Plain English Meaning

It's the habit of looking at several flight instruments in turn — not just one — to check whether the nose of the airplane is set at the right angle and is doing what you want it to do.

Full Definition

The systematic scanning of the pitch instruments — attitude indicator, altimeter, vertical speed indicator, and airspeed indicator — to determine and verify the airplane's pitch attitude during instrument flight. The attitude indicator is the primary reference for setting pitch, while the altimeter, VSI, and airspeed indicator are used to confirm that the selected pitch attitude is producing the desired performance.