Which control surface is not a primary flight control?

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

Answer: (D)

Primary flight controls directly change the aircraft’s attitude: ailerons roll the airplane, elevators pitch the nose, and the rudder yaw the airplane. Flaps aren’t part of that set; they’re high-lift devices on the trailing edge that increase wing camber and lift at lower speeds. They’re used mainly to permit slower takeoff and landing and to steepen approaches by enhancing lift (with added drag), not to steer or rotate the aircraft in normal flight. So, although flaps affect flight characteristics, they don’t function as primary controls, which is why they’re the correct choice.