Flies by the seat of his pants. Completely unpredictable.
5 seconds sound clip from the Top Gun (1986) movie soundboard.
You can hear this line at 00:36:56 in the Blu-ray version of the movie.
Quote context
[...]
- I really enjoyed that, Mav, thanks a lot.
- Maybe I could learn how to be a truck driver.
- His fitness report says it all. He's a wild card.
- Flies by the seat of his pants. Completely unpredictable.
- Yeah.
- Maverick. I flew with his old man.
- Tell me one thing. If you had to go into battle, would you want him with you?
- I don't know. I just don't know.
- Yeah.
[...]