Adverse Yaw

When an airplane is rolled into a turn, the aileron on the rising wing is lowered and the wing produces more lift, which also produces more drag. That added drag slows the rising wing slightly, so the airplane yaws toward the wing that experienced the increase in lift and drag. From the pilot's seat, the yaw is opposite the direction of the bank. The Pilot's Handbook of Aeronautical Knowledge describes adverse yaw as a result of differential drag and the slight difference in velocity of the left and right wings.

Adverse yaw becomes more pronounced at low airspeeds, where aerodynamic pressure on the control surfaces is low and larger control inputs are needed. It is reduced, but not eliminated completely, by features such as differential aileron travel and frise-type ailerons.

The pilot corrects it with rudder, applied in the direction of the turn and coordinated with the aileron input. Uncoordinated flight at low speed and high angle of attack is a recognized precursor to a spin, which is why coordination is examined at every certificate level.