Posted by Dan on September 24, 2003
In Reply to: Fly by the seat of your pants posted by TheFallen on September 24, 2003
What I heard was that it referred to doing something risky on instinct alone. It was commonly used in the World Wars (especially the First, where instruments were rudimentary at best), as noted above, when a person's visibility was affected by fog, clouds, darkness, and so on. The pilot had to rely on instinct to navigate, judging the movement of the airplane by the vibration and shifts in gravity of the chair they were sitting in.