Plain English Meaning

When you correct too hard or too fast, the airplane swings past your target, you correct back, and it swings past the other way. The needle keeps rocking back and forth instead of settling.

Full Definition

A back-and-forth swinging of an instrument indication that occurs when a pilot makes corrections that are too large or too rapid, causing the aircraft (and the instrument needle) to overshoot the intended value in one direction, then overshoot again the other way. The effect is most commonly discussed in partial panel flight, where the loss of primary attitude information makes smooth, small inputs essential to prevent the heading, altitude, or airspeed from cycling above and below the target value.