Rognon du Plan - Le fil à plomb
Interesting route, especially early in the season. The gully is not particularly sustained. Three technical pitches. However, the position is superb throughout.
Approach
From the Plan de l’Aiguille, go up the Glacier des Pèlerins on the true right bank, usually tracked if the conditions have been good for a few days. Make your way up to the crevassed zone just below the bergschrund. Use snowbridges and then overcome the bergschrund where practicable.
Route
Go up the long, steep, snowy couloir (50-55°) to the first ice pitch on the left. Climb this technical pitch and traverse to the left to the belay. By a short passage of mixed, go up several metres to rejoin the line of the gully. Variant, (harder): It is possibile to go straight up by a thin, steep runnel of ice slanting to the right.
Continue by two easier pitches (70° max) until the foot of the obvious “ice corner”. The crux pitch, 40m at 85°. The ice is sometimes thin, but mostly good. (If the ice is bad, there is a possibility to make a rising traverse to the left by mixed climbing on good rock, 1 peg, to get back to the ice.) Above, the next two pitches again have some fairly technical sections. After this it is usually mainly snow and not too difficult, though long, (but beautiful!). One escapes by a slanting gully leading to the Midi-Plan ridge, close to the Rognon du Plan. Reach the Aiguille du Midi by this classic ridge. (When you are tired, it seems to be a long way!)
Descent
Midi-Plan ridge then the cable car.
Faces due north, does not get the sun, except for the ridge and the last 150m of gully, (exposed to sluffs in warm weather, where the angle eases.)
700m of difficulties, without counting the approach and especially the return to the Aig du Midi.

The text and images in this page are available
under a Creative Commons CC-by-sa licence.