How would an ATC fail on rappel?

I heard a story about an ATC failing someone on a rappel. He said it failed to cinch, and his prussik failed to lock.

In my experience, if an ATC failed, I should be able to see a picture of a shattered ATC. Otherwise it was system failure caused by user failure. The story teller insists that his system was fine and his only mistake was choosing the ATC and his take away lesson was “use a different device”

I wanted to offer teaching, but he seems pretty non receptive. Maybe I’m wrong here, is there a way the system would fail if you did it textbook? 

Icy rope, used in low friction mode? Wrong diameter rope?

Dirt Kingwrote:

Icy rope, used in low friction mode? Wrong diameter rope?

Those would all be user failure though. You picked the wrong rope and set up the device wrong. (No ice) 

Prussic didnt catch? It wasnt properly dressed. 

Same goes for the atc, sounds like a pure user error. If I messed up that bad you wouldnt catch me dead reporting that incompetence. 

There is a reason the tube/plate/atc style device hasn't really changed, it works. If you used a kong gigi,  round stock attache, and a brand new double dry treated <9.6 rope would it be hard to lock off on the rappel? Maybe, but it still shouldnt outright fail 

Cesar Cardenaswrote:

Those would all be user failure though. You picked the wrong rope and set up the device wrong. (No ice) 

100% agree, but the only "mechanical" failures I can imagine off the top of my head 

LOL, sure. It  MUST be the ATC, regardless of the fact that generations of climbers have been abseiling off of them just fine in all kinds of conditions. 

Sounds like rope too thin, Prussik too thick or indeed icy rope. 

Idk, I’ve rapped off of plenty of icy ropes with a normal ATC and prusik. Yeah the prusik doesn’t catch as well but if you are rapping correctly, the ice just sheds right off when going through the ATC. Kind of soothing to watch. 

Yep.  I kept decking on rappels with an ATC.  Cleared right up when I switched to a Reverso, lol 

The guy’s a knucklehead. 

The only way I've seen this system fail is with too long of a prussic getting pushed into an ATC. Still user error but systems climbers use rarely fail to work without some user error.

Cesar Cardenaswrote:

I heard a story about an ATC failing someone on a rappel. He said it failed to cinch, and his prussik failed to lock.

Wait. What?  And he’s still alive to tell about. No injuries?  Doesn’t sound like a failure to me.  

I've detailed some common rappelling failure mechanisms in the white paper linked below that might be worthwhile reading for your acquaintance, even if they don't want to discuss it openly. I'm betting it had something to do with the friction hitch, skinny ropes, and/or panic grab.

http://staff.weber.edu/derekdebruin/research/rappelling.pdf

The story teller insists that his system was fine and his only mistake was choosing the ATC and his take away lesson was “use a different device”

99%+ chance it’s user error and if that’s his takeaway the guy is a danger to himself and others. 

Lesson 1; puff puff pass or partake AFTER descending safely.  

If he was still holding the brake strand then how could the system fail? 

Michael Hallwrote:

If he was still holding the brake strand then how could the system fail? 

These days, we’re trained to do otherwise as required by gyms: must use brake-assisted devices.  Our reflexes assume brake assist.

If that's the case then again, goes back to user error. Inadequate training on equipment being used. 

User error versus systematic error: choose your poison.

Or set yourself up for what you think fits best. There is no mandate here.

Here is a recent example of how a rappel system can fail (of course, the system involves the user):

http://publications.americanalpineclub.org/articles/13201215612.pdf

Cesar Cardenaswrote:

I heard a story about an ATC failing someone on a rappel. He said it failed to cinch, and his prussik failed to lock.

In my experience, if an ATC failed, I should be able to see a picture of a shattered ATC. Otherwise it was system failure caused by user failure. The story teller insists that his system was fine and his only mistake was choosing the ATC and his take away lesson was “use a different device”

I wanted to offer teaching, but he seems pretty non receptive. Maybe I’m wrong here, is there a way the system would fail if you did it textbook? 

Let him use any device that's not an ATC and regale you with another rappelling tale, then report back here so that we may speculate further with new information.

They did not provide enough information on how it was set up and how it failed. So there isn't much we can really provide here.

There are numerous failure modes. Most likely it was user error, thinking it was set up properly, but it was not.

I would guess that there was an error somewhere between the harness and the helmet. Unclear where exactly though, needs more information.