What does roll or bank refer to in aircraft movement?

In the context of aircraft movement, roll or bank specifically refers to the rotational movement of an aircraft around its longitudinal axis, which extends from the nose to the tail. This motion is primarily controlled by the ailerons, which are hinged surfaces located on the wings. When a pilot wants to initiate a roll, they will deflect one aileron upward and the other downward. The upward-moving aileron reduces lift on that wing, causing it to drop, while the downward-moving aileron increases lift on the opposite wing, causing it to rise. This combination of actions results in the aircraft banking to one side, allowing for coordinated turns and control of attitude in flight.

The other options relate to different types of motion or control surfaces in aircraft. For instance, up and down motion controlled by the elevators pertains to pitch, while side-to-side motion controlled by the rudder refers to yaw. Forward thrust managed by the thrust reversers is related to deceleration during landing or slowing down, which does not pertain to the aircraft's bank or roll motion. Understanding these distinctions is essential for comprehending aircraft dynamics and control.