Which axis runs down the center of the aircraft?

The longitudinal axis is the axis that runs down the center of the aircraft, extending from the nose to the tail. This axis is crucial in understanding the orientation and movement of the aircraft in flight. It plays a key role in roll movements, which involve the rotation of the aircraft around this axis. Control surfaces such as ailerons operate along the longitudinal axis, enabling pilots to maneuver the aircraft effectively.

In contrast, the lateral axis extends from wingtip to wingtip, while the vertical axis, which runs from the top to the bottom of the aircraft, impacts yaw movements. The horizontal axis does not specifically apply in the context of an aircraft's movement and structure in aviation terminology. Understanding the significance of the longitudinal axis equips you with the foundational concepts needed for further studies in aviation dynamics.