Alternatives to flying by the seat of your pants

Question

What is the actual meaning of the idiom flying by the seat of your pants.

I have searched online but could not properly understand the meaning. Would it be possible to use the idiom in the following situation:

A plaintiff commences a baseless legal action against a defendant, where he provided no material facts supporting his claim. To defend himself, the defendant has to follow his instinct instead.

Example:

Defending the action would be like flying by the seat of his pants

If the usage sounds akward, are there any phrases or idioms to best describe it.

Answer 1

The sentence you give makes sense to me. I think I’d be more likely to say, “Defending this case, I’ll be flying by the seat of my pants. I don’t even know what evidence they think they have or what their argument is going to be at trial, so I’ll have to be ready for anything.”

Some alternatives would be, improvising, making it up as I go along, extemporizing, taking it as it comes, playing it by ear, freestyling and winging it. More prosaically, reacting.

Answer 2

"Flying by the seat of one's pants" means improvisation, reacting based on moment to moment perceptions or instinct without an overall plan.

The original meaning was to fly an airplane (usually a small plane) without instruments, depending on the kinesthetic sense of the motion of the plane conveyed to the pilot by contact with the plane though hands and feet, but particularly through the pilot's seat.