Thanks, you guys. It is a new Mavic Pro and it came with a 16 GB card already inserted into the AC's card slot. During my first few maiden flights I took both stills and video with that card and it recorded just fine. That's why I was unsure if formatting is an auto-process in the AC at start-up or if that card had been formatted by some other method prior to leaving the factory. Out of curiosity, what exactly does formatting do, which would answer why is it necessary? My Canon DSLR cards need to be formatted too. It's great to have this forum as a resource, I really appreciate the community that supports all of this sharing of information.