on the fly

Idioms  

1. In a hurry, on the run, as in I picked up some groceries on the fly. The transfer of this expression, which literally means “in midair or in flight,” dates from the mid-1800s.

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Example Sentences

That includes “extended range electric vehicles,” battery-powered cars that have an onboard generator, running on gas, that recharges batteries on the fly.

From Barron's

The Rams may also have to adjust on the fly.

From The Wall Street Journal

“With handing off, you can’t be fooling around and changing it on the fly. You have to practice it during the week.”

From Los Angeles Times

“We were learning on the fly, getting extra security, managing ticket sales, creating guest lists. It was a storybook situation.”

From Los Angeles Times

Changes were ordered on the fly in response to feedback.

From The Wall Street Journal