Phantom avy info? 04/06/11

I'm glad everyone survived but until I learn more about Roger's injuries I'll refrain from saying glad everyone is ok. Dan mentions that he thinks will Roger will spend several months in a wheel chair - I'm really sorry to hear that.

From what I've seen a broken leg tends be a less complicated injury compared to a knee injury.

Was Roger skiing on the Fritschis? There was mention of a Fritschi binding that broke off at its toe piece.

A broken femur is a very serious injury, potentially life threatening, due to the possibility of cutting the femoral artery, painful, and necessitating a traction splint rather than a normal splint.

I'm so glad everyone is okay. Dan thanks for your account. I've always been very careful on that last little bit, thinking one day I would see it go. Like many people here, the Phantom has always been a backup plan when conditions get sketchy. That upper portion was usually avoided and laps in the trees, being careful to hang skiers right from the creek. Dan and Roger are both solid athletes and their recovery will be swift and forgotten. I can't imagine either of them will ever stop climbing, skiing or paddling just because of one epic. I too have been injured after a fall, having broken my talus bone in the Spring during a Tumwater adventure climb. Back then I took full advantage of my down time, spending time with my guitar and hitting music festivals in a cast all summer. Don't let it get you down, as this is really just an opportunity to catch up on other things you've been ignoring from this epic winter.

Aaron, yes that particular slope is fairly steep 35 plus degrees and people do routinely ski it. It has remained one of the more popular routes and is still one of my favorites. I find it deceiving because it would have to appear bad from the car or the couch for me not to give it a look so many of us go and see how conditions are in the trees for thousand feet or so before deciding it was dangerous and turning back. The deceiving part for me comes when you reach treeline. Then you are right about the toe of what they described as the deposit of their slide. When I am solo and there is that much new snow, I would probably ski down from treeline and enjoy a good tree skiing tour if I hadn't seen signs to turn me back before then. However, since it is a popular tour, one will typically find the skin track continuing up to the slot or the summit and it is tempting to continue on. This is also about the elevation that the snow pack will often change significantly from what was found in the trees. Not only is the temperature due to elevation enough of a change but it is exposed to more sun and wind and less anchors. One has to disregard what they saw in the trees and begin to evaluate it almost as a new mountain past this point and I can recall occasions that I have continued on with probably less regard than I should have perhaps because the skin track did also, or because we were in a happy place as a group and looking forward to a more full tour. I think as you get up toward the slot entrance, or actually just a little bit below it the wind slabs can throw another concern in that would not have been revealed by testing the snow earlier. I apologize if this appears as judging, it isn't meant to be. I just figured that I have seen the usual suspects on this tour for for quite awhile now and thought I would try to share what might be a typical thought pattern for some of us who could have easily made a similar error with those that might not be familiar with the tour.

Boy, Dan, that was a terrific write up and it is great of both you and Marcus to share your thoughts on this incident.

The photos show a very well-defined crown - broader than I imagined. Dan, you said that there was a noticeable layer below the new snow.

There was a slightly crusty layer about 12”-18” down representing the surface from the weekend.

And I understand that you evaluated the snow stability by feel and paying attention at switchbacks (which is normal with soft, new snow instabilities). You also said that your skiis didn't slip while climbing (which is a good guage of bond in most cases). I only have one question on this part of the situation: Did the slab fail at the crust or within an inch or two of the crust? Or did it fail in new snow wind density changes within the new snow?

Gary, these are Andy Hill's pit results, which he shared with me Thursday morning:

Avalanche Observation:
    4/6/11 – estimated occurrence at 09:30, observation at 16:00
    Mt Snoqualmie - Upper Phantom
    5,800 feet elevation, South Aspect, 30-35 degree slope angle
    Soft Slab Avalanche,
    Artificial Skier Triggered (unintentional),
    D2 force (bury/injure person),
    R4 Path Size (Large relative to how far it could have gone),
    I Bed Surface (release within new/old snow interface)
    Dry Snow Slab
    Avalanche Dimensions:
        40 – 62cm crown height
        50-75 ft crown width
        1,000+ ft vertical fall
        1,000+ ft path length

Snow properties (at Crown)
    Density of Slab (40-62 cm): Fist (dry)
    Density of bed surface: Finger/Pencil (wet)
    Shear Test: STE  (fails with min pressure)
    Shear Quality: Q1 (unusually clean, smooth, and fast)
    Compression Test CT10 (easy)
    Propagation Saw Test: End (on weak layer cut, slab slides to end)

EDIT -- I'd add that, as Andy observes, it failed at the old/new interface, but that it didn't go all the way down to the saturated crust from the earlier warm/rain events. That was another 18-24" down, I think, though I wasn't digging around up by the crown. I'll ping him and see if he has anything to add here.