Control range > Video range?

[ElGuano]

Sorry, re-reading your comment below, I see you were talking about rising terrain above your take-off point, not flying at absolute "mountainous" altitude. If mountains are the concern though, I imagine you'll have clear GPS signal and not have to worry about ATTI limits.

Remember that the FAA voluntary safety standard of 400' is measured AGL (above the ground), so the limit set for the Inspire 1 needs to be adjustable to a barometric altitude much higher in order for flight in mountainous terrain to be possible.

 

[slim.slamma]

It's already been established that outside of a restricted fly zone, you can already set your height limit (or not) as you wish, so you can do exactly as you describe (and all current DJI FCs use baro and height limits the same way so this isn't new or unique to the Inspire). But to be clear on the technical details, the barometer is NOT set to ASL (nor can it reasonably be) as suggested above.

Intresting