As Height Changes From Cliff to Valley

[eyesinthesky]

I have a question that refers to operating a drone over a cliff. There are a few scenic overlooks where I would like to take some videos, not only from the vantage point of the overlook, but also from out over the valley, looking back at the people on the overlook.
My concern is - what happens to the drone when it goes beyond the edge of the cliff where the overlook is located? Meaning, if the floor of the valley is a couple of hundred feet below the top of the cliff where the overlook is located, will the drone descend according to the new floor?
i.e., could it conceivably descend below the height of the overlook and not be able to be brought back up to that height again?

 

[RodPad]

The Phantoms use a Barometer for elevation, It doesn't use AGL.
It won't be a factor.

I hope, I'm not missing something

Rod ..

 

[eyesinthesky]

Rod,

Thank you for the response. I wasn't thinking about barometric pressure. I was worried about AGL.

Al

 

[captainmilehigh]

Just be sure you have your RTH altitude set high enough to clear anything between you and the drone for the entire flight due to unexpected
loss of signal when behind hills, or down in lower valley terrain.

Most of us have had issues with 'Phantom Magnet Trees' that didn't end well.

 

[Meta4]

My concern is - what happens to the drone when it goes beyond the edge of the cliff where the overlook is located?

The same thing that happens when a plane or a bird flies over a valley.
Your drone is a flying machine, not a following terrain machine.
Your drone has no way to tell whether the ground below is 10 feet below or 10,000 feet below.
It matters not whether the relative height is positive or negative.

 

[Meta4]

Just be sure you have your RTH altitude set high enough to clear anything between you and the drone for the entire flight due to unexpected
loss of signal when behind hills, or down in lower valley terrain.

Even if the RTH height was set to the minimum, on loss of signal the drone is still going to ascend to the set height above the launch point before coming home.

 

[captainmilehigh]

Even if the RTH height was set to the minimum, on loss of signal the drone is still going to ascend to the set height above the launch point before coming home.

Hopefully the OP knows that, and sets the RTH altitude high enough to clear obstacles on the return flight path.

 

[eyesinthesky]

The same thing that happens when a plane or a bird flies over a valley.
Your drone is a flying machine, not a following terrain machine.
Your drone has no way to tell whether the ground below is 10 feet below or 10,000 feet below.
It matters not whether the relative height is positive or negative.

That was what I was unsure about. Thank you for your explanation.

 

[eyesinthesky]

Even if the RTH height was set to the minimum, on loss of signal the drone is still going to ascend to the set height above the launch point before coming home.

Hopefully, there won't be a loss of signal, but you never know.

 

[nahacar]

Drones don’t “follow” the ground level automatically. They measure height relative to the takeoff point using a barometer, not the terrain below. So when you fly out over a cliff, the drone will stay at the same altitude relative to where you launched, even if the valley drops hundreds of feet beneath it.

 

[Harleydude]

Everyone is correct so far regarding manual flight. But if you program waypoints, make sure your software doesn't download SRTM data (AKA; "terrain follow'). Some software will reveal a terrain profile before flight. But some doesn't. I'm not sure if any of the DJI offerings offer this feature, as I always used 3rd-party waypoint programs. Buyer beware.

D

 

[crash1sttime]

will the drone descend according to the new floor?

The zero height is the take off point, going over a cliff and down will result in a negative height reading, so flying down 200ft will result in a -200ft, once RTH kicks in it will ascend to zero then continue to the height set in the app