Bus

"Officially, it's an Airborne Mobile Command Station, but we call it the Bus."

- Leo Fitz to Skye

The Bus (formally known as the CXD 23 Airborne Mobile Command Station officially designated as "S.H.I.E.L.D. 6-1-6".) is a specialized Boeing C-17 Globemaster III owned and modified by S.H.I.E.L.D. It served as a flying command center for Agent Phil Coulson and his team before being stolen by Grant Ward. It was originally piloted by Melinda May.

Capabilities and Design
The Bus is a specialized Boeing C-17 Globemaster III modified to serve as an  'Airborne Mobile Command Station' for Agent Coulson's personal S.H.I.E.L.D. team. In addition to the common features of the Boeing C-17, the Bus has an additional pair of engines and half-length wings located at the tail section of the fuselage, below the conventional, elevated tail section. This gives the Bus greater aerodynamic and flight capabilities, making it better able to transport the team for great distances to points of interest in a prompt amount of time. Additionally, the six engines are able to pivot up on each wing, allowing them to be angled at the ground, giving the Bus Vertical Take-Off and Landing (VTOL) capabilities. On top are mounts and an access way to allow a Transport Plane to dock midair, which may also separate midair. In addition, the Bus does have offensive/defensive capabilities in the form of built-in cannons able to shoot down any enemy aircraft. The Bus is also capable to be controlled by anyone at the Hub or any major S.H.I.E.L.D location. It can be used to fly to a certain location, speed and altitude. Its cargo doors, among other things, have the capability to be opened by any SHIELD car, such as the field car that many agents use in the field. It also can change course, altitude and speed at any location in the aircraft. The Bus also has encrypted lines to speak to any agent on the ground at SHIELD locations as well as their alllies. It has capabilties to also receive any mission briefings and missions from the Triskelion and the Hub.

While the majority of a conventional C-17's interior is open cargo space, the Bus has been modified to suit the needs of Coulson's S.H.I.E.L.D. team including three passenger decks replacing the forward cargo space. The passenger space includes an interrogation room (whose walls are built with silicon-carbide Vibranium alloy), living quarters, a briefing room, a number of various storage rooms, and a private forensics and research lab to accommodate Agents Leo Fitz and Jemma Simmons. The highest deck of the Bus, near the front of the plane also houses agent Coulson's personal office. The Bus retains a small cargo area at the rear of the plane where the team's SUV is stored along with Coulson's personal car, Lola. The Bus also contains a removable medical pod that was used by Skye. The Bus also has all specs and information on the many operations that Coulson's Team has been involved with, including the various items and individuals that the team has come in contact with, in a separate data line individual from that of the main S.H.I.E.L.D. database.

The Bus does not have the stealth technology that the Helicarrier has, so it compensates by flying under radar.