[5E] If no hover & not moving & trapdoor opens do they fall?

[excommunicated]

Does a flying creature or character with winged boots or other means with no hover is standing still when the floor is removed (trap-door or similar), do they fall. Is there a RAW on this?

[Kane0]

There is not. Presumably gravity affects them normally, though most DMs would probably allow some sort of Dex save to grab a ledge or take flight