UNSC rank structure

The rank structure of the United Nations Space Command's mainline branches of service (the Navy, the Marine Corps, the Army, and the Air Force) is largely derived from the system employed by the 21st century United States military. Spartan Operations is an exception to this as its members lack conventional ranks.

Warrant officer
A warrant officer is a military officer in the Armed Forces ranking above a non-commissioned officer (NCO), but below a commissioned officer. Warrant officers are technical specialists and subject matter experts that are awarded an officer's commission in recognition of their expertise and leadership role. They take the officer's oath of service and are rated above enlisted soldiers, though remain subordinate to full officers. The rank structure of warrant officers consists of two ranks, as follows:


 * Warrant officer (WO): With the rank code of WO-1, a warrant officer serves as a resident technical expert, and may serve as a crew chief or pilot in the UNSC Army.
 * Chief warrant officer (CWO): With the rank code of WO-2, a chief warrant officer serves as a command advisor or or senior subject matter expert. In the UNSC Navy, they may be the captain of a utility ship.

Both the UNSC Navy and Army utilize warrant officers heavily, though they are rarely found in the Marine Corps. Both the Air Force and Spartan Operations are the only service branches that do not select or utilize warrant officers.

Trivia

 * The Halo Encyclopedia erroneously describes the structure and insignia of the UNSC's ranking system as being identical to those used in Halo multiplayer, Halo 3 in the original printing and Halo: Reach in the 2011 edition.
 * All Marine Corps ranks between Staff Sergeant and Sergeant Major are classified as Staff non-commissioned officers.