I find this a strange disadvantage for an autolocker as it’s hard for me to imagine this happening very often. But now it’s twice in one year.

But, at least in this case, it didn't actually happen. Is it common for people to use Gri-gris in ice and alpine situations? Given the nature of the protection, I don't think I'd be inclined to. But what do I know?

“As someone else pointed out, if Mark had been beleaying with an autolocking device like a Reverso, he'd be dead, as the screws would have failed.

An interesting comment is the following by Dougald MacDonald


http://www.mountainproject.com/..._avalanche/106334436

“As someone else pointed out, if Mark had been beleaying with an autolocking device like a Reverso, he'd be dead, as the screws would have failed. Mark also believes that if he'd been belaying off his harness he'd be dead, because his falling partner would have pulled him into the main flow of the avalanche. As it was, he was only inches from being killed by falling debris. He was extraordinarily lucky to have survived.”

This is the second accident this year where an autolocking device, e.g., a Gri-Gri, would have caused the death or serious injury of the belayer. In the other incident at Tahquitz, the anchor failed and the belayer was knocked unconscious by the falling climber, but the belayer remained on the ledge as the climber fell past her and the rope ran through the belay device.

Is it common for people to use Gri-gris in ice and alpine situations? Given the nature of the protection, I don't think I'd be inclined to. But what do I know?

I would never use a Gri-Gri for ice, or alpine, or even multi-pitch trad routes. Ice and alpine for the protection concerns you mention above, j_ung.

This product is a belay device for the leader or second on a rope. It has been developed for indoor wall climbing or for climbing
on well-protected sport routes where anchors meet the UIAA standard. It should not be used for mountaineering or adventure climbing.

Greg,
The key is energy dissipation via (1) the rope pulling through the belay device, (2) rope stretch (having the whole rope on the stricken climber's side provides more rope to stretch) and (3) dispersion of the avalanche debris over time and distance. Think Screamer. In contrast, if the rope had locked up short without much length out to stretch, similar to what happens with a high fall factor fall, or a static line fall, most of the energy would have loaded up on the anchor, probably pushing it past the point of failure.

I'm still not buying that a full rope-length fall straight down would have a lesser impact than a smaller fall. A ten-foot fall straight on the anchor vs. a 200-foot fall straight on the anchor? It just doesn't sound right to me. But I don't know much about physics, so I'm willing to be corrected.

It's not the force from the falling climber per se, it's the force from the avalanche striking the climber, that would blow out the anchor.

So I guess what I'm hearing is that the force of the avalanche while the climber was in the avalanche zone would have pulled the anchor out if the belayor had used an autoblock-type device, but also that the avalanche somehow slowed the fall of the climber such that the full rope-length distance that he fell was not powerful enough to rip the the anchor out upon impact.

The avalanche did not slow the fall. Do you fish? Think of it like the drag setting. If a 400 lb tuna hits your 100 lb test line and you have the drag cranked down tight, the line will break or you will be pulled into the water. However, if you have the drag properly set to slip , the line will pull out from the reel and will not break immediately. The line will pull out with resistance, which hopefully will eventually exhaust the energy of the tuna before you run out of line. See the analogy?

The avalanche did not slow the fall. Do you fish? Think of it like the drag setting. If a 400 lb tuna hits your 100 lb test line and you have the drag cranked down tight, the line will break or you will be pulled into the water. However, if you have the drag properly set to slip , the line will pull out from the reel and will not break immediately. The line will pull out with resistance, which hopefully will eventually exhaust the energy of the tuna before you run out of line. See the analogy?

As the tuna pulls out line it runs out of energy.

As the avalanche falls through space, it could well be picking up more energy.