I’m looking for better strategies and info for doing ski tours on glaciers—without falling thru into a hidden crevasse.

The problems I’ve run into are that crevasse risk is tricky and complicated, and the careful detailed analyses of crevasse risk I’ve found so far in English are focused on alpine climbing, not skiing.

(A) Do you have a pointer to some helpful ideas or resources in English for skiers? book or web link?
French or German would also be helpful to me. (I’m open to resources in other languages, but I’d need lots of help understanding of translating them.)

(B) I tried to write down some ideas + strategies. Even though I’m not any sort of expert on crevasse risk. Here’s
my attempt on crevasse risk strategies for skiers

It’s messy and complicated. It gives more alternatives and theories than advice. Likely has several mistakes, some of them might be serious and dangerous. And it’s rather long.
If you’re looking for a sound straightforward strategy for the crevasse thing: That’s not it.

What I try to say there that I haven’t seen before:
* how crevasse risk is like avalanche risk
* red light - yellow light - green light indicators
* list of different alternative strategies, with pros + cons of each
* specific tests which could be performed out on the snow
* approaches for getting prior evidence that a crevasse zone is well-covered or not

My goal in writing it was to get somebody sufficiently irritated to go find the real expert resource (which I missed so far) about crevasse strategy for skiers, and tell me where to find it too.

Or to get one of the real experts on crevasse risk so alarmed by the misinformation, that she or he will be provoked to do the work of carefully writing the expert advice for skiers that we need. Or at least some experienced skiers will point out a couple of the more serious mistakes, and fill in some of the omissions—so I’ll know better for my own touring.

Looking forward to learning more.

Ken

That’s a long article and lots of food for thought. Knowing where the main crevasse sections are is important to avoid stopping and to ski conservatively in those areas so you don’t fall. I think you raise and interesting idea about changing your sking style to remain straighter in the fall line if not too steep, no hockey stops or stopping parallel to he general run of glaciers.

One thing I’ve started doing all the time is only to remove one ski at a time when touring, glaciers or not. I think this gets you into a good habit. The Glacier film we’ve seen also shows the snowboarder’s dilema which you mentioned too and they make the good point to never take your board off but to ask for a line. If you can’t get a line take only one foot out and carry walking poles on your sack to push.

I always assumed skiing down was safer than climbing because you are moving faster and putting less pressure at any moment on the snowpack.

Given that there are usually more deaths due to crevasse falls in your green light period: mid to late spring I assume this is down to more people being on glaciated routes at this time. There I think the refreeze must be very important. Climbing up, on an up/down tour, also gives you some opportunity to observe where the crevasses may be lurking.

davidof - 26 January 2010 09:26 AM

I always assumed skiing down was safer than climbing because you are moving faster and putting less pressure at any moment on the snowpack.

A different way of thinking of that is that with small crevasses, your speed might carry you across to safety before the bridge had time to fully collapse.

Still your body weight (plus equipment) pressed by gravity against the snow is the same whether descending or climbing.
But if you have some vertical body motion in your ski descending motion (which many of us do in softer snow), then as you’re finishing a “down” phase of the motion, you’re putting more pressure on the snow than your (quasi-static) body weight when climbing up.
If you knew where the weak spots in the snowpack were, then you could time the finish of your “up” moves to reduce the pressure. But that’s the problem of glacier skiing: it’s the crevasses you don’t know that kill you.

davidof -

Given that there are usually more deaths due to crevasse falls in your green light period: mid to late spring ...

I don’t know about that for skiers.
Have to be careful sorting out skiers versus climbers.
Though maybe my statistical sample is too small:
Like I thought the May 2009 accident with the almost-certified guide around Mont Blanc was climbing not on skis. But there were multiple skier/snowboarder accidents around Mont Blanc in February.

I guess we also need to sort out statistics between lift-accessable glaciers versus those which require substantial climbing to reach. Lift-accessible glaciers get skied lots in Febuary (esp. in France with school holidays), while climbing-accessed glaciers get skied much more in April + early May (mainly because it’s warm, but also because it’s believed to be a “green light” time?).

Ken

P.S.
(so I take it you don’t know any good resources specifically for skiers, either.)

davidof - 26 January 2010 09:26 AM

One thing I’ve started doing all the time is only to remove one ski at a time when touring, glaciers or not.

Excellent suggestion—and I like the idea of making it a general habit, not just something to try to remember on glaciers.

… changing your sking style to remain straighter in the fall line if not too steep, no hockey stops or stopping parallel to he general run of glaciers.

After further reflection and calculation ...

* making ski turns doesn’t add impact, only turns or stops with up-down motion of the upper body.

* even with typical up-down body motion in skiing soft snow, I doubt the finish of the down phase adds more than 5% pressure to the weight of the skier’s body already on the snow, by my rough calculation. (Jump-turns might add more impact).

So I doubt it’s worth modifying your skiing style much for that concern. Rather I’d suggest that if you’re thinking you’re within 5% of punching thru hidden crevasse bridges, you shouldn’t be out there at all, or you should be skiing down roped, very carefully.

* Extra impact from taking air or drops is scary. Landing from 1 meter air or drop easily adds 5 times the pressure of skier’s body weight, by my rough calculation.

* triple whammy: When skiing on a steeper slope where you have to make tighter turns to control speed, near the finish of each turn:
(1) your momementum (and your skis) tend to aimed more along the line of the crevasse, rather than across it.
(2) you tend to be imparting extra downward pressure at the finish of the downward phase of vertical upper body motion, especially if in soft snow.
(3) your traveling slower than in the middle of the turn.

So a problem with relying on speed for safety when skiing downhill is that the highest speed comes in the middle phase of the turn when you least need it.

Ken

On the point of not taking both skis off ...
http://www.chamonix.net/english/news/2009-04-13.htm

originally in French
http://www.ledauphine.com/index.jspz?chaine=23&article=119101

Ken

Amongst 12 French guides killed last season: http://pistehors.com/news/ski/comments/0922-guide-killed-crevasse-fall-mont-blanc/

Just goes to show that even experienced professionals are not immune to danger even in situations where they should have a degree of control.

The guide who was climbing when she fell into a crevasse last season was Karine Ruby, gold medal holder at snowboarding.

http://pistehors.com/news/ski/comments/0851-karine-ruby-trains-to-be-mountain-guide/

http://pistehors.com/news/ski/comments/0942-karine-ruby-killed-by-crevasse-fall/

One of the messages in the film was to probe the area you standing on to see if you are on a bridge. I remember doing a crevasse training course with Chamex and the guide kept a belay on all the time he was setting stuff up on the glacier.

davidof - 28 January 2010 09:21 AM

Just goes to show that even experienced professionals are not immune to danger even in situations where they should have a degree of control.

Part of the problem is that so much of most interesting + pretty ski touring around Mont Blanc has crevasses under it ... so it’s hard to keep your guard up all the time. And there’s other risks and problems than just crevasses to distract your focus.

Maybe a skiing robot could strike the perfect balance between making positive progress and guarding against hazard around Mont Blanc, but real humans are going to have some mis-judgments and lapses. Real human groups are also prone to certain kinds of lapses.

Strategy for planning and managing a ski tour on high glaciers has to include realistically dealing with the frailty of our own human judgment and emotion.

Just hiring a mountain guide doesn’t solve the problem of all those hidden crevasses or possible mental lapses - (that’s the evidence from sad reports in recent years) -
Though usually it helps a lot.

Ken

P.S. regarding seasonal statistics:
Surveying the public info on the web is making me suspect that lots of crevasse falls which do not result in death are not reported on the web.