How do you deal with something grabbing onto a flying creature? Does its speed become 0 and start to plummet?

— Franco Balerio (@FrancoBalerio) August 8, 2017

The grappled condition reduces any speed you have to 0. If you have a flying speed, it's now 0, and you fall unless you're hovering. #DnD https://t.co/KUjxluCLbL

— Jeremy Crawford (@JeremyECrawford) August 8, 2017

So if you are flying under the effects of the Fly spell and you become grappled you fall? (Presumably taking the grappler with you)

— SebastianDELCASTILLO (@sdelcastillo) August 8, 2017

The flying rules specifically say that being held aloft by magic prevents you from falling if your speed is 0 or you're prone (PH, 191) #DnD https://t.co/hM4AEeGPvZ

— Jeremy Crawford (@JeremyECrawford) August 8, 2017

Thanks for the clarification. I looked at the Fly spell, not the move rules. So this applies to Aarakocras or other winged flyers. No problem!

— Jeremy Crawford (@JeremyECrawford) August 8, 2017