Abstract: A door assembly is provided for an aircraft that has a fuselage with a protective skin and an access opening therein. The door assembly includes a pair of parallel tracks mounted on opposite sides of an access opening in the fuselage. A sliding door is secured to the tracks and is mounted thereon for reciprocal movement therealong. Some releasable restraining mechanism is provided for immobilizing the door relative to the tracks. A sliding aircraft door according to the invention allows openings of greater size to be employed in aircraft. Also, the system is far less complex, more economical to build, and lighter in weight then conventional aircraft door assemblies. The reduced weight results in greater fuel economy during flight, while the simplicity of construction reduces the likelihood of a malfunction in the door mechanism.