Rappelling accident using Mad Rock belay device.

From Wolfe County Search & Rescue Team's Facebook page:

As previously reported, our Chief was involved in a rappelling accident on the night of July 4th. We felt it was important to share our conclusions of the incident. On the morning of July 5th, Chief May, Deputy Chief Hackett and Training officer Ryan completed an AAR (After action report). During the AAR, the equipment that was used, how it was rigged and photos along with first hand reports were all evaluated. We also discussed the setup and equipment that was used with outside sources for additional evaluation. Our summary follows: Chief May was rappelling on a 240’ 10mm dynamic rope using a climbing belay/rappel device. A 6mm pre-sewn Prussik cord, with 4 wraps was in place as an autoblock or conditional belay. Chief May weights 252lbs and was carrying and additional 20lbs of gear counting his pack, harness and rope equipment.

During his rappel, he noted some difficulty in controlling his speed of descent and was unable to come to a complete stop. As he continued down the cliff with his feet still in contact with the cliff face, his speed was still under control although faster than you would like. At approx 90’ from the bottom, his feet were no longer able to make contact with the cliff face, his descent speed became rapid and the friction of the rope began to burn his hands. Chief May then descended through some large trees before making impact with the ground.

This particular rappel device is designed to operate 10mm rope without adding the “pin” used for smaller diameter size ropes. We have concluded that with the total weight of Chief May and his equipment, along with the stretching of the dynamic rope (which decreases the overall diameter of the rope) the device did not adequately control his descent. During the initial part of the rappel, the weight of the rope hanging below him partially helped maintain control, but as he lowered further down the cliff, this effect was reduced. As a result of his speed and how quickly this all occurred, his autoblock did engage but not sufficiently to arrest his fall (Pics below show the rappel device that was used and the burn thru on the autoblock/6mm pre-sewn cord).We train to never let go of the rope and from the burns on the Chiefs hands, that never occurred. It was also noted that the autoblock never came into contact with his rappel device during his descent.

In conclusion, our internal after action review has determined the system was rigged within manufacturer recommendations and backup safety measures were utilized appropriately. However the combination of this particular rappel device and the overall rappelling load may have a contributing factor. We will be evaluating how this specific rappel device will be used with the team moving forward.

 

Is your chief going to be alright?  I hope so.

You say :"on a 240’ 10mm dynamic rope ".  Was it a single-strand rappel, or were two ropes used? ...and if it was single strand, was that within the design spec's of the device?

Re' the burning of the prussic:  Decades ago a climbing friend who was a Professor of Engineering told me that the "mathamatics of a prussic back-up doesn't work."  In that the energy of a 250 lb climber descending at even a modest out-of-control speed generates enough heat to melt the mass of cord in contact with the main climbing rope. (You'll note that the prussic cord doesn't even have to melt completely through to fail, only melt enough to make the surface "slippery", after that it won't grab.)

  I don't have the engineering knowledge to check that, but it seems reasonable. (Look at how burned your hands get holding all of your weight and sliding down doubled ropes for even 1 or 2 feet)  

  I always look at my prussic back-up as something I engage after I stop to remain stationary while I do something...like to clear a snarl, look for the next anchor, etc.

 Gloves also help a lot in terms of absorbing heat. Don't know if your chief was wearing them, but they should be std.

 Also, the device itself doesn't seem to have much mass, so it probably got pretty hot just about the time the chief went into the free part of the rap.  Was there any evidence of even a small amount of melting of the main rope's sheath?  That would have reduced friction through the device.

An ATC type device like this should be fine for a 2-strand rappel.
When you go to single strand, that's half the friction.
Should generally use a Munter hitch instead of an ATC for single strand on a smallish diameter rope.

Whenever starting a rappel with a single strand:
Add more friction than you think you will need, by wrapping the rope around your thigh twice.
This is the way the pro rappellers do it, too - they have a series of brake bars and start with the rope through all the bars.
Then if the friction is too high, you remove some of the friction, like removing one of the thigh wraps.
If one thigh wrap is still too much friction, then remove it but pass the rope under your butt and hold it with the opposite hand.
You can adjust this a lot by changing your hand position.

I think the use of the autoblock was a contributing factor to the accident.
Perhaps the Chief thought it would somehow save him if he got going too fast.
But it can't generally do that.

I would never rap at high speed unless I had tested ways to stop myself (glove and move rope under your butt is the simplest way).
And it would be wise to put a big knot (like a figure eight on a bight) down near the end, high enough to keep you from hitting the ground if you lose control (in this situation it sounds like he hit trees which may have saved him).

 

Did he have the shrink wrap in the wraps of his auto block? In my experiences I have found that increases the bend radius of the friction hitch enough to affect how well it grabs overall, has any one else experienced that? Was the shrink wrap in the friction hitch or does it just appear that way because it experienced burning after making contact with the rope during decent?

Something is odd here. The friction hitch alone should've been enough to stop him even with the belay device not working as intended. Did the chief test that his friction hitch was catching before he set off on his rappel?

I am wondering if maybe he's used to double strand rappels and then went to do this single strand rappel. But of course if you do that you have to adjust how many wraps you do around the rope, and you have to test it actually catches. Of course this is total speculation on my part but I find it really odd that his prussik didn't fully catch.

Some thoughts:

-That super sucks, and I hope for a speedy recovery!
-I’ve observed climbers holding on firmly to their auto block/prusik/etc. When one holds onto them firmly, they are not allowed to slide up the rope and lock. Could be a possibility in this situation.
-Single or double strand rappel will make a huge difference on whether that backup had a chance to catch.
-Why is the sewn part of the auto block burned? That shouldn’t have been in the auto block when wound around the rope. Possibly mis-installed? Mike G hits this “Did he have the shrink wrap in the wraps of his auto block?”
-Adding another carabiner into the rappel is a great way to add friction. See #2 in this article.
-Not to be glib, but why was no one on the ground giving him a fireman’s backup?
-Gloves, gloves, gloves.
-If he felt he was not in enough control of the rappel, wrapping the rope around his leg (even while descending) would have been great.
-”However the combination of this particular rappel device and the overall rappelling load may have a contributing factor.” Nailed it.
-”I think the use of the autoblock was a contributing factor to the accident. Perhaps the Chief thought it would somehow save him if he got going too fast. But it can't generally do that.” Clint also hits it on the head. 
-I hope for a full recovery!

Mike G wrote:

Did he have the shrink wrap in the wraps of his auto block? In my experiences I have found that increases the bend radius of the friction hitch enough to affect how well it grabs overall, has any one else experienced that? Was the shrink wrap in the friction hitch or does it just appear that way because it experienced burning after making contact with the rope during decent?

It does look like the shrink wrap was burned right in the center. I can't see how this would have happened unless it was included in the friction hitch.

A J wrote: Something is odd here. The friction hitch alone should've been enough to stop him even with the belay device not working as intended. Did the chief test that his friction hitch was catching before he set off on his rappel?

I am wondering if maybe he's used to double strand rappels and then went to do this single strand rappel. But of course if you do that you have to adjust how many wraps you do around the rope, and you have to test it actually catches. Of course this is total speculation on my part but I find it really odd that his prussik didn't fully catch.

I've noted in a few long rappels that the weight of the rope itself acts as a light "fireman's belay" by weighing down the brake strand. This effect is largest at the top of the rappel, because there's more rope below you to apply weight to the brake strand, while as you descend, the amount of rope weight below the device decreases. This can mean that a Prusik which holds at the top of the rappel may not hold near the bottom, because it doesn't have the added help of the rope weight.

Hi David, in my experience, either the friction hitch "catches" and you can't pull any rope through it, at all, or it doesn't catch and then it's just acting to keep the brake strand in the brake position, which helps but isn't much. To me if it's not catching then more wraps need to be added. I understand what you mean by the weight of the rope acting as a fireman's belay - maybe that contributed by making Chief May think his setup was good when the friction hitch wasn't truly catching.

Edit: the other likely possibility is that he forgot his right hand was on the friction hitch (because of the half gloves he was wearing he wouldn't necessarily have felt it), kept clamping down on the friction hitch as the rappel got faster and defeated it without realizing it. That would explain how a properly rigged hitch would fail.

title of the post is misleading, implies that there is something wrong with mad rock belay devices. A relatively heavy dude was doing a single-line rap, didn't have adequate friction and lost control. 

Anybody ever hear of something called a prussik?

Zachery Smith wrote: Anybody ever hear of something called a prussik?

And your point is?

Cosmiccragsman AKA Dwain wrote: And your point is?

He Just joined, ignore the troll.

This device has a kind of lever to decrease the friction. If rigged backwards for rappel, it might be easy to hook the thumb or fold of a glove (?) in a way that could lever the device more “open” while pulling down on the brake strand.

But looks like it might be awkward to rig backwards

Adding a second locking biner (opposed gates) to the rap rig appreciably increases friction. Maybe a third biner if riding a pig.

Forgive me for being a newb but in arborculture we use heat resistant(starts to melt around 900°f) prusik cords that are designed to deal with this extra friction/heat. Do climbers not know about rope such as this? Or is this just not something most are concerned with?

The SAR agency might be able to answer your questions if you ask on Facebook. I didn't see much discussion there, but there could be. I've done a single line rap from the upper ramp in Eldo on an ATC and it was controllable, but just barely towards the end. Of course the issue with rappels over 150 feet on devices like ATCs and regular figure 8s is overheating and the resultant decrease in friction, which eventually is from slight melting of the rope sheath. I often need to wrap the rope around my leg to slow down on newer ropes, which is what this guy should have done and was also mentioned by caughtinside. Another reason I posted it is to show that these rappel backups seldom work in an emergency as they don't automatically engage, but rgold can tell you that again if you missed it before.

The point is, do learn how to quickly wrap the rope around a leg to add friction when you realize you are going too fast on a rappel. This can completely stop you and allow you to fix the issue. Practice it. You can even keep the leg wrap all the way to the ground.

Josh Roberson wrote: Forgive me for being a newb but in arborculture we use heat resistant(starts to melt around 900°f) prusik cords that are designed to deal with this extra friction/heat. Do climbers not know about rope such as this? Or is this just not something most are concerned with?

It seems like most climbers just use tied loops of nylon accessory cord. Some use more specialised cords like the Sterling HollowBlock, which can handle high friction: https://sterlingrope.com/store/climb/cordage/sewn-cord/hollowblock2

Eli W wrote:

It seems like most climbers just use tied loops of nylon accessory cord. Some use more specialised cords like the Sterling HollowBlock, which can handle high friction: https://sterlingrope.com/store/climb/cordage/sewn-cord/hollowblock2

Yes the hollowblock2 is heat resistant but his was the original that is just cord.

From their FB page - Wolfe County Search & Rescue Team:  

“... the rappel line rubbed against it during the rapid descent. It wasn’t part of the four wraps.”

“He was clearly wearing thick rappelling gloves just to clarify any misconceptions. The burns suffered were primarily above where the fingers in the gloves stopped.”

“The rsppel device was not extended amd the autoblock was clipped to the ... leg loop.”

“unfortunately, we don’t know exactly what happened after his descent started. We believe the Chief Might have clamped down on the autobloc once his rapid descent began which is a natural but incorrect action. His memory of most of the rapid decent is vague from his concussion other than knowing it all went sideways when he got into free air about 1/2 down, seeing the approaching tree tops and the impact to the ground.”

... somewhere in the comments it was noted that he was the first one down so fireman’s not possible.  Burns were on both hands though more severe on his dominant hand (brake hand). And he is reported as a strong fit guy.

I wonder if the autoblock might have been able to catch and do its job if the rappeler had extended his device with a sling or something?  I've found that I've had little luck getting backups to catch when my ATC is attached directly to my harness; there's just not enough room in the brake-strand rope for it to fully tighten.

Of course, the most simple way this accident could have been prevented would have been a gri gri.