Which axis passes vertically through the center of gravity?

• A. Vertical axis
• B. Longitudinal axis
• C. Lateral axis
• D. None

Answer: (A)

The vertical axis. In aircraft geometry, the three principal axes intersect at the center of gravity: the vertical axis runs perpendicular to the plane of symmetry, going up and down through the aircraft, and is the yaw axis. Turning about this axis—caused by rudder inputs—makes the nose yaw left or right while the wings stay aligned relative to that axis. The other two axes run along the fuselage (nose to tail) and wing-to-wing (left to right) and correspond to roll and pitch motions, not vertical rotation. So the axis that passes vertically through the center of gravity is the vertical axis.