Idiom of the day: seat-of-the-pants

From A.Word.A.Day, it’s seat-of-the-pants: “1. Using experience, instinct, or guesswork as opposed to methodical planning. 2. Done without instruments.”

The origin is surprising to me:

The term has its origin in aviation. Before modern instruments, a pilot flew a plane based on how it felt. For example, in fog or clouds, in the absence of instrumentation one could tell whether the plane was climbing or diving by how heavy one feels in the seat. Seat of the pants is the area where one sits, i.e. the buttocks. Earliest documented use: 1929.

The Oxford English Dictionary has a first citation from Popular Science Monthly (October 1935) that points to a different meaning:

Ten years ago, blind flying was known as “seat-of-the-pants” flying, for fog-bound pilots without instruments soon learned to tell whether they were flying right-side-up by the pressure against their parachute packs.

Right now I’d say that were both upside-down and diving. It’s all seat-of-the-pants. And get this: the plane has instruments, but the pilot doesn’t trust them. He thinks his instincts are better.