Brevent is the main launch point to fly the Chamonix valley, served by cable car to within 70 meters. 2 directions of launch are available. The “house thermal” trigger point is right in front of launch. Initially valley winds will get you going. On several occasions I’ve had over 1000fpm climb here, this can be quite rough with parts of the canopy collapsing, hence I fly the Nova Phantom, performance on a B class wing. It was here I got to over 10,000ft.