What device is commonly used to counteract Dutch roll in modern aircraft?

Yaw dampers are specifically designed to counteract Dutch roll, which is a type of oscillation that can occur in aircraft flight characterized by a combination of roll and yaw motions. This phenomenon typically arises in swept-wing aircraft, where aerodynamic characteristics can lead to instability.

Yaw dampers work by automatically adjusting the rudder movement to stabilize the aircraft during these oscillations. When the aircraft begins to experience a Dutch roll, the yaw damper detects the motion and provides corrective inputs to the rudder, helping to dampen the yaw oscillations and prevent the rolling motion from becoming excessive.

While ailerons, elevators, and rudder trim tabs serve important functions in controlling an aircraft, they do not specifically address the Dutch roll problem in the same way yaw dampers do. Ailerons and elevators are used for roll and pitch control respectively, while rudder trim tabs are mechanical devices that adjust the position of the rudder but do not actively respond to real-time flight dynamics like yaw dampers do. Hence, the correct answer focuses on a device that actively mitigates a specific stability issue.