 Because heli-skiing is banned across France for environmental reasons, companies offering this service only operate on the Swiss and Italian sides of the range.Since the very early days of alpine mountaineering a number of high-altitude mountain refuges have been positioned strategically across the massif to give climbers easier access to the high summits by permitting an overnight stay.The majority are owned by national mountaineering clubs, and many are wardened during the summer months, although the smaller bivouac huts are unmanned and have very basic facilities.