Hangar A-01
From Halopedia, the Halo wiki
Hangar A-01, also known as Hanger Bay A, is a generic United Nations Space Command term for one of the two-story Pelican hangers on the port side of an Orbital Defense Platform.
Cairo Station Hanger A-01
During the opening actions of the Battle of Earth, Covenant boarders invaded Hangar A-01 directly. A Covenant Boarding Craft had docked and sent forth waves of Unggoy and Sangheili. Marine defenders, equipped with Battle Rifles, SMGs, and even a Machine Gun Turret, were being overwhelmed at their position at the second floor when John-117 came to assist, killing all the Covenant and repulsing them back to their landing ship. John-117 then moved to adjacent Hangar A-02. The Marines suffered only minor casualties. It is here where they witnessed the destruction of the Malta.