fly by the seat of your pants
fly by the seat of (one's) pants
To rely on one's instinct, as opposed to acting according to a set plan. I really don't know how to operate this thing, I'm just flying by the seat of my pants here. You can't just fly by the seat of your pants, Jenna—please give your future some serious thought.
fly by the seat of your pantsINFORMAL
If you fly by the seat of your pants, you use your judgment and intelligence to do something that you have never done before, in a way that is risky, because you have no experience or training to rely on. `In the first year of trading we knew nothing and were flying by the seat of our pants,' Petti said. The truth is that all new parents fly by the seat of their pants and try to learn quickly from experience. Note: You can also use seat-of-the-pants before a noun. It had always been a seat-of-the-pants type of organization.