RTH Question, sorry if it's a repeat

[Pegasus Robin]

Hi all, I have a question regarding RTH. I'm wondering about differences in hight and how it affects it. For instance, I have my RTH set at 30 meters and it works just great at the moment. I live by the sea so I've only tested it on sea level. I live in an area surrounded by mountains and I want to take my Phantom on hikes and launch from varying elevation points. So! My main questions is;
If I launch from the base of a mountain, then I fly up to higher than the set RTH limit, will the drone try to drop to the 30 meters set at base (and crash into the mountain) or would it use its barometer and figure out how high it is according to the surroundings and then raise 30 meters more according to the new level? (There are lots of trees on the mountains near where I live)
Any information you can give me will be great
Cheers
Robin

 

[msinger]

If I launch from the base of a mountain, then I fly up to higher than the set RTH limit, will the drone try to drop to the 30 meters set at base

No. When RTH is initiated, the Phantom will never descend before returning to the home point.

 

[Pegasus Robin]

Cool! So it would raise to its 30m set point from its position and then come home? Would it lower its position as it flew home? Say for instance I was flying 120 meters up and I initiated return home and I'm at sea level, would it keep the hight until base or slowly descend?

 

[Meta4]

would it use its barometer and figure out how high it is according to the surroundings and then raise 30 meters more according to the new level?

RTH height is relative to your launch spot so you have to choose a suitable RTH height that will clear any trees etc that might be between where you launch and where you fly to.
If the Phantom is higher than RTH level, it would come home at the higher level.

 

[Richard R]

And remember, on RTH, the bird will return in a straight line. So make sure that it's higher than anything that might be between it and the home point.

 

[msinger]

So it would raise to its 30m set point from its position and then come home?

The RTH altitude is always the height above the takeoff point. When RTH is initiated, your Phantom will ascend to 30m if DJI GO is showing the altitude is currently below 30m. If DJI GO is showing the current altitude is above 30m, then your Phantom will immediately start flying to the home point.

Would it lower its position as it flew home?

No. It will not descend until it's directly over top of the home point.

 

[Pegasus Robin]

RTH height is relative to your launch spot so you have to choose a suitable RTH height that will clear any trees etc that might be between where you launch and where you fly to.
If the Phantom is higher than RTH level, it would come home at the higher level.

I think that's answered my question, thanks. So let me get this straight. I'm above the trees flying 120 meters up the mountain and I'm stood at sea level. I initiate the RTH and the drone will fly back and land?

 

[msinger]

Your Phantom does not understand sea level. It only keeps track of how far it ascends/descends above/below the takeoff point.

 

[Pegasus Robin]

The RTH altitude is always the height above the takeoff point. When RTH is initiated, your Phantom will ascend to 30m if DJI GO is showing the altitude is currently below 30m. If DJI GO is showing the current altitude is above 30m, then your Phantom will immediately start flying to the home point.


No. It will not descend until it's directly over top of the home point.

That's awesome! Just what I needed to know! Thanks

 

[Meta4]

I think that's answered my question, thanks. So let me get this straight. I'm above the trees flying 120 meters up the mountain and I'm stood at sea level. I initiate the RTH and the drone will fly back and land?

If the Phantom is already higher (above launch pointt) than your RTH setting, it will come straight home before descending.
It will never descend until it is directly above home point.

 

[Pegasus Robin]

And remember, on RTH, the bird will return in a straight line. So make sure that it's higher than anything that might be between it and the home point.

Totally. Looking out for pylons and such

 

[Pegasus Robin]

Thanks everyone for clearing that up. I've flown quads for years, APM and Pixhawk and I never used a RTH on any of them. It's only since I got my P3P that I've tested it with confidence and I wanted to make sure that what I was doing was correct