An imaginary line running vertically through the center of gravity of an aircraft.
The labeled straight line at the side of a graph that runs up and down, or vertically. It is also called the Y-axis.
The axis extending straight up and down through the center of gravity of an aircraft. The vertical axis is perpendicular to the longitudinal and lateral axes. The vertical axis is sometimes called the "z" axis. Yaw is a motion around the vertical axis.