From Halopedia, the Halo wiki
The Aviator helmet has a pilot-centric HUD integration. This ultrawideband machine interlink gives Spartan-IV pilots unparalleled control over their aircraft. The helmet also has a pressure-stabilized rebreather feed.
For decades the notion of specialized pilot armor for Spartans was thought redundant given MJOLNIR variants were already suited for the rigors. With the segregation of the Spartan-IVs into their own autonomous branch, the need for multiple intra-organizational disciplines materialized. This led to the Aviator variant's creation.
Aviator was manufactured by Hannibal Weapon Systems and tested at WG/Facility 93-00/Kotka. It was build from the ground up and was designed for the operation of GA-TL1 Longswords, YSS-1000 Sabres, F-41 Broadswords, and B-65 Shortsword bombers.
Spartan pilots meeting D3-17 regulations and higher are required to use this armor in Broadsword A/X attack fighter engagements operations to comply with standard asset security protocols and the Budgetary Retention Hearings of 2554.
Because of the increased production of the vehicles the Aviator armor was made for, this variant has become popular among Spartans. It is employed by the Spartan interceptor pilots attached to the security of ANVIL Station.
Halo 3 MCC
In the Halo: The Master Chief Collection version of Halo 3, the Aviator variant was added as part of Season 5: Anvil content. With the updated Halo 3 armor customization options, the players can now fit their Spartan with Aviator helmet, chest, shoulders and legs; the set is one of six to not recieve any associated forearm options. The description of the armor pieces are the same for every set.
Halo 5: Guardians
Available skins: Ace, Csar, and Delta
In Halo 5: Guardians due to the "Body" having a predefined customisation this armor set permanently has the following parts from Halo 4:
Halo 4 skin
Halo 5: Guardians skins
Halo 5: Guardians REQ cards
List of appearances