May I put a word in here for Hot + High conditions. No mountains involved, just a 4500 foot long hard runway sitting in a bowl of a valley at 6500 ft.
It got a bit hot in the afternoon, around 40C.
Only just managed to clear the fence in a Cessna 150, that little trip for tea and cakes on a nice sunday afternoon taught me a lesson.
There is no special qualifications for Hot + High but density altitude has got big teeth to bite the unwary.