Hi,
I have a quick question for you. It happened to me to take-off from let's say 400m above sea level (on a hill).

Dracula's Castle in the Valley, Bran, Romania

I did a compas calibration before flight and went on near that castle in the background (Dracula's supposed castle in Bran, Romania). I've raised the drone (DJI Phantom 3pro) at about 7m and went ahead in the vally where the ground was clearly lower than 7m from my takeoff point.

I lowered the drone and saw in the app I was getting close to 0 m (though I was still high in the sky). I got scared and stoped, raised it back to higher altitude. I was affraid that the drone if it will detect 0m will consider that it landed and stop the engines.

Dracula's Castle in the Valley, Bran, Romania

What happens if you go under your take-off altitude? Anyone has any idea?

Thanks,
Alin Popescu
http://www.aeriALL.ro

The drone will not stop when the altitude becomes 0 m  . It will keep going down if you control the RC to do this .  By the way , nice picture !

DJI-Patrick Posted at 2016-1-5 15:03
The drone will not stop when the altitude become 0 m  . It will keep going down if you control the R ...

Good to know, thanks.
I'm an engineer by formation and 0 is a dangerous number for me and IT systems :p. This is why I was afraid :p

Thanks for appreciation for the photo ;)

Even in RTH, it will know it is at a 'negative' altitude, and still climb to the prescribed height above its home point before returning home. I was worried about that too. When you're on a mountain, it's hard NOT to fly below your take off point sometimes. And yes! Nice pics.  Happy Flying!

Barney.

Barney Rubbel Posted at 2016-1-5 15:29
Even in RTH, it will know it is at a 'negative' altitude, and still climb to the prescribed height a ...

Thanks Barney for clearing this out. Exactly the mountain flights were making me nervous!

I also took off from a hill side the other day and spent most of the flight below 0 feet and fortunately it was fine and didn't fall out the sky ;)