DCHP-1 Online
seat of one's pants 
in fly by the seat of one's pants, in the manner of a seat-of-the-pants flyer.
- 1966 What [they] are trying to find out is why and how a good bush pilot can fly "by the seat of his pants."
- 1966 And they flew (as, indeed, they had to fly, for there were few aids to navigation) "by the seat of their pants."
- 1966 What [they] are trying to find out is why and how a good bush pilot can fly "by the seat of his pants."