Helicarrier

"Gentlemen, you might want to step inside in a minute. It's going to get a little hard to breathe." "Is this a submarine?" "Really? They want me submerged in a pressurized metal container?"

- Natasha Romanoff, Steve Rogers, and Bruce Banner

The S.H.I.E.L.D. Helicarrier is a high-tech flying aircraft carrier, specifically designed to be capable of independent powered flight in addition to the conventional functions of aircraft carriers.

The First Helicarrier
The first Helicarrier was constructed before 2012, and it was put in use by S.H.I.E.L.D.. After the "Big Week", the Helicarrier was docked at a secret US Naval Base. A spy infiltrated the ship and tried to steal Nick Fury's data about the Avengers Initiative, but he was intercepted by the S.H.I.E.L.D. agent Natasha Romanoff and it was revealed to be a security exercise.

In May 2012, Fury brought Tony Stark, Bruce Banner, and Steve Rogers on board the Helicarrier, trying to form a team that could protect the Earth better than S.H.I.E.L.D. ever could. However, because of Loki's manipulations, all members of the team showed not even the slightest trace of unity and teamwork.

When the Helicarrier fell under attack from Loki's mind-controlled soldiers, it was heavily damaged; yet it was still able to limp to open water on the strength of only three of its colossal fans. When the Chitauri invaded New York City, the World Security Council ordered Fury to fire a nuclear missile at the city, but he refused. When one fighter plane tried to fly from the carrier, Fury stopped it with a rocket launcher. However, he was unable to stop the second plane which fired the missile. Thanks to Iron Man, the missile was redirected, destroying the Chitauri flagship, which effectively ended the invasion.

Project Insight
"This is Project Insight. Three next generation Helicarriers synced to a network of targeting satellites." "Launched from the Lemurian Star." "Once we get them in the air they never need to come down."

- Nick Fury to Captain America

After the battle of New York, the World Security Council granted S.H.I.E.L.D. more funds to invest in homeland security, for which "Project Insight" was created, a security network formed by three heavily-armed Helicarriers to protect the Earth. After having a "close look" at the propulsion systems of the Helicarrier during the War for Earth, Tony Stark had them upgraded with his more efficient repulsor technology; present in every Project Insight Helicarrier. These helicarriers were destroyed by the Falcon, Maria Hill, and Captain America.

Capabilities
The Helicarrier is a seaworthy ship capable of VTOL flight by way of four huge lift fans mounted on the sides. It has two runways, one with direct access to a hangar at the rear is aligned along the spine of the vessel and is used for forward launches of aircraft, and the other diagonally aligned runway above is suitable for landings.

The Helicarriers created under Project Insight were next-gen and more advanced than the original. They were more heavily armed with long range dorsal and ventral guns and cannons and have repulsor-powered engines instead of the old turbine-powered engines. Fury commented that this was done due to input from Stark who "was up close and personal" with the old engines.

S.H.I.E.L.D. Helicarriers have retro-reflective panels lining their hulls, making them invisible to normal human vision below a certain elevation. They also possess radar cloaking capabilities, making them difficult to detect by other means. Helicarriers are the only known S.H.I.E.L.D. vehicles to receive such extensive cloaking capabilities, unlike the smaller vehicles, such as The Bus.

Known Helicarriers

 * Helicarrier No. 64
 * Helicarrier IN-01
 * Helicarrier IN-02
 * Helicarrier IN-03

Trivia

 * In the comics, the Helicarrier was more of a glass dome. Joss Whedon felt it would be more realistic if it was more like an aircraft carrier.