Which control system primarily maintains directional stability in flight?

• A. Yaw damper
• B. Aileron trim
• C. Elevator
• D. Rudder effectiveness

Answer: (A)

Directional stability is about resisting motion about the vertical axis and keeping the aircraft pointed along its flight path. A yaw damper acts as an automatic feedback system that senses yaw rate and applies a corrective rudder input to oppose that yawing motion. By continually damping yaw, it stabilizes the airplane against oscillations like Dutch roll and helps maintain a steady heading, especially in gusty conditions or at high speeds where yaw tendencies are stronger. The other items describe what happens when you move the surfaces or how effective the rudder is, but they don’t provide the automatic stability-damping function that the yaw damper delivers.