I'm thinking about getting a dedicated mobile phone for the Mavic controller.  Are there any critical flight functions that require cellular data and thus a SIM?

Thanks,

Pat

You can get a non-cellular phone and cache your google maps with WIFI before you go to your flying location.
You can always tether to a mobile phone if you DO need data. This way you can do firmware updates in the field. They seem to be updating every few days !!!

I'm using my Ipad Mini 3, Wifi only. I just make sure to cache maps beforehand and check for any app/firmware updates before heading out to fly.

This is what I want to do. I worry about damaging or losing my iPhone so thinking of getting a low cost android phone to do the job. I'm so old school tho when it comes to this sorta stuff. I know iPhones need a SIM to set them up. Do androids?