The force of moving air steers an airplane. Steering is done through a system of moveable flaps, working much like boat rudders – that are located on the plane’s wings and tail. When set at an angle, they push at flowing air that pushes back, turning or tilting an airplane. To descend, for instance, a pilot lower a plane’s tail flaps, causing airflow to direct its nose downward. Turning requires changing the direction of wing flaps and the tail rudder.