Mavic controller can go in checked bags as it has the battery contained within it.
Ideally protect the 'on' button but that is easy with one of the cheap 'hard' pouches on ebay.
Oh I didn't know if it has the battery contained with it then you can travel it in your checked bag. Turkish airlines never mentioned that to me. Sounds like theyr not entirely sure. I think I might just risk traveling with the spark with the battery connected on the way back. I think traveling with it in hand bags have more chance you'd be refused to bring it.
But the airline did say they will wrap up restricted electronics in bubble wrap and put it in a seperate compartment in the hold. Which begs the question is it really safer than having it in your own hold bag ? What are they using fireproof cases or something...