Is it best to have vision positioning on in P Mode or not?  Does it make a difference?
I know it's better to turn it off when flying over water.  I haven't flown with it yet and always fly in P mode.
Thanks in advance for any advice.

If you are asking about the P3, VPS is only of any use below 3 metres in well lit situations where the ground has a distinct surface pattern.
That's not very many situations where it will work and even less where it's useful.
May as well switch it off and forget it for most flying.

labroides@yahoo Posted at 2016-4-16 12:27
If you are asking about the P3, VPS is only of any use below 3 metres in well lit situations where t ...

Thanks.  I haven't even used it yet.  Just making sure I wasn't missing out on something.

What happens if you leave it on, even if it's not really doing any good to help, does it hurt?  I leave mine on all the time and it does just fine.  If it can use it, it does, but if not, it doesn't really do anything different.

kleake1@gmail.c Posted at 2016-4-16 14:34
What happens if you leave it on, even if it's not really doing any good to help, does it hurt?  I le ...

It shouldn't matter but in earlier firmware it would set off false alarms.
That was corrected in later versions but I've just kept it off since it's no use in the flying I do and the falase alarms when I was over the sea were scary.

I think it was primarily designed to help stability when the Phantom was flown indoors without any GPS being available.

There are so many conditions where it doesn't work correctly (read the manual) that I long ago decided to leave it off outdoors (I like skimming surfaces, fields of flowers, water, etc.). However, the VPS certainly would help indoors; if the surfaces are correct and the lighting is uniformly flat (reports of Phantoms chasing their own shadows). It might also help landing outdoors, but there's no easy way to switch it on in a hurry.
Have fun & good flying!

I just upgraded from a P3 standard to a P4. I had been flying over water a ton with no issues, but have yet to do it on the P4. Are you saying to switch to A mode on the controller for over water flight on the P4?

I fly over water often and leave VPS on.  I have flown 3ft above grass and as the elevation of the ground changes, the phantom follows.  Example: My hard has some elevation changes of about 10ft up and down.  I set the P3 at 3ft, start flying horizontally and it follows those hills and stays at 3ft.  It will do this at a surprisingly fast speed, but I haven't pushed it.  15mph or so it works great.  I don't recommend this though as it could be expensive if it doesn't work.   I haven't noticed any downfall to running VPS all of the time.