One of the classic Chamonix ski descents! Steep, sustained, scary/rocky/exposed entrance usually done by rappel. In previous times considered an extreme skiing venture, by today's insane Chamonix standards it is now getting tracked out by lunchtime and has even been known to see moguls!
This is not to say it should be undertaken lightly - a shaky turn on the top half of this 45 degree, 800m long, fairly sustained slope has a high probabilty of leading to a helicopter being involved. It is, as well, often highly avalanche prone. Do not forget that even a small slide will likely send you flying head over heals, where plenty of small rock bands and twists and turns in the couloir await to break your fall.
Chamonix skiers are nowadays completely bonkers, taking far too much risk. Evaluate the safety of this route on your own
versus following the tracks that will certainly already be there. Keep in mind this route, like all others of the similar grade, are never
completely free from objective danger (avalanches, rocks under the snow surface, etc.)
Not to be missed!
If you have to break a trail on this one, you either 1) really REALLY know what you're doing 2) are really REALLY nuts (e.g. there is extremely high avo danger or you are trying it at the wrong time of year) or 3) you have taken the first Midi lift up after a storm and are really REALLY lucky to be the first in (doubtful!). But here's the route from start to finish anyway:
Take the Midi up climb down the arete, bearing as high as possible skier's right around the Midi South Face. Keep as high right as you can and find the entrance to the indistinct couloir in between the Abri Simond and Cosmiques refuges.
A rappel entrance is usual as the top is very steep and rocky. Most people use a very old, rusty cable as an anchor but you may want to bring and leave behind a long cord as "community service." A double 45m rap got us to a place we could sideslip in March 2006, but this varies dramatically from year to year.
The top section is around 50 degrees, quickly mellowing out to around 45 degrees for a long middle section, and gradually getting less steep, but never less than around 40 degrees. You are in a "no fall zone" for around 400m (i.e. a fall here could be deadly).
Once on the Bossons Glaciar, book it as fast as you can out of the obvious (and very serious) serac danger zone, hugging the cliffs on the skier's right. This zone is sometimes a jolly ski, sometimes a messy, hair-rasing glacial mess requiring you to rope together and sometimes downclimb using crampons and an axe. Bring the whole kit on this one.
Keep traversing back towards the Plan du L'Aiguille midstation bearing high skier's right. Do not dilly-dally in this obvious avalanche-prone area. Depending on snow conditions and who built the track, you will probably need to climb slightly, usually with skis still on, side-slipping upwards, to get above a cliff band.
Near the old midstation of the predecesor to the Aiguille du Midi cablecar, you can either keep on a high and very much "uphill" traverse to reach the Midi midstation, or continue all the way down to the Tunnel du Mont Blanc. Be sure to check out the snow conditions and be advised that it's very steep in parts and route finding down there is a whole other mess in itself - consult a guidebook and study it in advance.
If you elect to take the whole shebang down to Cham', you'll end up at the tunnel entrance. From there you can walk across the parking lot and continue down to the Midi base station via a much less steep path through the forest. You end up right in the Midi car park, so why not do the Glaciar Rond on the next bin up?
Bring the whole kit for a glaciar ski trip - rope (2x45m), crevass rescue gear, etc.
LinksTR: Couloir des Cosmiques 06.03.14
- trip report and more photos at the TGR Forums. Warning: contains possibly offensive language