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Accident at Haus Rock near Keystone, CO (Petzl Shunt accident)

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Craig Faulhaber · · Unknown Hometown · Joined Mar 2012 · Points: 330

Hi all,

I'm currently in the hospital and am the climber in this story: https://www.summitdaily.com/news/crime/summit-county-rescue-group-saves-climber-who-fell-30-feet-near-montezuma/

I'm happy to answer any of your questions, but I will keep this brief. I was working a 10 foot section at the top of the route, Burning Down the Haus on TR solo using the setup in this Dave MacLeod video starting at about 13 minutes https://youtu.be/kd13IaWS8gQ?t=782 

So in short, I am on a Petzl Shunt with a non cross loading biner and stopper knots tied below me. I try the section, fall on the Shunt, brush, lower, try again, repeat. I actually finally got the sequence and was pretty happy, looked down at a fellow climber who was watching to express some psych, and decided to try one more time. 

This time, when I fell, I hit the ground. On the ground, the shunt and non cross loading carabiner were still properly attached to my belay loop. The rope and stopper knots were still in tact. The Shunt just came off of the rope. I was certainly not doing standard face climbing moves -- I was twisting, high stepping, etc. There were also draws hanging on the route that could have rubbed against the gear on my belay loop. 

I know that the Shunt is a back-up device or an ascender, so TR solo is not it's designed purpose. But has anyone heard of a Shunt just coming off of a rope? I figured it could pretty consistently grab a rope, and even if it didn't, the backup knots would stop me. Looking at the device makes it seem like an impossibility that it could come clean off of a rope, but I was clearly wrong. Anyway, I just wanted to ask if anyone has ever heard of something like this happening with a Shunt, and if not, I want to get the word out so that no one else tries to use this device for TR solo.

I ended up with around 12 breaks including L1 and L2 vertebrae, both heels, right elbow, sacrum, ribs, etc. No major spinal cord damage or head trauma. I should be able to stand in 6-8 weeks and hope to make a full recovery. I was extremely lucky and have started to and will continue to reach out to express all of my gratitude for everyone who unfortunately witnessed the accident and to those who helped with the rescue. Their presence, help, and expertise saved my life. 

Be safe everybody,

Craig

Peter Beal · · Boulder Colorado · Joined Jan 2001 · Points: 1,825

Wow Craig, lucky this didn't go far worse!  Shunts are definitely tricky beasts but once you're clipped in there is no way for the rope to get out that I am aware of. Mechanically a shunt is super simple but that simplicity can be a problem on steeper climbs since there is a good chance the rope won't catch right away. Another mystery is that the backup knots or whatever didn't catch you. A good practice is a maillon (some people use a chainlink) that will absolutely no matter what catch you on a BHK at least 10 feet off the deck.

This accident raises another point that has long bothered me, namely how hard it can be for people to find like-minded partners for projects like this and how TR solo etc is seen as an option. Ironically I had thought about checking this route out at some point this summer and would have been psyched to work it with you. Ugh.

Hope you heal up well!

aikibujin · · Castle Rock, CO · Joined Oct 2014 · Points: 300

Damn, Craig. Glad the outcome wasn't worse, and best wishes to you on your recovery! 

James W · · Unknown Hometown · Joined Aug 2021 · Points: 0

Interesting.  Makes sense, though.  I’m not a shunt user, but a quick look indicates the aluminum body likely got bent open like a spring and released the rope.  There have been numerous documented accidents where ascenders have failed the same way. I use microtraxions because they don’t have this failure mode - and I use 2 of them - both with the lock-open tab ground off.  The fact this is the most common setup also decreases the odds of unknown failure modes.  Good thing you were on a short climb - otherwise you’d certainly be dead.  

aikibujin · · Castle Rock, CO · Joined Oct 2014 · Points: 300
James W wrote:

Interesting.  Makes sense, though.  I’m not a shunt user, but a quick look indicates the aluminum body likely got bent open like a spring and released the rope.  There have been numerous documented accidents where ascenders have failed the same way. 

Can you point me to some of those documented ascender failures? I'm interested in doing some reading.

csproul · · Pittsboro...sort of, NC · Joined Dec 2009 · Points: 330

What were your backup knots? They clearly weren’t some kind of bight  that you were clipped into, were you relying on backup knots to jam onto a shunt that slipped but did not come completely off the rope?

Terry E · · San Francisco, CA · Joined Aug 2011 · Points: 43

Dunno if what I’m pasting below is applicable. From: https://cascadeclimbers.com/forum/topic/83561-mini-traxion-rope-soloing/?page=2

The Shunt typically slips rather than cutting the rope. If it hits an obstruction (knot in the rope, rope over an edge...) it will simply deform and blow right off the rope. It also appears (one study) to be very sensitive to rope diameter.

Most of my knowledge about Shunts is from the rope access world, and we use low stretch ropes. I'm not sure what effect dynamic rope would havbe on these properties.

Nkane 1 · · East Bay, CA · Joined Jun 2013 · Points: 465
Terry E wrote:

Dunno if what I’m pasting below is applicable. From: https://cascadeclimbers.com/forum/topic/83561-mini-traxion-rope-soloing/?page=2

The Shunt typically slips rather than cutting the rope. If it hits an obstruction (knot in the rope, rope over an edge...) it will simply deform and blow right off the rope. It also appears (one study) to be very sensitive to rope diameter.

Most of my knowledge about Shunts is from the rope access world, and we use low stretch ropes. I'm not sure what effect dynamic rope would havbe on these properties.

Do you still have the Shunt? Is it damaged?

Glad you're still with us and best of luck with recovery!!

Craig Faulhaber · · Unknown Hometown · Joined Mar 2012 · Points: 330

Thanks for all of the replies everyone! The Shunt actually was completely removed from the rope, so I didn't slide down, but just free fell through the air. The backup knots were just overhand knots meant to jam the device but unfortunately didn't get a chance to help. 

It does seem like some bending/torquing of the metal somewhere in the device must have happened. It seems that this would have been made possible or more likely by my high stepping which could have twisted things up in my set-up. 

I'm really interested to hear more opinions, keep em coming everyone!

Craig Faulhaber · · Unknown Hometown · Joined Mar 2012 · Points: 330

Oh, and no I haven't tracked the actual Shunt down yet. On my quick glance on the ground, it was at least intact. The climbers at the crag that day seemed to think it looked normal. I think the SAR folks have it, but I'll let you know if I can get my hands on it. 

Peter Beal · · Boulder Colorado · Joined Jan 2001 · Points: 1,825

That’s a lot force required to deform the body of a shunt to where it would pop off a rope 

Sorry the backup failed but it makes sense.

When using a shunt I almost always climbed using two strands, clipping to the anchor with a figure 8 on a bight, ensuring a backup strand if one failed. Also easy to tie the BHK a ways up and clip a locker into both strands 

Yann Camus · · Blainville, QC · Joined Oct 2017 · Points: 97

Craig: I am sorry for you! Be sure that I will continue to praise against using the Shunt for TRS. Your case will help convincing people to use other devices that is for sure!!! What rope diameter was it? What rope model? How worn / old was the rope?

Sirius · · Oakland, CA · Joined Nov 2003 · Points: 660

Glad you survived this catastrophe, and that you'll make a full recovery. Also appreciate your sharing the story here - accidents can befall any of us, always good to be reminded.

Second Yann's q above: what diameter rope? Finding it difficult to imagine how it could have come off the rope if it was properly engaged - and since you'd fallen on it already, we know it was properly engaged, right? Did you ever remove and replace the shunt when climbing, say, to rap on a grigri, as MacLeod shows in the vid? Not looking to find fault with you, just bending thinking toward pilot error over gear failure, since that's generally more common.

I use two mini traxions, though I used to use a shunt. Over years I saw enough long-toothed veterans around the valley - everywhere from the Cookie to the upper pitches of the Salathe, famous badasses to low-key locals - firing away on mt's, and figured I'd join the fold. So many aggregate hours on minis, never heard of an accident. 

When I started I used to tie backup knots and clip them to an autolocker on my waist, then gradually stopped clipping them to my waist (the method you were using) to avoid the cluster and poorer feeding of the device that comes with it. At some point I'm ashamed to admit I stopped using backups altogether, just the two minis. Complacency, idiocy. Your tale will have me back on course.

aikibujin · · Castle Rock, CO · Joined Oct 2014 · Points: 300
Terry E wrote:

Dunno if what I’m pasting below is applicable. From: https://cascadeclimbers.com/forum/topic/83561-mini-traxion-rope-soloing/?page=2

The Shunt typically slips rather than cutting the rope. If it hits an obstruction (knot in the rope, rope over an edge...) it will simply deform and blow right off the rope. It also appears (one study) to be very sensitive to rope diameter.

That's very plausible. The cross section of the Shunt is an open C. Even with the arm down and clipped with a biner (forming an E), there is nothing physically closing the C shape and preventing it from bending outwards. In Dave MacLeod's method, the backup knot is not clipped to the harness, but used as a stopper to jam against the Shunt. One possible scenario is that the Shunt failed to grab/slipped on Craig's last fall, so Craig fell far enough for the Shunt to hit the backup knot. Instead of stopping the Shunt, the knot acted as a log splitter and bent the Shunt outwards. The Shunt then became completely detached from the rope. Inspecting that Shunt closely will be very helpful.



Cherokee Nunes · · Unknown Hometown · Joined May 2015 · Points: 0

Thanks for posting Craig. Heal well. When you return I would suggest a 2-device strategy for future TRS.

James W · · Unknown Hometown · Joined Aug 2021 · Points: 0
aikibujin wrote:

One possible scenario is that the Shunt failed to grab/slipped on Craig's last fall, so Craig fell far enough for the Shunt to hit the backup knot. 

I don’t see that as mechanically possible.  My theory is that if you flip that thing upside down with your leg, the rope could jam between the cam and that taper in the top of the device (now the bottom), wedging the C open if you then fell.

K Go · · Seattle, WA · Joined Oct 2017 · Points: 142

Damn, that's scary, I hope you make a speedy recovery! Just goes to show that any given rope solo setup might work without a hitch for some people for a long while but that doesn't necessarily mean there aren't bizarre failure modes. Even with 2 devices (microtrax & CT Roll'n'Lock) separated and sometimes on different strands of rope, I still double check they are grabbing a few times on route (but I haven't filed off the locking mechanisms). 

Tim Parkin · · Ballachulish, Highland · Joined Jun 2018 · Points: 0

This might be of interest

https://www.hse.gov.uk/research/crr_pdf/2001/crr01364.pdf

"The third concern is over the Shunt’s relatively weak body strength. The Shunt is designed
to slip when overloaded and can be used on double or single ropes. The slipping function
negates the need for a strong body, as high forces should be impossible to reach. However,
if the Shunt is loaded when it is only a short distance above a knot on the rope, it will be
prevented from slipping by the knot and high forces could be achieved. This situation is
possible in rope access, and could result in the Shunt releasing the rope at forces as low as
4 kN. The problem is exacerbated when the device is used on a single rope, as would be the
case in rope access."

Hope you get well soon!

Bill Lawry · · Albuquerque, NM · Joined Apr 2006 · Points: 1,814

Tim Parkin’s information about the relatively weak body strength is sobering.  

I don’t own a shunt and have no experience with one.  

… wedging the C open …

Quoted the above just to spell out what is probably obvious to most:  the rope will also skinny down some under load plus perhaps some more with any added pinching if/when forced through a gap during whatever loading; in other words, the C shape may not need to open very much to release the rope and so may not have permanently deformed.

Also carefully inspect the rope? Seems a very long shot but perhaps there are some tell tale signs of trauma to it.

James W · · Unknown Hometown · Joined Aug 2021 · Points: 0

This failure mode of the device slipping down the rope and opening on a knot requires considerably more force than what the OP is describing.  If he told us the knot was more than 2 few feet away and there was not a long loop of slack built up above the device - 4 feet or more as in the video on a test fixture, likely more required if well below the anchor on a dynamic rope - then it most likely didn’t happen that way.  The video test load is over 300 lbs, 4’ drop, rope slips less than 2 feet.  This would be a memorable if not bruising amount of force.  OP seems to be describing a low force event.  My read is the device got flipped and the rope wedged its way out.

Bill Lawry · · Albuquerque, NM · Joined Apr 2006 · Points: 1,814
James W wrote:

OP seems to be describing a low force event.  My read is the device got flipped and the rope wedged its way out.

I don’t disagree, James. An upside down shunt, at the moment when the rope comes taught would bend the rope firmly across one end of the gap of the C (with lever arm involved) and so act as a wedge / force multiplier towards opening the C. This would be quite different mechanics than a normal upright slip down onto a backup knot and could require less force to failure as you say.

Even better if the upside down shunt were somehow held from righting itself. Seems it wouldn’t take much of an external holding force (if any?) because once the rope starts to wedge its way into the gap around the lever arm, the rope itself would tend to hold the shunt in the upside down position as it works along the gap.

Edit: For someone who has a shunt, and with a little care, the possibility of this might be confirmed (or denied) out in the backyard or at a city park with, say, big trees. Perhaps just weight an upside down shunt or even nearly sideways shunt with gap aimed upward and see if it tends to remain towards upside down and if the rope tends to begin to wedge into the gap between the body and the lever arm. 9.5mm rope might be representative 

Also in Tim’s reference was this quote from testing where the shunt slipped down but hit the knot before a normal stop.

“On all tests, the corner of the frame left a mark down the sheath as it slipped.”

A rope inspection might find some tell tale marks though the meaning of their presence or absence might not be clear since falls were arrested by the shunt before the failure one. If present, a description or pictures of them might be interesting. 

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