Longitudinal axis
An imaginary line, passing through the center of gravity of an airplane, and extending lengthwise through it from nose to tail.
Aviation Maintenance Technician Handbook — Airframe, p. G-21
Also defined in 2 more sources
An imaginary line through an aircraft from nose to tail, passing through its center of gravity.
An imaginary line through an aircraft from nose to tail, passing through its center of gravity. The longitudinal axis is also called the roll axis of the aircraft. Movement of the ailerons rotates an airplane about its longitudinal axis.