First, thanks to all who have shared their experiences both good and bad.

I've read that one should cache maps on the phone or tablet used to fly the Phantom when outside of cell range for the device.  I use an ipad mini with wifi only, no cell capability.

To cache maps...
First, what is the map application used by the system so I know which to cache?
Second, what is the reason for caching maps?  Where will it be of value to the pilot?

Thanks in advance for factual answers and not for guessing.

The GO app and Litchi (Autopilot/VerticalAI too)  use Google maps via internet connection.

The advantage is seeing where your drone is on a google map during flight so you can orient yourself and the drone to surrounding structures, etc.  If you don't care about that, then you don't need to pre-cache the maps.  Just go fly.

You don't load a separate app to cache the maps.  Simply load whatever app you fly with (Go, Litchi, Autopilot, VerticalAI, etc).  Then, while connected to the internet, scroll the map to the area you will fly.  Zoom in and out to get all levels.  This downloads, or caches, the map images on your tablet/phone's drive(sd card).  Then, later, when you are no longer connected to the internet, the app will recall the images from the drive cache during the flight.  Its as simple as that.

Right on.  Thanks.  That will be helpful as I plan to fly my P3P in the woods soon.  No cell coverage and certainly no wifi.

In the Go app you will find a button 'Cache Maps', that needs to switched to On, in order for this action to actually work.
When you open the app, in the bottom right corner it shows a map, with your home point, just open that, switch from camera view to the map and scroll, or move it to your chosen flight area,.
Now expand it, as big as it will go, and move it around slowly. Viewing it, well beyond your designated flight area.
Sometimes it doesn't work. I have arrived at my flying destination, only to find a grey map area. Frustrating.

RedHotPoker