What is a trim tab?

A trim tab is an auxiliary control that is mounted on a primary control surface, such as an aileron, elevator, or rudder. Its main function is to balance the aerodynamic forces acting on the control surface, allowing the pilot to maintain a stable flight attitude without constant control input. By adjusting the trim tab, the pilot can change the airflow over the control surface, thereby reducing the amount of force needed to hold it in a specific position. This assists in alleviating pilot workload during flight, particularly on long flights or when flying at constant airspeeds and altitudes.

The other options do not accurately describe a trim tab. For instance, while a fixed wing component refers to parts of the aircraft that do not move, trim tabs are indeed movable components. The idea of an adjustable part of the cockpit does not pertain to trim tabs, as trim tabs are located on control surfaces and not within the cockpit. Lastly, a control for landing gear describes a completely different function related to the aircraft's landing system and has no connection to the aerodynamic balancing role of trim tabs.