And then there is obstacle clearance. Over any terrain with appreciable elevation differences, topographic features can easily rule out otherwise eligible airf

And then there is obstacle clearance. Over any terrain with appreciable elevation differences, topographic features can easily rule out otherwise eligible airfields because you'll have to cross granite on the glide down. /Acey I left that off before but it begged mentioning since it's a question that asks for a real answer/confirmation if starting from jet cruise altitudes. If you are starting at FL410, you could easily head down a box canyon accidentally when the Alps, Pyrenees, Rockies, etc. are nearby.