Which primary flight control surface controls roll about the aircraft's longitudinal axis?

• A. Ailerons
• B. Elevators
• C. Rudder
• D. Flaps

Answer: (A)

Roll is the motion around the nose-to-tail axis of the airplane. The primary surface that creates that roll is the aileron. When you move the control, the two ailerons deflect in opposite directions—one wing’s aileron goes up while the other goes down—producing less lift on one wing and more lift on the other. This differential lift tips the wings and rotates the aircraft about the longitudinal axis. Elevators control pitch, moving the nose up or down about the lateral axis; the rudder controls yaw, turning the nose left or right about the vertical axis. Flaps change lift and drag for takeoff and landing and aren’t used to roll the aircraft.