Which control surfaces are primarily used to control the longitudinal axis?

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

Answer: (A)

Controlling the longitudinal axis means rolling the aircraft about the nose-to-tail line. Ailerons are the primary surfaces used for this. Located on the trailing edges of the wings, they move in opposite directions—one up, the other down—which creates differential lift. The wing with the lowered aileron increases lift and rises, while the opposite wing loses lift and lowers, tipping the aircraft into a bank and producing a roll about the longitudinal axis. Elevators affect the pitch about the lateral axis (nose up or down), rudder controls yaw about the vertical axis (nose left or right), and flaps mainly change lift and drag during takeoff and landing rather than roll.