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stymingersfink
Sep 12, 2008, 9:38 PM
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knieveltech wrote: majid_sabet wrote: a leader falling some 50+ feet of distance passing his belayer will not generate an FF2. not with 50 feet of dynamic rope in service taking some of the load however, a belayer falling off his anchor with 2-3 feet of static link could generate a great amount of forces. How much well , we just have to wait for Rgold to come up with numbers. You're a fucking moron Majid. Take a reading comprehension class or something. It is ENTIRELY possible to generate forces exceeding FF2 when the fall is on static material, which is a distinct possibility given the description of the leader's meatbomb directly onto the belay/anchor. In closing, and as stated previously, you're a fucking moron. Have a nice day.
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stymingersfink
Sep 12, 2008, 9:41 PM
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stymingersfink wrote: knieveltech wrote: majid_sabet wrote: a leader falling some 50+ feet of distance passing his belayer will not generate an FF2. not with 50 feet of dynamic rope in service taking some of the load however, a belayer falling off his anchor with 2-3 feet of static link could generate a great amount of forces. How much well , we just have to wait for Rgold to come up with numbers. You're a fucking moron Majid. Take a reading comprehension class or something. It is ENTIRELY possible to generate forces exceeding FF2 when the fall is on static material, which is a distinct possibility given the description of the leader's meatbomb directly onto the belay/anchor. In closing, and as stated previously, you're a fucking moron. Have a nice day. I think that since FF's are a measure of force on a dynamic rope, I'm unsure whether it can be applied as a measure of force in a static system. Anyone more reliable than majidiot got an opinion on this?
Am I talkin' sense here?
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knieveltech
Sep 12, 2008, 9:43 PM
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stymingersfink wrote: knieveltech wrote: majid_sabet wrote: a leader falling some 50+ feet of distance passing his belayer will not generate an FF2. not with 50 feet of dynamic rope in service taking some of the load however, a belayer falling off his anchor with 2-3 feet of static link could generate a great amount of forces. How much well , we just have to wait for Rgold to come up with numbers. You're a fucking moron Majid. Take a reading comprehension class or something. It is ENTIRELY possible to generate forces exceeding FF2 when the fall is on static material, which is a distinct possibility given the description of the leader's meatbomb directly onto the belay/anchor. In closing, and as stated previously, you're a fucking moron. Have a nice day. I think that since FF's are a measure of force on a dynamic rope, I'm unsure whether it can be applied as a measure of force in a static system. Anyone more reliable than majidiot got an opinion on this?
You make a perfectly valid point. At best the term could be used as shorthand for the theoretical maximum possible fall force experienced by an anchor that's part of a dynamic system (which IIRC is supposed to be somewhere in the neighborhood of 10kn depending on who you believe). Mostly I just wanted to call Majid a fucking moron. Carry on.
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sungam
Sep 12, 2008, 9:45 PM
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stymingersfink wrote: stymingersfink wrote: knieveltech wrote: majid_sabet wrote: a leader falling some 50+ feet of distance passing his belayer will not generate an FF2. not with 50 feet of dynamic rope in service taking some of the load however, a belayer falling off his anchor with 2-3 feet of static link could generate a great amount of forces. How much well , we just have to wait for Rgold to come up with numbers. You're a fucking moron Majid. Take a reading comprehension class or something. It is ENTIRELY possible to generate forces exceeding FF2 when the fall is on static material, which is a distinct possibility given the description of the leader's meatbomb directly onto the belay/anchor. In closing, and as stated previously, you're a fucking moron. Have a nice day. I think that since FF's are a measure of force on a dynamic rope, I'm unsure whether it can be applied as a measure of force in a static system. Anyone more reliable than majidiot got an opinion on this? ...in fact, i would be willing to bet that had the anchor not failed, and the belayer not been knocked unconscious, the true FF on the anchor had the fall been arrested, would actually come out lower than a FF2, since a portion of the falls energy had ben consumed in the arresting forces which caused the top cam to fail. Am I talkin' sense here?
The fall factor, as a variable in an equation, is defined as the force generated in a fall divided by the force absorbed by the dynamicy in the system.
The fall factor for any loading on a static system is infinite - but don't confuse fall factor with force, fall factor is just a variable that effects the force exerted on a given anchor.
The failing cam, depending how good it was, could have taken out anything from 0.0001% to 99.99% of the force of the fall. if 99.99% was taken out by the cam, the FF would be far lower then 2, and probably lower then 1.
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stymingersfink
Sep 12, 2008, 9:50 PM
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knieveltech wrote: stymingersfink wrote: knieveltech wrote: majid_sabet wrote: a leader falling some 50+ feet of distance passing his belayer will not generate an FF2. not with 50 feet of dynamic rope in service taking some of the load however, a belayer falling off his anchor with 2-3 feet of static link could generate a great amount of forces. How much well , we just have to wait for Rgold to come up with numbers. You're a fucking moron Majid. Take a reading comprehension class or something. It is ENTIRELY possible to generate forces exceeding FF2 when the fall is on static material, which is a distinct possibility given the description of the leader's meatbomb directly onto the belay/anchor. In closing, and as stated previously, you're a fucking moron. Have a nice day. I think that since FF's are a measure of force on a dynamic rope, I'm unsure whether it can be applied as a measure of force in a static system. Anyone more reliable than majidiot got an opinion on this? You make a perfectly valid point. At best the term could be used as shorthand for the theoretical maximum possible fall force experienced by an anchor that's part of a dynamic system (which IIRC is supposed to be somewhere in the neighborhood of 10kn depending on who you believe). Mostly I just wanted to call Majid a fucking moron. Carry on.
yes, majidiot is s fucking moron, so your point was valid. Unfortunately when you quote him, I have to look at his drivel as well. Otherwise, his continued non-presence in my browser window is a testament to the brilliance of jt's killfile script. 
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trenchdigger
Sep 12, 2008, 9:59 PM
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knieveltech wrote: majid_sabet wrote: a leader falling some 50+ feet of distance passing his belayer will not generate an FF2. not with 50 feet of dynamic rope in service taking some of the load however, a belayer falling off his anchor with 2-3 feet of static link could generate a great amount of forces. How much well , we just have to wait for Rgold to come up with numbers. You're a fucking moron Majid. Take a reading comprehension class or something. It is ENTIRELY possible to generate forces exceeding FF2 when the fall is on static material, which is a distinct possibility given the description of the leader's meatbomb directly onto the belay/anchor. In closing, and as stated previously, you're a fucking moron. Have a nice day.
We're losing track of the original thread here, but it's worth pointing out that fall factor is independent of the type of material ("static" or "dynamic") involved. The resultant peak forces are not. For example, a FF1 fall on dynamic rope is far less severe than a FF1 fall on static rope.
More on fall factor from the good 'ol wikipedia
Back to the point...
Figuring out just how much force gets transferred to the anchor when a leader falls onto the belayer will be nearly impossible to determine. The human body is a non-rigid, soft, irregularly shaped structure which makes collision energy transfer especially difficult to predict. If you considered the worst case scenario (perfect, 1-dimensional energy transfer) onto a belayer with no slack between them and the anchor, you could estimate the peak force using the standard equations (ie. petzl calculator) with a couple of modifications:
fall factor = the length of the fall (from high point to impact with belayer) / length of rope between the belayer and the anchor
rope material = the type of material the belayer is using to connect to the anchor
You can see that it wouldn't be hard to exceed the equivalent of a FF2 considering the worst case scenario.
On average, how much of the leader's fall energy would be transferred to the belayer? Who knows. Anyone want to volunteer to be test subjects?
(This post was edited by trenchdigger on Sep 12, 2008, 10:07 PM)
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crotch
Sep 12, 2008, 10:35 PM
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trenchdigger
Sep 12, 2008, 10:43 PM
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crotch wrote: trenchdigger wrote: Back to the point... Figuring out just how much force gets transferred to the anchor when a leader falls onto the belayer will be nearly impossible to determine. [snip] On average, how much of the leader's fall energy would be transferred to the belayer? Who knows. Anyone want to volunteer to be test subjects? Exactly! There is no such thing as an "average" fall onto a belayer and I doubt it would be practical to build anchors designed to withstand such an event. The take home lesson for me is to arrange my belay stations, when possible, so that I'm not directly under the leader.
I couldn't agree more.
I'd still like to find some volunteers to do some testing though. Anyone? Anyone???
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sungam
Sep 12, 2008, 11:01 PM
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trenchdigger wrote: crotch wrote: trenchdigger wrote: Back to the point... Figuring out just how much force gets transferred to the anchor when a leader falls onto the belayer will be nearly impossible to determine. [snip] On average, how much of the leader's fall energy would be transferred to the belayer? Who knows. Anyone want to volunteer to be test subjects? Exactly! There is no such thing as an "average" fall onto a belayer and I doubt it would be practical to build anchors designed to withstand such an event. The take home lesson for me is to arrange my belay stations, when possible, so that I'm not directly under the leader. I couldn't agree more. I'd still like to find some volunteers to do some testing though. Anyone? Anyone???
Someone jumps and I catch them from like 10 feet, right? and let them slip by?
Let's do it on bolts with a tensile-o-meter going straight from the bolts to my harness, with a dynamic rope backing it up.
Of course, the give in the detector will slightly effect the measurement, but that should be negligible.
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trenchdigger
Sep 12, 2008, 11:26 PM
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sungam wrote: You got the force measuring gear, I'm all for it! Someone jumps and I catch them from like 10 feet, right? and let them slip by? Let's do it on bolts with a tensile-o-meter going straight from the bolts to my harness, with a dynamic rope backing it up. Of course, the give in the detector will slightly effect the measurement, but that should be negligible.
We'll have to try a variety of configurations... head-first falls, feet-first, etc. And for alpine considerations, we should probably do some with ice tools and crampons.
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sungam
Sep 12, 2008, 11:33 PM
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trenchdigger wrote: sungam wrote: You got the force measuring gear, I'm all for it! Someone jumps and I catch them from like 10 feet, right? and let them slip by? Let's do it on bolts with a tensile-o-meter going straight from the bolts to my harness, with a dynamic rope backing it up. Of course, the give in the detector will slightly effect the measurement, but that should be negligible. We'll have to try a variety of configurations... head-first falls, feet-first, etc. And for alpine considerations, we should probably do some with ice tools and crampons.
I was serious. Get some 150pounder to jump on me and I will make the catch. If anyone has tension measuring kit, that is.
Back on topic, though, did the rain start pre or post fall?
Perhaps the leader ran it out
a)cuz it was easy, but then it got wet and slippy
b)wanted to hurry and beat the rain.
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jt512
Sep 12, 2008, 11:54 PM
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stymingersfink wrote: knieveltech wrote: majid_sabet wrote: a leader falling some 50+ feet of distance passing his belayer will not generate an FF2. not with 50 feet of dynamic rope in service taking some of the load however, a belayer falling off his anchor with 2-3 feet of static link could generate a great amount of forces. How much well , we just have to wait for Rgold to come up with numbers. You're a fucking moron Majid. Take a reading comprehension class or something. It is ENTIRELY possible to generate forces exceeding FF2 when the fall is on static material, which is a distinct possibility given the description of the leader's meatbomb directly onto the belay/anchor. In closing, and as stated previously, you're a fucking moron. Have a nice day. I think that since FF's are a measure of force on a dynamic rope, I'm unsure whether it can be applied as a measure of force in a static system. Anyone more reliable than majidiot got an opinion on this?
My opinion is that you are correct.
Fall factor is a relevant concept in climbing because, theoretically, falls of equal fall factor have equal peak forces, even for falls of different length; that is, after the fall factor is taken into account, neither the distance fallen nor the amount of rope out affect the peak force. If this were not the case, then there would be little point in talking about fall factor at all.
The fact that once the fall factor is considered that fall length and amount of rope out are irrelevant wrt peak force -- if I have correctly interpreted information that rgold has presented -- is because dynamic ropes behave approximately like idealized (Hooke's Law) springs. However, rgold once mentioned in a post that less elastic materials, like low-elongation ropes and slings, do not approximately obey Hooke's Law. Therefore, I suspect, that falls of different lengths but equal fall factors taken on such inelastic materials would have different peak forces. Thus, applying the concept of fall factor to falls onto relatively inelastic materials would have little utility.
If anyone wants to discuss this further, then maybe they should start a new thread.
Jay
(This post was edited by jt512 on Sep 12, 2008, 11:56 PM)
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rgold
Sep 13, 2008, 12:37 AM
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My name has come up a few times now in relation to getting some numbers to explain the anchor load. I'm sorry, but this situation is too weird for the kind of very elementary theoretical analysis that is pretty much all we are capable of. I don't think there is going to be any clear resolution of the various mysteries surrounding this almost unbelievable combination of tragedy and good luck.
I have been arguing for a long time now that there are no statistics on belay anchor reliability and, experienced or not, there are almost no climbers who have had the kind of experiences that would qualify them to make accurate judgements of an anchor's reliability. We are pretty much all just guessing, and my personal opinion is that there are quite a few anchors out there, including ones that follow all the "rules," that won't stand up to a big climbing impact. It's just that they are very rarely tested.
The Suicide accident has a number of very unusual features. It is the only accident I've heard about in which the belay anchor failed and the belayer wasn't pulled off, and I think this is a significant fact. We can hypothesize various scenarios for how this can happen, but I think they all have to incorporate the basic fact that the leader somehow knocked out the anchor (or what was left of it) when he hit the belayer. I say this for two reasons:
1. If the load of a falling leader came on a locked off belayer and caused anchor extraction, it is almost inconceivable that the belayer wouldn't have sailed off the ledge.
2. If the belayer was stunned or knocked out and was not in control of the belay, then it is almost inconceivable that the anchor would be extracted by a load so tiny it didn't pull the belayer off.
This leaves the anchor extraction to whatever transpired at the moment the falling leader hit the belayer. It is possible, depending on the orientation of the pieces, that the nut had already lifted out from upward belayer motion before the protection nut pulled, and that the remaining single cam was somehow kicked out at impact. Or perhaps both pieces had already failed because of belayer lift. We'll never know, but I don't think some force calculation, no matter how impressive, will expain what happened here.
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cracklover
Sep 13, 2008, 12:51 AM
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rgold wrote: the leader somehow knocked out the anchor (or what was left of it) when he hit the belayer. I say this for two reasons: 1. If the load of a falling leader came on a locked off belayer and caused anchor extraction, it is almost inconceivable that the belayer wouldn't have sailed off the ledge. 2. If the belayer was stunned or knocked out and was not in control of the belay, then it is almost inconceivable that the anchor would be extracted by a load so tiny it didn't pull the belayer off.
Exactly what I was thinking. Thanks for articulating it so clearly.
I hope both parties have a full and a speedy recovery.
And major major kudos to those involved in the rescue. Those conditions sound absolutely horendous.
GO
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moose_droppings
Sep 13, 2008, 2:32 AM
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from ST post wrote: Trevor placed a #1 BD cam and proceeded to climb above it. He complained of some difficulties with the climbing and suddenly pitched off backwards. He came tight to the #1 which he was roughly 5 feet above. The cam pulled and he continued falling backward, now head-first, toward the belay. Claire locked off the rope through her ATC and braced inward against the wall to arrest the fall. Trevor hit Claire causing her to slam into the wall leading to fractures of her cheek bone, arm and wrist. Claire also was knocked unconscious at this point. Trevor continued his fall and as the rope came tight through the anchor, the two pieces failed. Luckily for Claire, she had collapsed onto the ledge when she passed out. Her unconscious state also led to a relaxed grip on the rope. Thus, as Trevor continued falling, Claire remained on the ledge despite the anchor blowing. Had she not been knocked out, she would have certainly kept a tight hold on the brake and undoubtedly would have been pulled off the ledge into a fall with Trevor. Sadly, under these circumstances, there was virtually nothing that would have kept Trevor from decking but Claire somehow escaped the same fate.
If their recollection is correct, I have trouble believing falling 5 foot above the #1 cam, and then it pulling, could have lifted the belayer enough to pull pieces of the anchor up and out. I would tend to agree with the assumption that the leader knocked out the belay when he struck the belayer who was tied to it directly. Her being knocked out released her grip on the rope and allowed the rope to run through the device while he continued to fall.
Someone above posted that all this is premature and without enough known facts to continue to speculate. I hope that some of this speculation will help guide the investigation into some of these theories so that all avenues are looked at openly.
Edit: I too would like to wish a speedy and full recovery to both climbers.
(This post was edited by moose_droppings on Sep 13, 2008, 3:02 AM)
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teacherman
Sep 13, 2008, 3:07 AM
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I just discovered this thread, and my prayers go out to the injured climbers for their full and rapid recovery. Having taken the AMGA SPI course just last weekend, safety is a big topic in my mind right now. A main point stressed in the course is the importance of individual judgment in assessing and managing the risks of each situation. That said, a few questions come to mind.
1) Is there a guidebook that lists gear requirements for this route? Knowing what gear to carry allows for more efficient and effective pro.
2) Do these climbers have friends/mentors more experienced than they, who might have known they were preparing to tackle this route, and who could have offered advice or notes of caution? Climbers are, in my experience, a superb community of people, and I have benefited from the experience of many people who coaxed me along and encouraged me. So, I wonder if any of their fellow gymmies could have seen the risks on this one. Not a finger-point, just a thought that comes to mind. I am alive due to a #2 Camalot I placed at the direction of a very knowledgeable Quebecois named Matthieu, who was kind enough to take me up a great crack at Squamish a few years back. I found out a cam will hit you in the forehead if not placed properly, while a good placement will hold quite a fall......
3) Hoping to become a guide myself someday, I'm anal about just one thing in my life, climbing safety. One accident can be enough to ruin a guide. SO, my safety officer hails straight from the
"Department of Redundancy Department." Not knowing the route, but suspecting that the belay point was sketchy at best, had I attempted this route, you would hear my hexes, etc. clanking in the next county, I'd have brought so much stuff. People laugh at pieces placed a few feet apart, but living to climb again is good............
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majid_sabet
Sep 13, 2008, 3:20 AM
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knieveltech wrote: majid_sabet wrote: a leader falling some 50+ feet of distance passing his belayer will not generate an FF2. not with 50 feet of dynamic rope in service taking some of the load however, a belayer falling off his anchor with 2-3 feet of static link could generate a great amount of forces. How much well , we just have to wait for Rgold to come up with numbers. You're a fucking moron Majid. Take a reading comprehension class or something. It is ENTIRELY possible to generate forces exceeding FF2 when the fall is on static material, which is a distinct possibility given the description of the leader's meatbomb directly onto the belay/anchor. In closing, and as stated previously, you're a fucking moron. Have a nice day.
Fuck you too but we are not dealing static material so back original incident where one climber fell on dynamic material with over 50 feet of rope in service.
have nice evening
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858jason
Sep 13, 2008, 3:22 AM
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sungam wrote: Back on topic, though, did the rain start pre or post fall? Perhaps the leader ran it out a)cuz it was easy, but then it got wet and slippy b)wanted to hurry and beat the rain.
When I was hiking in that day there was a light rain that lasted a few minutes, the rain may have been heavier and lasted longer higher up. My party and I got to the North Face maybe 45 minutes later. I think that was when I started hearing the helicopter. One of my party was at the tree on Flower of High Rank when the heavy rain and hail started.
Based on response times, it seems probable they were climbing during that initial rain.
It's been said before, but the two that got Claire down did an amazing job under horrible conditions. The hail and water coming down the rock face was incredible.
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billl7
Sep 13, 2008, 3:32 AM
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Llama relayed there was about 20 feet between the belay and the 1st piece of pro. And the leader was 5 feet above that. 0.4 FF. This site, http://www.getbeta.com/fall_factor.asp, calculates 5.2 kN of force. Seems high to me but it probably peaks and drops quickly.
I believe that is peak force on the belayer/anchor (edit: this is incorrect; see later post). The peak force on the one piece up pitch 2 was considerably greater than 5.2 kN. And 5.2 kN is enough to lift the belayer - how much is hard to say.
(can someone double check that 5.2 kN peak force to the belayer/anchor?)
Trevor falls and rope comes tight on the top piece. Claire is lifted enough to at least tweak/rotate the anchor pieces (possible?). Maybe neither anchor piece was set for upward pull given that the route seemed runout to the leader. The combined resistance of Claire and the compromised anchor pieces causes the one piece placed on lead to pull/tweak/twist/break out.
Trevor falls on Claire and the two anchor pieces are jerked back down causing them to pull out, or maybe the nut was already out, or some other variation. Anyway, Claire loses consciousness and Trevor falls through the first pitch.
edit: I assumed 170 pounds for Trevor.
(This post was edited by billl7 on Sep 13, 2008, 4:57 AM)
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sungam
Sep 13, 2008, 3:50 AM
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here's another possibility-
The belayer is feeding out rope when the leader falls, this causes
A) a slightly larger fall, giving a slighty more violent jerk upwards
2)Her left hand, with her arm still at full length from feeding the rope upwards, pushes the nut up and out of it's placement.
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billl7
Sep 13, 2008, 3:56 AM
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Anything that introduces rope into the system would raise the fall factor - good point, Sungam. (much later edit: the OP later points out that this does not apply when the non-slack-fall-factor is already greater than 1; in such cases, adding slack reduces the fall factor towards 1; however, this is not the case based on currently available information on this accident)
I've taken around 10 lead falls. On a couple there was more slack in the system than I expected, once because I misguided my belayer on the amount of slack I wanted and once because the rope sagged through some horizontal stretches. Both times I lifted my belayer. Both times the distance from the belayer to the highest piece was 20 feet and greater. Both times I was around 5 feet above my highest piece.
(This post was edited by billl7 on Sep 14, 2008, 4:37 PM)
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sungam
Sep 13, 2008, 4:05 AM
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not to mention the weight difference.
Imagine a 220 guy taking a fall on a 130 chick, that chick is going flying.
If the chick hit the gear (I've lifted a belayer so his ATC was tight on my first draw) she could have weakened it or even pulled in 90% out, then trevor hits her on the way down and finishes the job while knocking her flat down onto the ledge, breaking her arm and cheek (rite?).
A possibility.
I feel like Hercule Poirot.
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billl7
Sep 13, 2008, 4:16 AM
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Not bad for a couple of weekend warriors - eh (assuming a second-check on the force calc confirms the possibility)?
(This post was edited by billl7 on Sep 13, 2008, 4:25 AM)
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moose_droppings
Sep 13, 2008, 4:31 AM
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billl7 wrote: Anything that introduces rope into the system would raise the fall factor
More rope introduced into the system will decrease the FF.
The .4FF and 5.2kn you calculated above is the force applied to the #1 cam. The belayers share of that would be closer to 2kn.
Isn't this right?
(This post was edited by moose_droppings on Sep 13, 2008, 4:31 AM)
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billl7
Sep 13, 2008, 4:37 AM
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Maybe I'm rusty - thanks for checking me. As for the FF ...
FF = length of fall / amount of rope out
Assume 5 feet of slack.
FF = (10+5) / (25+5) = 0.5
Without slack it was 0.4.
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