From Halopedia, the Halo wiki
Firing control is a generic United Nations Space Command term for any center or position referring to the operations of weapons systems aboard a warship, such as a UNSC frigate or Orbital Defense Platform.
UNSC starship firing control
The Firing Control Officer, or simply Weapons Officer, aboard a frigate or destroyer is rank of Lieutenant, like Lieutenant Hikowa of the UNSC Iroquois. They are in charge of Archer missile and Magnetic Accelerator Cannon firing solutions.
Cairo Station firing control
Cairo Station firing control was the Magnetic Accelerator Cannon firing control station of Cairo Station. During the Battle for Earth, Covenant boarders invaded firing control, killing all the crew and Marines (except one who was hiding behind a set of stairs) stationed there and planted a large bomb planned to destroy the orbital station, similar to how the nearby Athens and Malta stations were destroyed. John-117 and Cortana managed to disarm the bomb just in time (with seven seconds left) and later redeployed it to destroy a Covenant assault carrier.
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