Armory A-01
From Halopedia, the Halo wiki
Armory A-01 is a generic United Nations Space Command term for any armory and armor testing facility on the port side of an Orbital Magnetic Accelerator Cannon Platform.
Cairo Station Armory A-01
Cairo Station Armory A-01 was the United Nations Space Command armory on the port side of Cairo Station. During the First Battle of Earth, Covenant boarders invaded Armory A-01. Stealth Elites armed with Plasma Rifles killed the Master Sergeant, who was equipped with a shotgun. SPARTAN-117, from Hangar A-02, moved too slowly to save the UNSC soldier, but was able to avenge him.