Suppose that I take off the drone from a hill which is at 500 meters from sea level.  Mavic went to a valley-like structure 1km away from take off location and the height it measures is 600 meters from the ground. The rth altitude is set to 80 meters. Will it descend down to 80 meters during RTH then fly back home maintaining that 80-meter height even if it has to climb a mountain where it took off from?

RTH height is measured from take-off height. This is height is the reference height 0.

If after take-off from that hill you fly downwards for 100 meters you will see negative height, if for one reason your craft enters a RTH procedure it will climb 180 meters.

cheers
JJB

Hi, thanks for the inquiry. Like JJB mentioned, the RTH altitude is measured from the height where the drone took off. Therefore, the aircraft would ascend depending on the RTH height setting and the height of the home-point where it took off. Hope that this would clarify your query. Thank you for your support.