Revelstoke Avy fatality - heli guide operation

[Foggy_Goggles]

I'd like the know the alpha angle. I use that shit all the time when figuring out safe zone.

[spook]

i'd use the alpha angle and add a bunch. i'm a slow runner.

[theshredder]

I think the most overlooked is weather system change. this yr in particular its been a major factor. if you skier trigger something you may just rip out a pocket. with a huge weather system and subsequent rapid temp elevation the potential for a huge area to rip out exists this yr. we all make our decisions early and are aware of the factors of daytime heat because of the sun but its not quite as apparent if the vis is the same but temp rockets up with a system. it seems like a lot of fluctuations this yr with the jet stream ripping down from the north cooling some areas more than normal. it'd almost be useful to have some sort of warning alarm indicating rapid temp spike. just a thought. by the way 45 is much ot young. vibes.

ya but then youre relying on weather models. garbage in garbage out. the snowpack reacts instantly to factors that are hard to measure directly like thermal radiation. Even in the absence of a major change like surface air temperature, direct sunlight, or winds, a change in upper level temperature or clouds could cause a subtle reorientation of forces within the snowpack and destabilize it. There is only anecdotal evidence that this is the case, and I don't think that will change soon, but I think its much harder to disprove that possibility than to prove it. and unfortunately that leaves you with only your intuition, if you're paying attention, since your body and nervous system will react to suble changes too. like an increase in sweating, or external factors you can pick up like more frequent tree bombs or snow melting on dark surfaces etc.. might be good to bring a solar/infrared pyranometer and watch for spikes, particularly in years like this where the chances are very low but the consequences are very high. just to be sure.

[icelanticskier]

Alpha angle=opening yer eyes and knowing what yer looking at. Wide birth works also

rog

[icelanticskier]

A guide? How bout yer everyday joe? Joey can't call it alpha angle? Better chance for not becoming a statistic if you call it something else?

rog

[grinch]

ya but then youre relying on weather models. garbage in garbage out. the snowpack reacts instantly to factors that are hard to measure directly like thermal radiation. Even in the absence of a major change like surface air temperature, direct sunlight, or winds, a change in upper level temperature or clouds could cause a subtle reorientation of forces within the snowpack and destabilize it. There is only anecdotal evidence that this is the case, and I don't think that will change soon, but I think its much harder to disprove that possibility than to prove it. and unfortunately that leaves you with only your intuition, if you're paying attention, since your body and nervous system will react to suble changes too. like an increase in sweating, or external factors you can pick up like more frequent tree bombs or snow melting on dark surfaces etc.. might be good to bring a solar/infrared pyranometer and watch for spikes, particularly in years like this where the chances are very low but the consequences are very high. just to be sure.

Yes of course. All that. I forgot tree bombs etc. it's just that atleast a few of these incidents happened during changing weather systems like this incident. It was the start if a warming trend. I was thinking we put a lot of faith in our assessments in the morning then our intuition as the day progresses but when you're sweating climbing a mt or in a heli it's not always as apparent that temp has shot up. I won't pretend to know how heli ops reassess as the day progresses in regards to co policy but I think it's something that seems to catch people. Even if your not involved in an incident. We've all found ourselves a little late cresting a baking south face to drop on the other side. Combine that with a warm front ripping in and the huge consequences we have this yr it could be that straw that broke the camels back. Traveling in the BC is like playing your best poker hand in certain situation and an rapid temp alarm could be of help it seems. A wake up call. 12-2pm isn't always were the biggest temp spike happens. Like I say, just a thought. An incident hit a little closer to home this yr and took out a friend and great guy.

[icelanticskier]

Your own skin and having to unzip yer coat or take off layers should tell most any bc traveler a tale or two about the days weather/temp changes.

rog

[grinch]

Oh right. The obvious. Nobody ever forgets that. 12-2 stats son

[icelanticskier]

Oh right. The obvious. Nobody ever forgets that. 12-2 stats son

the obvious kills, son.

rog

[grinch]

Nice . I was trying to suggest temp spikes not necessarily warm temps but rapid heating or in some cases cooling. This yr a lot of these aren't sluffs that build to weight overload and step down but rather sudden whole slope collapse on buried basal layers running long and fast. Temp spikes. The spikes man the spikes

[icelanticskier]

unusual wx creates unusual avalanches. this has been an unusual year for many regions. so why are so many getting caught off guard when increased guard should be up? voodoo.........

rog

[grinch]

/anxiouslyawaitsinvestigation

[icelanticskier]

oui

rog

[totaliboard]

alpha angle is the route a guide takes to cut a slope, whether right or wrong.

ah.. no.

[jamesp]

Most, if not all, people would consider themselves in a safe spot if the hazard was Mod/Con & they were behind a 150m x 250m patch of big trees. Have to put this down to WTF / bad luck.

I heard some more info re this, 3rd hand so take it with a grain of salt.
Apparently there were 2 (or 3? can't remember) groups in the basin, skied the run multiple times before it slid. Group 1 (ie the group hit) just arrived at an upper pick-up. They were hit by the air blast not debris, & were all sent flying many meters through the air. Guy who died was thrown further down a gully (?) & triggered (?) & ended up buried ~1000m further down the mountain. They had chainsaws digging him out as there were so many trees etc buried with him
Meanwhile Group 2 was at a lower pick-up in the same basin, heli was there loading & took off in a hurry (doors open, half loaded) to avoid being hit by the slide &/blast. Debris flowed either side of Group 2's pick-up point which was on a rise, they were un-harmed.

Still sounds very WTF, & definitely sounds like it could have been much much worse.

No snow nerd reports of alpha angle or percolation

[Shadam]

how many lines, bowls terrain did this heli op stay away from this season ???

how few lines did they have left ???

hard to make money eh?

[kootenayskier]

Our group of 17 was enjoying a day of bluebird powder skiing at Fairy Meadows (also in the Adamants) that day. http://kootenayskier.files.wordpress...pg?w=500&h=375 Heard an unusual amount of heli traffic in the distance. From my perspective, stability on anything North-ish was bomber, with big lines being skied all week, while obvious instabilities persisted on South-ish aspects. Part of our group backed off from a SE slope that morning after digging. By midday, in perfect windless, cloudless conditions, it had warmed to the point of small wet slides initiating on steep rocky south faces. Just saying that on or below a huge SW facing roll-over is not where any of us chose to be at that time.