Sometimes called “the poor man’s autopilot,” secondary flight control surfaces commonly known as trim tabs literally take a load off pilots, allowing an airplane to be flown “hands off.”
However, like many things in aviation, there is a right way—and a wrong way—to adjust trim in flight.
First, a quick primer on trim systems.
Trim tabs are small, pilot-adjustable “flaps” on control surfaces, designed to catch the relative wind and aerodynamically balance the control in a given position. In other words, once trimmed, the control surface stays put without you having to manually hold it in that position. Your interface for adjusting the trim (most training airplanes only have elevator trim) is a vertical wheel typically located toward the base of the center panel in a training airplane’s cabin and/or an electric switch on the yoke, or, in older airplanes, a charmingly located hand crank on the ceiling.
Properly trimming an airplane allows it to virtually fly itself—at least in calm air. But even in turbulent skies, a properly trimmed airplane is less of a handful to fly and gives you the bandwidth to attend to other flight deck duties.
The right way to trim? First, pitch the airplane to the desired attitude using elbow grease (grandpa-speak for manual labor), then “trim off” excess control pressure. Hold the yoke with your left hand and work the trim control until you are neither pushing against it nor pulling it back. Let go of the yoke and make any final tweaks with small adjustments to the trim wheel.
The wrong way to trim is using the trim wheel like an auxiliary yoke to fly the airplane. Don’t. It’s sloppy, unprofessional, and not what the control was designed for.
In short, set the pitch attitude, then adjust the trim wheel to reduce control pressure.