Which system counteracts Dutch roll in many swept-wing aircraft?

In many swept-wing aircraft, the system that counteracts Dutch roll is the yaw damper system. Dutch roll is a specific type of oscillatory motion involving yaw (side-to-side movement) and roll (tilting movement) that can occur in aircraft with high wing sweep angles. The yaw damper system is designed to provide automatic corrections to the yaw motion, stabilizing the aircraft and preventing these oscillations from growing in amplitude.

The yaw damper works by sensing the aircraft's movement and making small adjustments to the rudder's position, which helps to dampen the yaw oscillations that characterize Dutch roll. By effectively stabilizing the aircraft in the yaw axis, the yaw damper enhances overall flight safety and passenger comfort, particularly during cruise flight when this oscillation tendency can be more pronounced.

Other systems listed, such as pitch control, stabilators, and roll control systems, play crucial roles in an aircraft's overall stability and control but do not specifically address the unique challenges posed by Dutch roll. Thus, the yaw damper system is essential in managing this particular behavior in swept-wing designs.