What is "secondary flight control"?

Secondary flight controls are systems designed to enhance the performance and effectiveness of the primary flight controls, which typically include ailerons, elevators, and rudders. These secondary systems can include flaps, slats, speed brakes, and trim systems, among others. Their main function is to improve the aircraft's aerodynamic characteristics, increase lift during takeoff and landing, provide better control at various speeds, and enhance stability, all of which contribute to better overall flight performance.

The key aspect of secondary flight controls is their supportive role to the primary controls, allowing pilots to manage the aircraft more effectively under different flight conditions. For example, extending flaps increases lift at lower speeds, which is crucial during takeoff and landing phases. This interaction between primary and secondary controls is vital for optimizing aircraft handling and safety.

In contrast, the other options address aspects that do not align with the definition of secondary flight controls. Controls that operate independently of primary controls do not typically enhance performance directly; rather, they may serve different functions altogether. Similarly, controls that disengage autopilot systems do not enhance control performance, and those that solely function in manual flight disregards the multifunctional capabilities of secondary flight controls that work in conjunction with both manual and autopilot operations.