been researching on wifi and cellular ipads and couldn't pass up the $349 deal on ipad air 2..  I know you can use the ipad wifi version just fine while flying.
my question is if im not in a wifi area with no cell phone with gps around me i cannot use RTH and Maps?  However using the iphone 6 with hotspot on will be able to use RTH and maps?  so confusing...  

The Maps and RTH works off of the GPS on the Phantom.  Your Home Point will be set while you are on the ground and have adequate GPS signal for the Phantom (not your phone or iPad Air).  When the home point is set you will see it on the map.  You can track yourself on the map (as long as you cached it before hand when you had wifi service).   You can RTH if you need to as it will return to the Home Point that was set previously.    But if you walk around or move you will not be able to reset your home point to your new position because you don't have GPS on your device connected to the controller.

I hope that is what you were asking about.

Also, if you are going to use cached maps  (and you will) you need to enable cache maps in background in the GO App.  So the cached map will stay.

thanks for the feedback, the rth was the most important thing i was concerned about.  Is there any truth to turning off the wifi signal while in the air to airplane mode?  i see people saying interference with devices if wifi is turned on after lift off.