Just spoke with a DJI support person who informed me that the Terrain follow feature does not support downhill elevation lock but only uphill.  

I would like to request to please add this feature in a future update if possible for the terrain follow mode to allow the drone to descend down say a ski slope or a mountain bike hill during Terrain follow.  I was shocked that it would only support going up hill.

Obviously the user would have to pay close attention to his or her surroundings keeping clear of obvious tree's, cliffs, etc.  but a gradual downslope seems like it would make this drone absolutely revolutionary and actually how many have assumed this feature would work.

It would be nice but I can see how they would not want to have any feature that automatically descends the drone. If there was a drone that could automatically descend as it flies one would think it would be this one, though.

think just about 30mins ago, there a thread on dji beta testing..... you can sign up for the beta tester and you get to suggest this ...... hehehehhe

Under - Worry Free - Level Headed section http://www.dji.com/mavic

Their goal seems to be "and its downward facing cameras to keep you flying at the same height above the ground even as the ground moves"

Everyone will be trying to get this to work for snowboarding etc so I imagine we will see the feature expanded upon *IF* possible. + SDK for the Mavic Pro, link: DJI SDK for Mavic? (someone already intrested and posted about the elevation decrease as well)

Also note the range is from 9ft to 33ft.