are redundant to each other, is a reasonably practicable control measure.

Any concerns, I'd clip in my work line to the system. I've got to take it up somehow anyway. might as well offer potential support as hang off my harness.

As the knot is clipped before removing the work line, there isn't a period of exposure during change over either.

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It wouldn't.

Reading and applying this does:

http://en.petzl.com/petzl/frontoffice/Sport/static/services/ASCENSION/B17_en.htm

Cams don't just 'come off' the rope, especially at the same time.

The same risk applies to the pip pin, R clip or slot pin of shelled cams.

Prusiks don't just slide of their own free will.

All protection devices and ropes have safety and practical use limitations.

As explained - If paranoid about any of these devices, clip the work line to the ascent line and use a third measure.

If thats not enough, quit driving, walking stairs, walking side walks, eating cheese...................living a life is a risk. But not as big a risk as not living it.

But I think you know that.

Two cam devices, secured to the rope and climber, as explained in the Petzl link, is redundancy and reasonable risk.
 
Tom, your question of what can be done to reduce the chances of a climber falling is, as you know, not a new one.

We have all been racking our brains and people before us racked their brains on how to get this job done without killing or maiming the workers. Some tremendous advances have been made in techniques and equipment and materials that have facilitated accessing a tree.

In some ways this has increased safety but at the price of increased complexity. Many activities that are extremely dangerous, if done with competence, can become routine. Downhill skiing, gymnastics, sky diving, and the list goes on. What makes the practitioners of these activities safer is, not so much their protective equipment, but the knowledge in its use and their experience in using it, added to their own competence in that activity.

There are many who will not want to hear that tree climbing may not be right for them. They will probably be as disappointed as I was when I realized my lifelong ambition on flying culminated with repetitive airsickness. I couldn't believe I could get bounced around in the trees in the wind, hang upside down, spin around and feel great...yet throw me up in a light weight aircraft with a little bit of turbulence and all I could think about was vomiting.

For me, flying was not in my best interests.

Many who show physical and mental aptitude for tree climbing can pick up equipment and gear use quickly. Many of the guys I worked with could learn primary techniques within a week. But the application of those techniques and the body's response to awkward situations is only achieved over a period of years. During this time the new climbers are vulnerable. A loss of balance may create an instinctive movement that could get them into serious trouble. I don't see that as an equipment failure.

I just don't see anyway around the time factor involved in the process of acquiring the experience and knowledge to BE safe. This is why I feel so strongly about apprentice/internships for guiding the new tree worker during this time of learning.

Dave
 
Sometimes DSMc, your posts are all that keep me sane.

Can I have one a week please - stop me pulling my hair out?

My wife would really thank you for it.

This is relevant:

"The advantages of rope access and similar work systems do not derive from the equipment
employed alone. The motive force for the system is provided by the operative. The worker and
his/her equipment combine to form a machine. This machine only functions as well as the sum
of its parts. The ropes and devices are essentially passive, the dynamic element is provided by
the worker’s strength and skills. The worker is required to have the intelligence, as well as the
strength, to work in this way. It follows that this method of working requires rigorous training,
practice and assessment before the equipment investigated can be used effectively and safely."

HSE contract research report CRR 364/2001.
 
Dave,

I appreciate your comments.

If the tops of the Kongs were clipped to hold the rope into the shell there is a chance that the climber would not take a grounder.

Agreed, a proper apprenticeship under a proper mentor is a good way to have a good career. When our profession has training programs as stringent as flying then we will see a decrease in accidents.

Until then we make incremental changes and try to inject them into the workplace. At the end of the day though I feel a bit underpowered. This Kong accident is a case in point. It's been known for a while that moving off of a vertical will pull the rope to the side of the shell. This can be enforced during comps and hopefully the comps can be a place where details like this can be injected back into day to day processes. But obviously this climber was never taught NOT to work off lead or to clip the top or to have two attachments to the rope.

Working off the ground is a dangerous place. Maybe the entry fees should be raised.


"Somethin' happened when we fell out of the trees, took a look around and we straightened our knees." -Colin Leyden
 
[ QUOTE ]
Dave,

[...] But obviously this climber was never taught NOT to work off lead or to clip the top or to have two attachments to the rope.

[...]

[/ QUOTE ]

This has me wondering... that was a Treemotion harness, right? It's not proof positive by any stretch but it leads me to believe he is an intermediate climber at least, likely enough he's advanced.

In other words, he knows better than to do climb without backup... he SHOULD know not to side load that Kong. Was it just false confidence?

No point really, just speculation.
 
Some of us may re-evaluate the usefulness of these cammed ascenders. Think about ascending with a triple Prusik system, is there any way that any one or indeed all three Prusiks could fall off the rope? No way.

The problem with most ascenders is that they are "quick release" devices, very easily detached from the rope. Any other device with a quick release feature has to be modified so that it cannot fall off the rope (i.e. Gibbs ascender etal.) The solution seems simple: if using a quick attach/quick release device it MUST be backed up with a cord tied hitch to prevent it from releasing it's purchase on the rope.


$0.02
 
[ QUOTE ]
Some of us may re-evaluate the usefulness of these cammed ascenders. Think about ascending with a triple Prusik system, is there any way that any one or indeed all three Prusiks could fall off the rope? No way.

The problem with most ascenders is that they are "quick release" devices, very easily detached from the rope. Any other device with a quick release feature has to be modified so that it cannot fall off the rope (i.e. Gibbs ascender etal.) The solution seems simple: if using a quick attach/quick release device it MUST be backed up with a cord tied hitch to prevent it from releasing it's purchase on the rope.


$0.02

[/ QUOTE ]

The prusiks can slip and bump each other down.

Not very efficient either. And too many variables.

quick release deices are inherent to quick attach devices, expedient to productivity. The answer is redundancy.
 
I had a fall involving kong ascenders and i think it comes down to one thing we need better ascenders. At my local isa conference i got to talk to the ISC rep and talked to him about adding a locking pin to one of their already well built hand ascenders, this would prevent the cam from coming of the rope. they already have these locking pin in other set ups. The pin would slow things down when it comes to putting the asenders on the rope but that does no matter.
Every arborist need to talk to their rep and demand better equipment.
 
[ QUOTE ]
I had a fall involving kong ascenders and i think it comes down to one thing we need better ascenders. At my local isa conference i got to talk to the ISC rep and talked to him about adding a locking pin to one of their already well built hand ascenders, this would prevent the cam from coming of the rope. they already have these locking pin in other set ups. The pin would slow things down when it comes to putting the asenders on the rope but that does no matter.
Every arborist need to talk to their rep and demand better equipment.

[/ QUOTE ]

I was thinking the same thing. They are down the road from me and I know Denny - time to pop in for a chat.
 
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