Fly By The Seat Of One's Pants Meaning

(idiomatic, by extension) To use one's judgment, initiative, and perceptions as events unfold in order to improvise a course of action without a predetermined plan.

Example: 1955 Feb. 21, "Planes for Pleasure," Time:
  Between world wars, when Douglas Bader was a cocky, teen-age R.A.F. cadet . . . a man could navigate by eye and the nearest railroad track and fly by the seat of his pants.
2010 Jan. 14, Jacob Heilbrunn, "Election Confidential," New York Times (retrieved 25 June 2011):
  â€œUnlike Obama and his methodical process, McCain was flying by the seat of his pants,” the authors observe.