Floor drains are good.
For example, St. Louis County recently opened a new jail. After one flood from upper-story firefighting, the US Senate Computer Center did something along these lines I haven't seen elsewhere but wasn't a bad idea. The leading edges of the rolls were folded over a strip of wood, and a rope tied to that. Far faster than unfolding tarps. No statistics available, but I would suspect water flowing down is far more common than airplanes flowing down.