I think you are talking about Megeve or Salanche as they are the nearest altiports to chmonix. Iflew out of Megeve last may and it is something every pilot must do once!!! But you cant just pitch up there as you need an Alpine rating(about 5 hrs ) with a french instructor, i drove there and whent up in the club Jodel,a 180hp four seater. Happy landings and let me know if you go.