What is the function of a trim tab on an aircraft?

The function of a trim tab on an aircraft is primarily to adjust the aerodynamic balance of control surfaces. Trim tabs are small adjustable surfaces attached to the primary control surfaces, such as the elevator, ailerons, or rudder. They allow pilots to fine-tune the position of these primary control surfaces, making it possible to maintain straight and level flight without constantly having to exert pressure on the control yoke or stick.

By positioning the trim tab, the pilot can create a small aerodynamic force that counteracts unwanted moments or tendencies in the aircraft’s flight behavior, such as nose up or down attitude, which can enhance comfort and reduce pilot fatigue. This adjustment is crucial for smooth flying since it helps maintain the desired flight attitude with minimal effort.

The other options do not accurately describe the primary function of trim tabs. For instance, increasing the pilot's workload is counterproductive to what trim tabs are designed to accomplish. Similarly, reducing fuel consumption and controlling cabin humidity are unrelated functions in the context of an aircraft's control surfaces.