@ReubenFontanaWhat happens to a character with the fly spell if he is incapacitated? Assume the flier is not the caster. Falls? Hovers? The character hovers. Check out “Flying Movement” in the Player’s Handbook (page 191).

— Jeremy Crawford (@JeremyECrawford) January 31, 2015

@ReubenFontanaSorry, does this hold for unconscious/stunned/paralyzed/petrified? I thought so, but running into disputes. “does this hold for unconscious/stunned/paralyzed/petrified?” Yep

— Jeremy Crawford (@JeremyECrawford) February 2, 2015

Sage Advice: Master Sage Jeremy refers to “Flying Movement” at p.191 that specify that Fly spell (or similar) can hover creature if are incapacitated. Fly spell is in the PHB p.243