What does a balance tab do?

A balance tab serves a specific purpose in the realm of aircraft control surfaces. Its primary function is to assist the pilot in moving the control surface more easily, which is achieved by providing a force that aids in the movement of that control surface. When the pilot applies force to the control yoke or stick, the balance tab moves in the opposite direction, generating aerodynamic forces that help to offset some of the control surface's resistance to movement. This reduction in required force helps in enhancing the control responsiveness and feel for the pilot, particularly during aircraft operation at various speeds and conditions.

For context, the other options do not accurately describe the function of a balance tab. While a balance tab does play a role in elevator control, it is not limited to just that application, making the reference to elevator control too narrow. Additionally, a balance tab does not move in the same direction as the flight control's trailing edge; rather, it moves in the opposite direction to create the effective force. Finally, it is distinct from an anti-servo tab, which has a different function related to stability, particularly in maintaining control surface position rather than assisting movement.