Hello,
i am thinking what will happen if i will get to the top of mountain (for example 400m height). Set up phantom's homepoint , take off for 10 meters and fly away (side way) from the top of mountain. What Altitude(height) will be shown at the screen of DJI GO ?  -10m or -410m?

Thanks.

It will show 10 Metres. The height is measured with respect to the take off point. If you then fly down 30 Metres into the valley, it will show -20 Metres.

Geebax Posted at 2016-2-26 10:38
It will show 10 Metres. The height is measured with respect to the take off point. If you then fly d ...

Thanks for prompt answer.
There is another question regarding previous one:

Ok, let it be -20 metres after i fly down the valley. But then if i will press auto landing , does Phantom will land safely while it will have -20metres in his "brains" ?

Thanks

If you press rth button,  Phantom will ascend to rth height and go home.  If rth is set to 30 meters,  Phantom will climb to 30 meters above home point.  Even if you are -50 meters below.  But,  are you talking about auto land or return to home?  There is a difference.  Auto land is not the same as return to home.  

You need to set you're return to home setting in you're controller... Your phantom will behave in Several ways.

1) If the aircraft is higher then you're preset Altitude when it enters RTH... It will Not desend. It will fly to you're RTH location and then descend.

2) if the aircraft is below you're pre-set RTH altitude it will ascend to your preset altitude first  fly to the RTH location and then descend.

3rd party software and pre-detrimined setting will make the bird do different things

1) if you have it set to do so.. it might just hover and wait for RC signal..if signal is not regained, and  if the battery dies....

This is not a plug and play device.... spend some time carefully experimenting in a  controlled environment..

Have fun and fly safe

Kneepuck Posted at 2016-2-26 11:12
If you press rth button,  Phantom will ascend to rth height and go home.  If rth is set to 30 meters ...

I were talking about auto-land (not RTH).
But RTH in this case is also interesting  -  ok realise we started at the top of the hill (100m height). I've setup homepoint , takeoff , get up for 10 metres and fly away from the hill .
Now real distance between phantom and ground is 100+10=110metres. Phantom's DJI GO will show 10 , because as Geebax mentioned - the height is measured with respect to the take off point.

Ok, then i press auto land, phantom stard to decrease his height and after 10metres going down the app will show 0metres , -1metres ,  -5metres and so on. So my question is - will the aircraft land normally if it detects that it's altitude is negative?

AlaskanTides Posted at 2016-2-26 11:18
You need to set you're return to home setting in you're controller... Your phantom will behave in Se ...

Thanks for useful tips!

Well,  to be honest,  I have never used the auto land feature.  But the manual says to initiate auto-land and then follow the instructions on the screen.  I am going to go out on a limb and say that the instructions will probably say for you to navigate to the area above where you want to land and then press ok,  or some such.  The Phantom will complete the landing the same way it knows to shut the motors down when you have full stick down.  It knows,  because despite the command to descend,  it is unable to descend further because it is on the ground.  After a couple seconds of that,  it turns off the motors.  To put it more simply,  when you press auto land,  it begins landing straight down from where it is,  until it can descend no further.  Not the same as an rth at all.  The altitude displayed on the screen is really just a reference for our convenience,  especially as far as negative numbers goes,  if you see what I mean.  Yes,  the Phantom uses the barometer to limit height above the home point,  but it does not care if you are lower.  It also does not care if you take off ,  as I do, climb to 10 feet above home point  and immediately fly out over a canyon that is a couple of thousand feet deep.  It still thinks you are at  10 feet above the home point.


**** Additional edit****

Now that I think about it,  I have landed manually 30 feet below my home point with no problem.


  

Michalas Posted at 2016-2-26 20:43
I were talking about auto-land (not RTH).
But RTH in this case is also interesting  -  ok realise  ...

"So my question is - will the aircraft land normally if it detects that it's altitude is negative?"
There's nothing special about negative altitude.
It just means you are lower than where you took off.
You wouldn't be the first person to fly from a cliff, mountain or high point.
Your Phantom has no way of knowing how far the ground is below it.

Cool, now it's clear.
Thanks guys for the info!