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11/19/17, 09:37 AM

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Author Topic: January 8, 2017, Snoqualmie Pass  (Read 1557 times)
silaswild
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January 8, 2017, Snoqualmie Pass
« on: 01/08/17, 04:11 PM »

Slightly slabby conditions as we approached open SW slopes above 4500' made us head for shelter. 8" fluff in the trees among a few bombs 5000-3000'.  Thanks ts.
« Last Edit: 01/08/17, 10:39 PM by silaswild » Logged
Charlie Hagedorn
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Re: January 8, 2017, Snoqualmie Pass
« Reply #1 on: 01/08/17, 05:56 PM »

A few thoughts to add - yesterday's surface hoar in sheltered locations below treeline was buried intact by today's storm. As expected, the new snow came in warmer and more dense than what lies below.

'Slightly-slabby' refers to instabilities at the surface, probably confined to the new snow and new windslab from today's winds. The deepest slabs that moved for us were <10 cm thick and limited in spatial extent to ~3m in size. We flirted near the edge of instability, but were very mindful of limiting potential consequence, avoiding large start zones of any kind.

Biggest lesson from the day: Before we entered committing avalanche terrain at higher elevation, we did a beacon check. One of the beacons in the party, which had worked at the car, no longer functioned, presumably due to the cold. New batteries brought us back to normal, and we were on our way.
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ErikT
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Re: January 8, 2017, Snoqualmie Pass
« Reply #2 on: 01/09/17, 09:00 AM »


Biggest lesson from the day: Before we entered committing avalanche terrain at higher elevation, we did a beacon check. One of the beacons in the party, which had worked at the car, no longer functioned, presumably due to the cold. New batteries brought us back to normal, and we were on our way.

Whoah, nicely done. Do you recall the % of that beacon's battery at the beginning of the tour? Hopefully it was close to marginal already... I want to think you can develop a foolproof test at the beginning to avoid this. Perhaps a lower tolerance for lower % at the beginning of a tour if it's cold. Out on a limb... the types of batteries beacons call (alkalines) have a more linear falloff of voltage over their life compared to Li-ion. I wonder how temperature effects performance... linear, or a drop-off at some point.

an interesting item to note, for particular mammut beacons: http://www.mammutavalanchesafety.com/2012/12/alkaline-vs-lithium-batteries.html

Thanks for bringing this thought up, and sorry for some thread drift... always bite on some nerding.
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kamtron
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Re: January 8, 2017, Snoqualmie Pass
« Reply #3 on: 01/09/17, 09:54 AM »

Best/least wind-destroyed snow we found was below 4500' and on SW-SE aspects, although the NW facing runs to Snow Lake were holding up too.
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Charlie Hagedorn
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Re: January 8, 2017, Snoqualmie Pass
« Reply #4 on: 01/09/17, 10:50 AM »

Do you recall the % of that beacon's battery at the beginning of the tour?

I don't; we didn't do a formal beacon check at the beginning of the tour. It was judged sufficient by both of us at the car to have heard the startup beep from the beacon in question, a now-obvious oversight.

In response to your question, I just checked the batteries we removed from the dead beacon. At the time of the test, the storage room was +12C, plus whatever heat entered the batteries from my hands. I don't have the original beacon (a BCA Tracker), but putting them into an old Pieps DSP with a numerical battery readout shows 00% (and starts up with a happy beep). I suspect that the batteries were nearly dead at the start, and the cold did them in.

It is most unsettling to know that we might have traveled beyond the point where we noted the dead beacon. In a party of two, it doesn't matter whose beacon is kaput if a rescue is required. Even a battery change would consume far too much time.

I'm grateful for the 'free lesson', even for something already addressed perfectly by the AIARE curriculum. I'm hopeful that by sharing our experience, someone else might benefit.

In addition, I'll forward this thread over to a beacon manufacturer; there's little reason not to have an audio warning at startup of a low battery, followed by a periodic low-battery chirp (think annoying smoke-detector) when the batteries are nearly depleted.
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Lowell_Skoog
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Re: January 8, 2017, Snoqualmie Pass
« Reply #5 on: 01/09/17, 11:00 AM »

I'm wondering, was the beacon worn under any clothing layers, or outside of all clothing layers?

It might not make any difference with a battery as low as it sounds like this was. But it seems like wearing the beacon underneath some layers would keep the batteries warmer in general and might be a reasonable thing to do as a general practice.

I typically wear my beacon under a soft shell with a full length zipper, which makes it easy to access the beacon when you need to. I wouldn't wear it under a layer that couldn't be opened with a zipper.
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Charlie Hagedorn
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Re: January 8, 2017, Snoqualmie Pass
« Reply #6 on: 01/09/17, 11:11 AM »

It was under a bunch of layers (not sure how many), but the batteries were cold to the touch during the battery change.

I'm particularly surprised that the beacon failed to send, even on cold batteries. After the 12/18/07 Edith Creek accident, I put a running Pieps DSP in the freezer and checked it approximately daily. The beacon continued to transmit long after the display had died, long after reaching 0%.

Receiving, on the other hand, requires far more current from the batteries. It's quite possible that we could have wound up in a state where the beacon barely transmitted, but couldn't receive.
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