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curt


Feb 28, 2006, 5:07 PM
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Accident analysis - Shelley Windsor
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The following is an analysis I wrote up a couple of months ago regarding Shelley Windsor's fatal rappelling accident at Paradise Forks, AZ. I had inputs from both Dale Fox and Daniel Arlitt, but the report is mine. So, if something in this analysis appears incorrect or unclear--don't blame them.


On November 13, 2005, Dale Fox, Daniel Arlitt and I visited the scene of Shelley’s fatal November 5th rappelling accident. Accompanying us were two of Shelley’s brothers, Jim and John, one sister, Stacey, and her brother-in-law, Eric. Meeting us at the scene were two members of the Coconino County Sheriffs’ Search and Rescue team, one of who (Cpl. Aaron Dick) was in charge of their investigation of this accident. Cpl. Dick was also present during the rescue effort.

Our primary goal was to try and establish the probable cause of the accident, as best we could. To do this, we wanted to construct several rappel set-ups using the actual tree and the two actual slings of blue one-inch tubular webbing that Shelley was rappelling off on November 5th. Unfortunately, the two slings in question are currently missing and nobody knows where they went. Fortunately, however, Cpl. Dick photographed the two slings believed to have been used in Shelley’s rappel anchor against a rock at the bottom of Paradise Forks on the day of the accident. By laying out some one-inch sling material that we brought with us against this same rock, we were able to fashion two slings that must be fairly close in length to the actual slings that Shelley was using on the day of her accident. An independent “scaling” method of sling length determination, which Dale applied to the photograph of the slings, confirmed the length we determined in the canyon bottom.

For the record, we were able to establish that each of the two pieces of webbing used to tie these slings had a minimum length of approximately15 linear feet and could have possibly been a bit longer than that. In Cpl. Dick’s photograph, the two slings are each tied into separate loops using water knots. The tails of the water knots appear to be approximately 3” long.

In trying to recreate various rappel failure scenarios that could have led to this accident, we considered any possibilities that were consistent with the known facts and the eyewitness description of the accident as described by Shelley’s climbing partner on the day of the accident. Those things include:

- A single tree was used for the rappel anchor. This tree measures 72” in circumference a few feet above the ground and 77” in circumference just above the top of the root system.

- This tree sits on level ground and access to it is not obstructed from any direction.

- The distance from this tree to the edge of the top of the cliff was measured to be 31 feet.

- The rappel set-up consisted of the two slings described above being placed around this tree--and being clipped into using a single Chouinard Black Diamond auto-locking carabiner. Also connected to this same carabiner (via a figure-eight knot on a bight) was the end of Shelley’s rappel rope, as this was a single line rappel set-up.

- Shelley was connected to this rappel rope by her rappel device and a second locking carabiner.

- No additional gear was used in forming this rappel set-up.

- When this rappel failed, both slings came off the tree and the two individual and separate loops of one-inch webbing remained locked into the Chouinard auto-locking carabiner and this is how they were originally found at the base of the canyon where Shelley landed.

- Before Shelley rappelled on this set-up, she tested it by pulling on it—and it held. However, as she fully weighted the rappel at the edge of the canyon, the rappel failed and she fell to the canyon bottom.

We were able to create three scenarios more-or-less consistent with all the facts and eyewitness information described above. Two of these three scenarios involve incorrectly tied or used girth-hitches to join the two slings together and the third scenario involves the two slings not being clipped into properly with the anchor carabiner.

In the first scenario, one sling is passed through the second sling but then not passed through the other end of itself. If one then believes that a true hitch has been formed, and one then pulls the end of the loop not having the water knot in it, it is fairly easy to get the water knot to get stuck in the second sling—particularly when the slings are pressing up against the side of a tree. We were able to then pull on the two ends of the incorrectly joined slings with considerable force before being able to get the water knot in the first sling to finally “pop through” the loop of the second sling.

In the second scenario, the two pieces of webbing are joined with a “lark’s head” knot, rather than a girth-hitch. A lark’s head knot is formed by taking one piece of webbing and girthing it around both sides of the second sling’s loop—rather than being tied through the loop, as for a girth hitch. If this is then pulled until the end of the second sling almost enters the girth-hitch, it can visually appear to be a correctly tied girth-hitch unless it is inspected carefully. This is particularly true if both slings are made from webbing of the same color—as Shelley was using.

It should be noted that the lark’s head knot is fine, as long as both loops of the second sling are clipped into, however clipping into only one end of the second sling leads to a dangerous situation. As in the first scenario, we were able to pull on the two ends of the improperly joined slings with considerable force before being able to get the end of the second sling to pull through the loop of the lark’s head knot. One plausible explanation for the existence of a lark’s head knot would be if the two slings were joined together in that manner prior to being used in this rappel set-up, and they were not completely taken apart before being used for the rappel.

The third scenario involves placing each of the slings around the tree independently and then passing both water knots through the loops formed in the other ends of the slings—essentially girth-hitching the tree. Then, instead of correctly clipping into the ends of the webbing where the knots are, the other loop is clipped. In some cases, the knots would catch in the loops formed by the other ends of the slings well enough to hold the set-up on the tree, particularly if the slings are considerably twisted.

Analysis:

Each of these scenarios will result in the two independent loops of one inch webbing detaching from the tree and remaining locked in the anchor carabiner when the rappel set-ups fail. Either of the first two scenarios can result in a bad rappel anchor that will still resist vigorous tugs and pulls on it before failing, giving the false impression that the anchor is good. It was much harder to fabricate the third scenario and it could not be done reproducibly around the actual tree that Shelley used. Nonetheless, the third scenario cannot be ruled out. Additionally, although the third rappel set-up did not stand up to the same vigorous tugs and pulls that the other two scenarios did--before it failed--it isn’t clear exactly how rigorously Shelley tested the rappel prior to weighting the rappel rope at the rim of the canyon.

It should be noted that Shelley’s climbing partner on November 5th remarked that the slings appeared to be “messy” or “wadded-up” around the tree and that would appear to favor scenario three. However, it is also possible to place the knots in scenarios one and two on the front side of the tree—and then wrap them in opposite directions 360 degrees around the tree and join them again in front with the anchor carabiner. Done this way, scenarios one and two are not so different visually from scenario three.

It has also been noted by several of Shelley’s climbing partners that she always backed-up her anchors and rappel stations and that none of these scenarios is consistent with her normal practice. Although that incongruity remains somewhat of a mystery, it is clear that this particular rappel anchor was not backed up. And, to paraphrase Sir Arthur Conan Doyle, “When seeking the answer, first eliminate all things impossible. What remains, no matter now improbable, must be the answer.”

Possible contributing factors:

This involves a good deal of speculation, and as such, this section should be taken with a grain of salt. Nonetheless, it may be possible to get some additional insight into this accident by considering a few additional things. It was well known to several of Shelley’s climbing partners that she was anemic. She posted this fact on her own personal website--and Shelley noted that she regularly took blackstrap molasses and orange juice in the morning to keep her metabolism on an even keel. A few symptoms of anemia can be dizziness, lightheadedness and poor concentration and cognitive ability, according to several websites, including www.bodyresults.com, an outdoor sports website. Additionally, Shelley’s climbing partner on November 5th has reportedly told some people that Shelley was eager to get to the bottom of the canyon in order to find a suitable place to go to the bathroom. He also reportedly told those same people that the climbing pack containing their water was down in the canyon and they were eager to get to the water, because both of them were thirsty. This is, of course, second-hand information and we have attempted to get direct confirmation of these reported comments from Shelley’s climbing partner. Unfortunately we have thus far been unable to do so. I was told that he did not wish to speak any further with us about the accident. In any event, it is difficult to say whether rushing to rappel down into the canyon, or some disorientation due to anemia played any role in this accident. However, this information has been included here because none of this information is inconsistent with making a careless error when constructing a rappel station.

Summary:

We were able to recreate three different failure scenarios that are consistent with the reported finding at the bottom of the canyon--that both loops of tied webbing were still clipped into Shelley's locked anchor carabiner. Two of the scenarios involve improperly tied girth-hitches and the third involves improperly clipping the anchor carabiner into the slings that were around the tree. It's somewhat unfortunate and frustrating--but I have come to the conclusion that we may never know the exact sequence of events that led to Shelley’s accident.

What we have been able to establish is that each of the three possible rappel failure scenarios we created involved a simple error that could have been easily avoided by double-checking the rappel set-up. I believe Dale will be providing some pictures that he took of the various rappel set-ups described above. These will hopefully add some additional clarity to my verbal descriptions.

Curt Shannon


bhilden


Feb 28, 2006, 5:36 PM
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Yes, Curt, we may never know the exact cause. However, you have identified three possible scenarios that can cause such an accident. This is critical information that we can all learn from making Shelley's death not be in vain.

Bruce


roy_hinkley_jr


Feb 28, 2006, 5:54 PM
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This thread will deteriorate rapidly without photos. The knot descriptions leave a lot of room for misinterpretation. Would be nice to see the actual scene too but that isn't necessary.

Thanks for the effort!


dingus


Feb 28, 2006, 5:57 PM
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Thanks Curt.

DMT


tradrenn


Feb 28, 2006, 6:15 PM
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Curt and others, thank you for investing your time and effort in this invastigation.

I greatly apprecieate this report.

Thanks.


gordo


Feb 28, 2006, 6:32 PM
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Thanks for the report Curt. It's pretty well what was said before, but it's a good summary.

For what little it matters, I was really affected by this accident. After reading the likely reason for the accident in the original thread, I went out and bought a very large selection of sewn slings, as well as longer tied slings, to avoid the exact scenario that befell Shelly. I've girthed 2 and even 3 slings together on several occasions, and now I have a good reason to avoid that whenever I can.

Perhaps I'm not the only one who learned a lesson from this tragedy.


veganboyjosh


Feb 28, 2006, 6:59 PM
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thank you, curt, and to all those who assisted in this report.


healyje


Feb 28, 2006, 7:25 PM
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Curt,

Thanks for that report. In the end I think about the only thing there is to conclude is the need to assemble multi-sling anchor components in-hand up and apart from the tree and double-check the knots/hitches before wrapping around the tree or other feature. Your comments both here and previously regarding same color slings also bears note that such situations require even more diligence when check a system is rigged properly.

Again, thanks for you and the analysis team for all the work on this one...


docontherock


Feb 28, 2006, 7:38 PM
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Thank you, Curt, for putting the time and effort into this write-up. It goes without saying that we all should be constantly vigilant in checking our partners and ourselves when setting anchors/raps and your analysis provides us all with specific pitfalls to avoid. So sad that many of our "lessons learned" are written in blood..... My condolences, once again, to all who knew and loved Shelley....

EBH


Partner philbox
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Feb 28, 2006, 8:10 PM
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I too will add my thanks to you and your team Curt. Much obliged to you for heading out there and trying to recreate the scenario and for posting the results here.

Phil...


moose_droppings


Feb 28, 2006, 9:24 PM
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Thank you Curt and the rest that helped in what must of been a very heavy hearted endeavor.


billl7


Feb 28, 2006, 9:51 PM
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When Curt first mentioned the possibility of a knot catching and mimicing a correct hitch during a bump test, I was floored; I'll never think of the bump test in the same way. Thanks Curt and others for the reminder of preceding the bump test with careful action/inspection - and for the effort behind this summary report.

Whether a factor in the accident or not, the notes about possible distractions are meaningful to us all.

Bill L.


whoa


Mar 1, 2006, 11:10 AM
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Another possibility (two ways it can happen).

http://groups.msn.com/...=4675562346648401550

http://groups.msn.com/...=4675562347733055773


majid_sabet


Mar 1, 2006, 1:37 PM
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Great job Curt

If this was an experiment anchor setup then, it cost a lot and we will never know why.


paganmonkeyboy


Mar 1, 2006, 2:46 PM
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Thank You Curt.

-Tom


oldrnotboldr


Mar 2, 2006, 10:00 AM
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Thank you Curt and everyone else involved with this quite thorough report.


reno


Mar 2, 2006, 4:07 PM
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I want to say thanks to Curt and company as well. Excellent report, and I am sure that many folks appreciate your efforts.


boulderinemt


Mar 15, 2006, 4:18 PM
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i'll add in my own appreciation and thanks to you and your posse curt. thank you for everything you did for us around here, very well done.


pyramid


Mar 18, 2006, 6:31 AM
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I just want to say one thing, climbing is an unforgiving sport. You have
to do certain tasks over and over, and do them correct every time. Unlike
other endeeavors one mistake can cost you dearly. :(
RIP Shelley


oldrnotboldr


Mar 18, 2006, 9:28 AM
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I would also like to add that the most important piece of gear we have is ourselves. While we all do redundantly check ourselves and partners, I think it is much easier to miss something that could snowball into much larger problems very quickly.

Once again, excellent report and many thanks to all those people involved. May Shelly live on and climb on.


HappinessIsWinning


Oct 15, 2008, 10:18 AM
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Thanks, hopefully this report can help prevent this from happening to someone else.


Partner cracklover


Oct 15, 2008, 11:34 AM
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I didn't see this report the first time around.

Thanks Curt.

GO


(This post was edited by cracklover on Oct 15, 2008, 11:34 AM)


reg


Oct 29, 2008, 9:59 AM
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good job brother - of course sadness is in all our hearts for the survivors. as to your speculations, i fall in with #1. it's an easy mistake to make. visually chking should become second nature to us - don't assume. thanks - R


rasoy


Oct 29, 2008, 10:39 AM
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Accident analysis - Shelley Windsor [In reply to]
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Yep

Double checking before rappelling can be a lifesaver. Sometimes though, the stars are lined up for failure no matter who you are and how much experience you hold or what you do.

As the old saying goes ..... "When your numbers up"

You all know the rest of these buzz words


msbrenne


Dec 28, 2015, 7:45 PM
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Shelley was a good friend, a great person and we all miss her. Not a single day of climbing has gone by that she is not in my thoughts. In the weeks and months and even years following the accident I desired to be in relative privacy regarding the matter. I spoke about the events that day to her family, my close friends, and the authorities only. I believe that decision was selfish- It was what I could do at the that time- and you were all looking for answers, maybe now, still, looking for closure. In response to all the inquiry and investigation that was done and the accident analysis here is my account and observations to help provide some clarity and understanding- sorry it took a long time to respond to this thread.
There were two pieces of blue 1" tubular webbing ~15' linear, tied with water knots to make 2 individual slings. The two slings were wrapped around a large diameter single pine tree and probably girth hitched. I did not closely inspect the anchor Shelley built that day, something I always regret.
From a distance of about 25' - 30' It was apparent the slings were wrapped around the tree, and appeared to be girth hitched. Shelley tested the anchor by locking the rope in the belay device and pulling on the system with body weight before stepping over the edge of the cliff. The anchor system passed the initial weigh test. She fed slack into the system and moved towards the cliff edge. Shelley positioned, applied tension and began to rap down and then both slings slipped off the tree. Both slings were found at the bottom of the canyon connected to a locker and to the rope by a figure 8, and to Shelley by her belay device and harness.
I returned to the site again, years later, to try and reproduce the anchor failure. Using webbing similar to the kind Shelley used - it was in good used condition, with some fuzzy texture- but still within normal wear parameters. I began by girth hitching some long slings around the pine tree.
The tree is large enough in diameter that you can't reach around it. The slings have to be tossed around the tree and caught with the opposite hand, it’s a bit awkward to do. I tossed the slings around the tree many times. The fuzzy texture of the used nylon webbing sticks to the pine bark and sap a little bit like Velcro; enough that you can let go of one sling momentarily and it will stick to the tree, and hang there - on some tries and not all the time.
Using two slings of the same color it's hard to differentiate the top sling from the bottom sling. If you toss both slings around the tree they can get crossed behind the tree. Then if you accidentally girth hitch the top sling into the bottom sling and the bottom sling to the top sling and lock it with a locker there is not a secure attachment to the tree. If a force is applied to the anchor at this point it can fail, but may resist initial detachment because of friction. The friction generated from the nylon webbing crossing- one sling onto the other- behind the tree, and the pine bark, will resist a powerful tug to the anchor. This effect was not easy to reproduce but after some trial and error with a few attempts it is reproducible.
I think that is the most likely way the anchor failed, but there have been other plausible explanations.
It was a good mild weather day, we climbed three routes, and were both going to be rapping back in to have a short rest break and cool off, on the canyon floor, at our packs. I was a having a rest catching my breath near the edge of the canyon at the belay spot, where we just topped out. Shelley set off with the rope to set up the rappel for us both, she wanted to get down to her pack, take a rest, eat and drink some water, I was to follow.
Shelley had mentioned to me earlier that morning on the drive in that she had on occasion mild anemia that she treated with molasses, but just before setting up the rappel, she did not appear to be lethargic, look flush or seem ill. She was a bit anxious to get to the pack, and get to a place to urinate, but to address what has been suggested- we were not in a big rush to get down either. We were about three routes into our day and both ready for a short break but It did not look like Shelley was too fatigued from climbing to safely set up the next rappel. I will always wish that I did walk over and double check the rap system.
Always double check, and check each other, no matter how experienced you are, take care of each other, and love each other. Shelley you are loved and missed.

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