Phoenix-class colony ship

The Phoenix-class is a colony ship classification used by the Unified Earth Government, with a hull classification symbol of CFV. In addition to ferrying colonists to newly settled worlds, they are used to carry equipment such as prefabricated colony starter units, hydroponics and other facilities. Known ships of the Phoenix class include the which colonized Harvest and the  which aided in the colonization of Arcadia and was later converted into a warship.

Specifications
The Phoenix-class is 2.5 km long, making it one of the largest known UNSC ships in the organization's naval history.

The Phoenix-class ships were designed to transport thousands of colonists from Earth, or one of the other Inner Colonies, as well as terraforming equipment to alter the existing atmosphere and/or biosphere to become compatible with human habitation. Once the terraforming is completed, the colonists settle the planet. On at least one instance, a colony ship was decommissioned to aid in the development of a colony. On Harvest, the Skidbladnir's fusion reactor was used to power the first settlement, Utgard and its data processing storage housing the Agricultural Operations AI, Mack was also utilized. The ship's AI, Loki, became the Planetary Security Intelligence, sharing a core with Mack, covertly monitoring the colony for trouble for the UNSC. Whether this was a common fate for colony ships during the colonization of other worlds is unknown.

Modifications
At least one Phoenix, Spirit of Fire, was modified for wartime use by the United Nations Space Command and redesignated a Phoenix-class support vessel. The refitted ships carry vehicles, troops, and supplies as support for ground forces. It also carries the resources necessary to build firebases, with the base structures being repurposed colony starter units.

Once converted, a Phoenix-class ship can become an extremely effective troop transport and orbital support ship, carrying thousands of Marines, significant supplies and equipment, and, if equipped with a Magnetic Accelerator Cannon during conversion, is able to attack ground targets from orbit in support of ground operations. It can also use Pelican, Albatross dropships and Pods to deploy ground forces and establish bases of operation. It is even able to participate in atmosphere to a degree. However, despite the conversion of the Phoenix-class from a colony transport ship to a warship, it is still underpowered as far as most warships go; the super-structure of the Spirit of Fire is vulnerable to light pulse laser fire, and despite the addition of armor plating, the outer edges of the hull were ripped away when the ship nearly collided with a Covenant destroyer. The Magnetic Accelerator Cannon can fire multiple times consecutively, but each round is less powerful than the cannons used by other UNSC warships.

Ships of the line

 * - Lead ship of the Phoenix-class.
 * - Missing, presumed lost in 2531.
 * - Scrapped for materials.

Trivia

 * The phoenix was a mythological bird which would be reborn at the end of its lifetime; in a similar fashion, the Phoenix-class colony ship would be decommissioned and stripped down upon colonizing a planet, the ship's materials "giving birth" to a new colony.
 * The name Phoenix may be a reference to Bungie's canceled game of the same name, or, more likely, the name is derived from an Ensemble prototype which pitched humans against invading Martians in a War of the Worlds style, which was titled Phoenix.
 * The Halo Encyclopedia claims the Spirit of Fire to be three miles long.

List of appearances

 * Halo: Contact Harvest
 * Halo Wars: Genesis
 * Halo Wars
 * Halo Legends
 * Origins
 * Halo: Fall of Reach
 * Boot Camp
 * Halo: Escalation
 * Halo: Fleet Battles