FATMAP difficulty grade
When you ski down the Mt-Lachaux slope, just before the steep part you should cut to the right.
There is an open first 'steep' part, to get into an open forest.
Crossing Chemin des Dames piste, on the right of Amadeus 2006 restaurant, you'll find a path through the forest to arrive at Cabane de Mattia.
In front there is a ski lift where you need to walk for 20 m and, following the ski lift line to the right, you then cut to the left where you will find a chain, normally covered with snow, but where you need to be careful, and then a barrier.
Go through the forest to get to the Kodak piste.
Follow it until you see the old middle station of a lift.
Before that turn left, and get to an open forest.
It's possible you'll get to Chemin de Montana slope, but if you keep a bit to the left you won't cross it until the very end.