I have a Phantom 4 Adv.
I have reset the reset Distance parameters to their Maximum.
I'm flying the AC way out in the open desert away from anything, so there are no obsticals.

My question is:
When in TapFly Mode,
How far will the A/C go, before it stops and returns to home, relative to the available battery level...?

Example:
Lets assume that the present battery level it at 100% when the A/C is set on course in TapFly,
It's traveling in a straight line relative to the Home Point when the battery level reaches 50%,...

Q:
Does the A/C immediately STOP and Return to the Home Point, since it has exhausted 50% of its battery supply...?
-OR-
Does it continue until the Battery Level reaches 20% before returning to the Home Point.

I've not attempted to test this because I don't want to lose the A/C in the process.

As long as you don't turn smart return home off, it should always kick into RTH when it senses it only has enough battery to get back home, no matter what mode you use.

Aloha Steve,

     Along with what fansb1 posted, I use TapFly in the mountains by my house, so I can actually go up in altitude.  My aircraft will climb in altitude until they reach 1640 feet (500 meters) and then stop.  The stopping is a good benefit and I use it regularly now.  While it is in TapFly, I can set my camera or record the surrounding scenery knowing that TapFly will not fly my aircraft into a mountain ridge.  Sometimes I walk to a different location so trees (I live in a jungle) will not block my signal.  Then on the return, I can use the same tool to walk back to my HomePoint.

     In your case, it sounds like you are flying over a flat desert.  Even if you are flying over a hilly desert, you can set your MAX Altitude to as high as you want.  The FAA limits consumer drone altitudes to 400 feet above ground level or a structure.  If I want to fly over the ocean, I can set the MAX Altitude to 100 or higher feet up to 400 feet and TapFly up to that altitude where the aircraft will stop.  Of course the idea here is to not TapFly past the 50% mark.

     Well, this was a nice distraction.  As fansb1 posted, Smart RTH will stop your P4 and turn around to Return to Home.  The RTH algorithm tries to account for headwinds, so it errs on the side of a safe flight from which you can return.  You may land with more than 30% battery depending on the winds and other factors.

     Hope this helps!

Aloha and Drone On!

Hi. I appreciate your time bringing this topic to us. In regards to your concern, we have 3 types of RTH (Return to Home). They are Smart RTH, Low battery RTH and Failsafe RTH. In your case, RTH will only trigger once low battery level prompt to your app. For more information please kindly read the Phantom 4 Advanced Manual on our website and go to page 15. Should you have further question, please let us know. Thanks for your support.