Adverse Yaw

What is Adverse Yaw?

When a pilot uses ailerons to roll the aircraft, the upgoing aileron reduces lift (and induced drag) on one wing, while the downgoing aileron increases lift (and induced drag) on the other. This imbalance in drag causes the aircraft to yaw in the direction opposite to the intended turn—a phenomenon known as adverse yaw.

Why Does Adverse Yaw Occur?

• The wing with the downward-deflected aileron produces more lift and more induced drag.
• The wing with the upward-deflected aileron produces less lift and less induced drag.
• This drag difference creates a yawing moment opposing the roll direction.

Methods to Reduce Adverse Yaw

• Differential Ailerons: The upgoing aileron moves more than the downgoing one, balancing drag between wings and reducing adverse yaw.
• Frise Ailerons: The leading edge of the upgoing aileron projects below the wing, increasing form drag on the upgoing wing to counteract the drag difference.
• Rudder-Aileron Cross-Coupling: Automatic or manual rudder input is coordinated with aileron input to offset yaw.
• Roll Spoilers: On larger or faster aircraft, spoilers can be used to assist roll and reduce the need for large aileron deflections, minimizing adverse yaw.

Operational Relevance

Pilots must recognize and correct for adverse yaw, especially during turns, by using coordinated rudder input or relying on design features that minimize its effect. Uncorrected, adverse yaw can lead to uncoordinated flight and inefficient or unsafe maneuvers.