fly by

fly blind

To do by guesswork; to feel one's way.

fly by the seat of one's pants

To pilot an aircraft without the aid of instruments and without a flight plan, using only instinct, visual observation, and practical judgment.

fly in the face of

To act in a manner highly contrary to; to counteract or contradict.

fly in the ointment

Something (especially a minor thing) which ruins or spoils everything else, or makes it less pleasant; a nuisance or problem; a disagreeable or unpleasant detail.

fly low

To have one's fly (zipper) undone.

fly off

To flee rapidly; to run away.

fly off at a tangent

To digress from a topic.

fly off the handle

To become very angry or enraged; to throw a fit or go crazy.