It occurs to me to wonder, because, really, I'm not a physicist ... ... er ... ah .. right. Anyway: How much "more difficult" is it to parachute to a precise spot if your target is a mile above sea level, as compared to sea level? They just ran an advert for the military, including the drops to sports arenas. Mile High Stadium? The CLink? A difference of about a mile. The one is literally a mile up; the other is about forty or fifty feet above sea level.
The thinner air would make for faster speed and therefore a more difficult landing unless they used larger parachutes at higher altitude.
