Gear Failure on West Face Leaning Tower results in whipper.

Russ Walling wrote: 2 hour lead is nothing. On those 6 hour leads I'd put the rope under my head and pull out a few feet of slack. They pull on the rope, it jerks on my head, I wake up and they never see me sleeping. I'd also put a Jumar down the line a few feet from the belay as a third hand... well, the only hand if If I'm sleeping. This was using a Fig. 8 rig or an ATC. .

Haha, I originally was going to say a 3 hour lead but I didn't want to be accused of exaggerating on the internet. I can't even imagine a 6 hour lead, I could drain an Ipod battery watching movies in that kind of time.

I like the rope under the head trick, it could avoid my partner getting mad from having to repeatedly tug on the gri-gri to wake me up.

First off, glad to hear you guys are OK!!!

And then a couple of comments. :)

If you are looking for things to improve, I'd start with at least this one:

QUOTE: "All of my trad draws are composed of Mammut wire gates for the gear side, Mammut dyneema shoulder slings and the Mammut bent gates."

Why have the wire gates on the gear side of the trad draws? As said several times earlier, wire gates are much less prone to gate flutter (smaller mass on the gate makes it a lot less likely to move do to sudden forces on the biner). Personally, I always have a wire gate on the rope side, where the potential for gate flutter exist.

Here in Europe half ropes are a lot more frequently used also for rock climbing and they really do generate smaller forces on the gear (handy for sketchy winter gear, but maybe also when avoiding breaking biners). Single ropes >10mm usually have a UIAA impact force of >8kN and for <8.5mm half ropes this force is usually <5kN.

Also, I would not dismiss the increase in impact force caused by the grigri as trivial. Check the following from beal (sure there is movement even using a grigri as the belayer is pulled upwards, but still, pretty significant differences):

impact forces for atc vs grigri

So, would using wire gates in the rope en end of the quick draws, climbing with half ropes and belaying with an atc have prevented the huge whipper? Maybe not, especially if the biners broke due to some twisting forces. But using wire gates and taking various measures to reduce impact forces shouldn't be a bad idea either.

Ps. Still, for two biners to break no matter the above mentioned is amazingly bad luck (one can sure be open due to gate flutter, but TWO?!?), which begs the question of them being somehow weakened beforehand... either by micro-fractures or manufacturing mistakes... both of which again sound amazingly unlikely, when talking about well kept gear from a reliable brand, such as Mammut.

After reviewing the added picture of the fractured surface, the angle of the fracture, some examples from my "Failure Analysis of Engineering Materials" book, and the BD blog listed above . . . my mildly educated SWAG would be failure due to torsional stress with the gate closed that started at a notch as one person mentioned from clipping to a bolt or other similar damage.

Please take this with a grain of salt as I am only looking at pictures, reading, and reviewing. I did not sleep at a "Holiday Inn Express" last night either, but I was a reliability engineer in a processing plant for a few years and had to make similar analyses. Usually, though, most of my failures were from either chemicals or improper installation/use.

About the actual failure mechanisms, the thing that seems the most inexplicable to me is that the cam pulled out but the bent gate biner for its sling was missing. Any damage to the cam lobes?

That's a cool graph, Joel. Comparing it to the other reference I mentioned ...

Geir Hundal (see Myth #7), saw forces multiply with the gri-gri by ~1.88 and ~1.14 for FF 0.25 and 0.5. (I suspect the more realistic friction adjustment of Jay T's model explains the smaller multiplication at higher FF but am not sure.)

It appears in the Beal data that the rope with 9.0 kN impact force sees a ~1.34 multiplication of forces which is between the two data points in Geir's test.

And so the two test seem consistent although more detail from both tests is needed to make a complete comparison.

JoelO wrote:Here in Europe half ropes are a lot more frequently used also for rock climbing and they really do generate smaller forces on the gear (handy for sketchy winter gear, but maybe also when avoiding breaking biners). Single ropes >10mm usually have a UIAA impact force of >8kN and for <8.5mm half ropes this force is usually <5kN.

The impact force ratings for half and single ropes aren´t comparable as the test is different, a dual rated rope like a Sterling Fusion gets 8.5kN as a single strand and 6.4kN as a half rope.

Also...this is an aid climb, pretty much nobody is using half ropes for aid climbing.

Not saying everyone should start to use half ropes, especially for aid-climbs, but there is a point in minimizing impact fores and half-ropes is one way to go, even in climbs where you have one or two odd aid pitches, if the rest is free climbing.

But anyway... this is getting on a tangent. I think the important thing here is just to recognize that impact force is a factor to be taken into account when considering the overall safety of one's system, especially on long routes with varying rock and gear quality. And one way to allow more flexibility there (pun not intended!) is to use half ropes (they stretch more and often you can place pieces so that they share the load when coming to a crux).

" Also--Anthony found the .5 c4 and draw minus the bent gate hung up on one of his aiders by some kind of luck. It was not clipped to it--it was tangled in it and he found it after the fall when he went to set up to jug. So on the way down, we figure his aider hooked the cam and pulled it as well."

You two probably have the best guess as to what happened with this gear. At the same time, I have seen gear pull during a lead fall. It shoots out of the rock and it generally fires off in the direction of the fallen leader. It wouldn't be surprising if the aiders did not snag it and pull it out during the fall but rather - after the piece pulled - acted like a big net that caught the piece with its sling.

Or not.

Hopefully someone checks this ... Using * Jay T's Impact Force Calculator
All that said, Jay's force calculator is of course theoretical. I haven't read what assumptions he makes about things like a somewhat upwardly mobile belayer.

These are the two threads that went into creation of the calculators. Look for posts between QTM and JT.

Quick discussion about the calc
rockclimbing.com/cgi-bin/fo…

Original thread.
rockclimbing.com/cgi-bin/fo…

Torsional forces? On a rope-end biner that is floating in a sewn sling, not straight into a hanger? Just not seeing the mechanism there for any real torsion without the biner somehow being pinned.

Seems a little curious that 9/10 biner breaking stories I've read were all Mammut biners. Those Moses superlight wiregates were blowing up left and right a few years ago.

I'd chalk the whole deal up to freaky anomaly...but I also wouldn't be climbing on Mammut biners anytime soon either.

I'm saying a little Occam's razor mixed with Murphy's law...what could of went wrong did go wrong, and why?...really bad luck. You guys should have doubled down on black that day instead. The good news...a situation like this probably won't happen again for at least 30-40 years so we're all in the clear thanks for getting it out of the way for everyone else. Kind of like two commercial jets haven't crashed in the same week, month, year or whatever.

Glad you guys are ok. Did anyone go up and check the integrity of the bolts afterward. I know they're rated to elephant strength but given the string of events who knows?

Were there any batch numbers visible on the failed biners?

agree with willS, not seeing what will act as a reaction force to the torsion, as a sling has very little torsional stiffness.

also, interesting point about the mammut biners. that was my first thought also - seems like a LOT of broken biner reports i have read were mammuts, particularly moses, which unfortunately i have a bunch of....

Ah yes sorry about the bogus falling force calculator... I didn't know it was messed up. But it's crazy yet good that they would have the FF messed up (I think this crossed my mind but figured who would create a faulty calculator), if they didn't, it would be difficult to verify the kN force is also unreliable.

So many factors go into a real life situation. I have an engineering degree but when my classmate totaled his Corvette, we tried to calculate how fast he was going, or the friction of the road surface, or something, and the number came out to be completely unrealistic. So it was then we realized that the physics equations (sometimes you learn the simplified equations only to learn there are additional parts of the equation, e.g. E=mc^2 is only part of it, and the other parts "cancel" in a particular situation) often don't apply to real life where there are so many other factors involved.

Hi everyone,

I'm Anthony, the climber who took the fall.

So I just want to clarify some issues and write up what I remember from the fall:

Gear:
If I recall correctly, I think there were actually 4 pieces between me and Shern before I fell. From top to bottom:
1. Purple C4
2. A marginal small nut (either a BD #4/5 or a DMM Peenut.)
3. A good nut (BD #7 I think)
4. The bolt
They were all extended with trad draws with dyneema slings, the Mammut wire gates (for gear side), and Mammut bent gates (rope end.)

The fall:
The nut that I was standing on popped right when I fifi'ed into the piece. Before I knew it, I was flying past Shern. Funny thing is, the fall happened so quick that I didn't even have the time to think about "oh shit it's over" or something (I'm sure Shern would probably think differently watching me falling onto the belay.) The fall felt like one single whip; I don't remember the pieces slowing me down much.

Some observations:
After I fell, the only pieces of gear still attached to the lead line were the rope-end biner from the C4 and the small nut (still attached to a draw) which got ripped out. The C4 (with sling) was found hanging on one of my aiders, not clipped to anything. The good nut (with sling) and the bolt (with sling) were still on the wall. The rope-end biners for both pieces were missing. One of them (the broken one) was later found by the party behind us.

Some other info:
- The rope was a 3-yo heavily used Mammut (yes another Mammut product!) Flash 10.5mm. According to this website , the impact force is 9.0kN.
- I'm 125lb. Aid gear is probably another 10lb.
- It can't be the static rope; the other end of the haul line wasn't on belay.
- We didn't use those rubber bands on our draws (who uses them on trad draws anyway?!)
- The pitch is diagonal (to the left) and about vertical.

Analysis:
Just like what Shern said, we think the rope-end biner from the C4 unclipped itself from the sling, and my aider proceeded to catch on the piece and rip it off. I then ripped out the marginal piece, and broke the biners on the lower two pieces.

I have thought hard and talked to a lot of people about this. The force generated from the fall can be particularly high due to the use of 1) an old, fat, stiff rope, 2) belaying with Grigri. Using an ATC might reduce the peak force, but of course, whether the belayer would be able to catch a huge whipper with an ATC would be a whole other story.

Just like many of you have suggested, comparing the broken biner with the BD QC lab report , it seems like the biners might be broken due to open gate failure, possibly due to gate fluttering, especially since they are solid gates. Or it might be broken due to some torsional forces.

Needless to say, Shern and I both felt extremely lucky that we walked away practically unharmed---if we were on something less overhanging, we would have been in big troubles.

Be safe out there.

Dang, man, glad you both are well.

Make sure all this information, and the broken biner, gets back to Mammute!

" Also--Anthony found the .5 c4 and draw minus the bent gate hung up on one of his aiders by some kind of luck. It was not clipped to it--it was tangled in it and he found it after the fall when he went to set up to jug. So on the way down, we figure his aider hooked the cam and pulled it as well."

Only thing that has come to mind for this is along the lines that you suggested ...

During the fall, aider snags on cam somehow and somewhere above the rope side biner (caught on cam trigger?). Cam gets pulled out of crack (high forces since rope is not involved). But the rope-side biner is slotted in a crack. Anthony's momentum pulls the draw across the bent gate and unclips it. Cam and sling remain tangled in the aiders. The draw's bent gate is eventually pulled free of the crack and is left free-floating on the rope. Any deep score marks on that free-floating biner?

And the above two unlikely things (snag plus bentgate slotted in crack just so) are followed by a third: gate flutter on bent gate associated with the bolt lower down.

And the above doesn't touch on why the rope-side biner of the lower nut failed (assuming that was not the nut Anthony weighted in the first place). Gate flutter again? Or also slotted just so in the crack?

Bizzare.

JLP wrote: For those who don't know what Mohr's Circle is and why the break has an angle to it, feel free to offer up other explainations on how ~1-2000 lbs of force (~open gate rating) went un-noticed by a 120 lb climber...

I qualify. :-)

My understanding is that breakage of gear / rock can occur which absorbs very little energy and so slows the climber down very little. In other words, the force to break something can be enough to cause failure but is quasi-independent of the actual energy absorbed from whatever applied the force.

A rope that stretches to failure is a great example of absorbing a lot of energy before breakage. A quick karate chop to a stack of bricks absorbs far less energy from the hand than more slowly pressing down on the bricks until they break.

Caprinae monkey wrote: ... (sometimes you learn the simplified equations only to learn there are additional parts of the equation, e.g. E=mc^2 is only part of it, and the other parts "cancel" in a particular situation) often don't apply to real life where there are so many other factors involved.

The force calculators are based on RG's "Standard Equation for Impact Force". If you're an engineer, you might enjoy the read!

rockclimbing.com/cgi-bin/fo…;postatt_id=746

But yes, there are a lot of other factors that the calculators cannot take into account. The calculator gives a simple number which may be ballpark, but could be way off.

I tried to bring this in upthread but it got lost in the frenzy...

And again while I have a mechanically adept mind I am no mathmetician, so I'll do the best I can.

As I read it, RG's paper deals with the impact force of a falling climber as if that climber were tied off to the gear which catches him - as if the rope from that gear to the belayer added no force to the gear.

My understanding is that the force of the falling climber and the force generated, coming from the other side other gear, by the belayer holding the fall are additive.