Aircraft carrier
thumb|300px|Four modern aircraft carriers of various types—, Charles de Gaulle, , helicopter carrier —and escort vessels, 2002
thumb|upright=1.25|From bottom to top: Spanish light V/STOL carrier Príncipe de Asturias, amphibious assault ship , fleet carrier , and light V/STOL carrier , showing size differences of late 20th century carriers, 1991

An aircraft carrier is a warship that serves as a seagoing airbase, equipped with a full-length flight deck and facilities for carrying, arming, deploying, and recovering aircraft. Typically, it is the capital ship of a fleet, as it allows a naval force to project air power worldwide without depending on local bases for staging aircraft operations. Aircraft carriers are expensive to build and are critical assets. Carriers have evolved since their inception in the early twentieth century from wooden vessels used to deploy balloons to nuclear-powered warships that carry numerous fighter planes, strike aircraft, helicopters, and other types of aircraft. 

There is no single definition of an "aircraft carrier," and modern navies use several variants of the type. These variants are sometimes categorized as sub-types of aircraft carriers, and sometimes as distinct types of naval aviation-capable ships. Aircraft carriers may be classified according to the type of aircraft they carry and their operational assignments. Admiral Sir Mark Stanhope, former head of the Royal Navy, has said, "To put it simply, countries that aspire to strategic international influence have aircraft carriers".

As of , there are thirty-seven active aircraft carriers in the world within twelve navies. The United States Navy has 10 large nuclear-powered carriers (known as supercarriers, carrying up to 90 aircraft each), the largest carriers in the world; the total combined deckspace is over twice that of all other nations combined. As well as the supercarrier fleet, the US Navy has nine amphibious assault ships used primarily for helicopters (sometimes called helicopter carriers); these can also carry up to 25 vertical or short take-off and landing (V/STOL) fighter jets, and in some cases, are as large as some other nations' fixed-wing carriers.

Types of carrier
thumb|Brazilian aircraft carrier NAe São Paulo, foreground, and U.S. Navy carrier  during a combined training exercise.
thumb|, a supercarrier of the US Navy (left), sails alongside , a fleet carrier of the French Navy (right), both of which have the CATOBAR configuration.
thumb|right|, a light aircraft carrier of the Italian Navy.
thumb|right| of the Royal Navy, an amphibious assault ship/helicopter carrier.

Basic types
 Amphibious assault ship
 Anti-submarine warfare carrier
 Balloon carrier and balloon tenders
 Escort carrier
 Fleet carrier
 Flight deck cruiser
 Helicopter carrier
 Light aircraft carrier
 Sea Control Ship
 Seaplane tender and seaplane carriers
 Supercarrier
(note: some of the types listed here are not strictly defined as aircraft carriers by some sources)

By role
A fleet carrier is intended to operate with the main fleet and usually provides an offensive capability. These are the largest carriers capable of fast speeds. By comparison, escort carriers were developed to provide defense for convoys of ships. They were smaller and slower with lower numbers of aircraft carried. Most were built from mercantile hulls or, in the case of merchant aircraft carriers, were bulk cargo ships with a flight deck added on top. Light aircraft carriers were fast enough to operate with the main fleet but of smaller size with reduced aircraft capacity. Soviet aircraft carriers now in use by Russia are actually called heavy aviation cruisers; these ships, while sized in the range of large fleet carriers, were designed to deploy alone or with escorts, and provide both strong defensive weaponry and heavy offensive missiles equivalent to a guided missile cruiser, in addition to supporting fighters and helicopters.

By configuration
thumb| of the Indian Navy has the STOBAR configuration.

There are four main configurations of aircraft carrier in service in the world's navies, divided by the way that aircraft take off and land:
 Catapult-assisted take-off but arrested-recovery (CATOBAR): these carriers generally carry the largest, heaviest, and most heavily armed aircraft, although smaller CATOBAR carriers may have other limitations (weight capacity of aircraft elevator, etc.). Three nations currently operate carriers of this type: ten by the United States, and one each by France and Brazil for a total of twelve in service.
 Short take-off but arrested-recovery (STOBAR): these carriers are generally limited to carrying lighter fixed-wing aircraft with more limited payloads. STOBAR carrier air wings, such as the Sukhoi Su-33 and future Mikoyan MiG-29K wings of  are often geared primarily towards air superiority and fleet defense roles rather than strike/power projection tasks, which require heavier payloads (bombs and air-to-ground missiles). Currently, Russia, China, and India possess commissioned carriers of this type.
 Short take-off vertical-landing (STOVL): limited to carrying STOVL aircraft. STOVL aircraft, such as the Harrier Jump Jet family and Yakovlev Yak-38 generally have limited payloads, lower performance, and high fuel consumption when compared with conventional fixed-wing aircraft; however, a new generation of STOVL aircraft, currently consisting of the F-35B, has much improved performance. This type of aircraft carrier is currently in service with Italy. Spain also operates one amphibious assault ship as a STOVL aircraft carrier for three ships total in active carrier service; Thailand has one active STOVL carrier but it no longer has any operational STOVL aircraft in inventory. Some also count the nine US amphibious assault ships in their secondary light carrier role boosting the overall total to thirteen. The UK is building two 70,000 ton STOVL carriers, HMS Queen Elizabeth and HMS Prince of Wales, the largest warships ever built for the Royal Navy; the first is expected to be "initial maritime operational capability" by 2020.
 Helicopter carrier: Helicopter carriers have a similar appearance to other aircraft carriers and may support regular fixed wing operations. Some are designed for addition of, or may include, a ski jump ramp allowing for STOVL operations or may have an unused ski jump installed before retirement of STOVL aircraft and re-purposing. In the past, some conventional carriers were converted and called commando carriers by the Royal Navy. Some helicopter carriers with a resistant flight surface can operate STOVL jets. Currently the majority of helicopter carriers, but not all, are classified as amphibious assault ships, tasked with landing and supporting ground forces on enemy territory. The US has nine of this type, France and Japan three, Australia two, the UK one, the Republic of Korea (South Korea) one and Spain one. The US and Spain's amphibious assault ships operate STOVL jets in normal deployment.

By size
 Supercarrier
 Fleet carrier
 Light aircraft carrier
 Escort carrier

Hull type identification symbols
Several systems of identification symbol for aircraft carriers and related types of ship have been used. These include the pennant numbers used by the British Royal Navy and some Commonwealth countries, the US hull classification symbols also used by NATO and some other countries, and the Canadian hull classification symbols.

+ US hull classification symbols for aircraft carriers and related types Symbol  Designation CV  Generic aircraft carrier CVA  Attack carrier CVAN  Nuclear-powered attack carrier CVE  Escort carrier CVG  Flight deck cruiser (proposed) CVHA  Aircraft carrier, Helicopter Assault (retired) CVHE  Aircraft carrier, Helicopter, Escort (retired) CVL  Light aircraft carrier CVN  Nuclear-powered aircraft carrier CVS  Anti-submarine warfare carrier CVV  Aircraft Carrier, Medium (proposed) LHA  Landing Helicopter Assault, a type of Amphibious assault ship LHD  Landing Helicopter Dock, a type of Amphibious assault ship LPH  Landing Platform Helicopter, a type of Amphibious assault ship

History

Origins
thumb|right|The  conducted the world's first naval-launched air raids in 1914.

The 1903 advent of heavier-than-air fixed-wing aircraft was closely followed on 14 November 1910, by Eugene Burton Ely's first experimental take-off of a Curtiss pusher airplane from the deck of a United States Navy ship, the cruiser  anchored off Norfolk Navy Base in Virginia. Two months later, on 18 January 1911, Ely landed his Curtiss pusher airplane on a platform on the armored cruiser USS Pennsylvania anchored in San Francisco Bay. On 9 May 1912, the first airplane take-off from a ship underway was made from the deck of the British Royal Navy's . Seaplane tender support ships came next, with the French  of 1911. Early in World War I, the Imperial Japanese Navy ship  conducted the world's first successful ship-launched air raid: on 6 September 1914, a Farman aircraft launched by Wakamiya attacked the Austro-Hungarian cruiser  and the German gunboat Jaguar in Kiaochow Bay off Tsingtao; neither was hit. The first carrier-launched airstrike was the Tondern Raid in July 1918. Seven Sopwith Camels launched from the converted battlecruiser  damaged the German airbase at Tønder and destroyed two zeppelin airships.Probert, p. 46

thumb|Aerial view of  of the Imperial Japanese Navy as completed in December 1922.
The development of flattop vessels produced the first large fleet ships. In 1918,  became the world's first carrier capable of launching and recovering naval aircraft. As a result of the Washington Naval Treaty of 1922, which limited the construction of new heavy surface combat ships, most early aircraft carriers were conversions of ships that were laid down (or had served) as different ship types: cargo ships, cruisers, battlecruisers, or battleships. These conversions gave rise to the US s (1927), Japanese , and British . Specialist carrier evolution was well underway, with several navies ordering and building warships that were purposefully designed to function as aircraft carriers by the mid-1920s, resulting in the commissioning of ships such as IJN  (1922),  (1924), and  (1927). During World War II, these ships would become known as fleet carriers.

World War II

thumb|Attack on carrier , 19 March 1945. The casualties included 724 killed. thumb|, the most decorated US ship of World War II.

The aircraft carrier dramatically changed naval combat in World War II, because air power was becoming a significant factor in warfare. The advent of aircraft as focal weapons was driven by the superior range, flexibility, and effectiveness of carrier-launched aircraft. They had greater range and precision than naval guns, making them highly effective. The versatility of the carrier was demonstrated in November 1940, when  launched a long-range strike on the Italian fleet at their base in Taranto, signalling the beginning of the effective and highly mobile aircraft strikes. This operation incapacitated three of the six battleships at a cost of two torpedo bombers. World War II in the Pacific Ocean involved clashes between aircraft carrier fleets. The 7 December 1941 Japanese surprise attack on Pearl Harbor was a clear illustration of the power projection capability afforded by a large force of modern carriers. Concentrating six carriers in a single unit turned naval history about, as no other nation had fielded anything comparable. However, the vulnerability of carriers compared to traditional battleships when forced into a gun-range encounter was quickly illustrated by the sinking of  by German battleships during the Norwegian campaign in 1940.

This new-found importance of naval aviation forced nations to create a number of carriers, in efforts to provide air superiority cover for every major fleet in order to ward off enemy aircraft. This extensive usage led to the development and construction of 'light' carriers. Escort aircraft carriers, such as , were sometimes purpose-built but most were converted from merchant ships as a stop-gap measure to provide anti-submarine air support for convoys and amphibious invasions. Following this concept, light aircraft carriers built by the US, such as , represented a larger, more "militarized" version of the escort carrier. Although with similar complement to escort carriers, they had the advantage of speed from their converted cruiser hulls. The UK 1942 Design Light Fleet Carrier was designed for building quickly by civilian shipyards and with an expected service life of about 3 years. They served the Royal Navy during the war and was the hull design chosen for nearly all aircraft carrier equipped navies after the war until the 1980s. Emergencies also spurred the creation or conversion of highly unconventional aircraft carriers. CAM ships, were cargo-carrying merchant ships that could launch (but not retrieve) a single fighter aircraft from a catapult to defend the convoy from long range German aircraft.

Postwar era
thumb|USS Tripoli, a US Navy Iwo Jima-class helicopter carrier
thumb|, the world's first nuclear-powered carrier commissioned in 1961.

Before World War II, international naval treaties of 1922, 1930, and 1936 limited the size of capital ships including carriers.  Since World War II, aircraft carrier designs have increased in size to accommodate a steady increase in aircraft size. The large, modern  of US carriers has a displacement nearly four times that of the World War II–era , yet its complement of aircraft is roughly the same—a consequence of the steadily increasing size and weight of military aircraft over the years. Today's aircraft carriers are so expensive that nations which operate them risk significant political, economic, and military impact if a carrier is lost, or even used in conflict.

Modern navies that operate such aircraft carriers treat them as the capital ship of the fleet, a role previously held by the battleship. This change took place during World War II in response to air power becoming a significant factor in warfare, driven by the superior range, flexibility and effectiveness of carrier-launched aircraft. Following the war, carrier operations continued to increase in size and importance. Supercarriers, displacing 75,000 tonnes or greater, have become the pinnacle of carrier development. Some are powered by nuclear reactors and form the core of a fleet designed to operate far from home. Amphibious assault ships, such as  and , serve the purpose of carrying and landing Marines, and operate a large contingent of helicopters for that purpose. Also known as "commando carriers"A number of British conversions of light fleet carriers to helicopter operations were known as commando carriers, though they did not operate landing craft or "helicopter carriers", many have the capability to operate VSTOL aircraft.

Lacking the firepower of other warships, carriers by themselves are considered vulnerable to attack by other ships, aircraft, submarines, or missiles. Therefore, an aircraft carrier is generally accompanied by a number of other ships to provide protection for the relatively unwieldy carrier, to carry supplies and perform other support services, and to provide additional offensive capabilities. The resulting group of ships is often termed a battle group, carrier group, or carrier battle group.

There is a view that modern anti-ship weapons systems, such as torpedoes and missiles, have made aircraft carriers obsolete as too vulnerable for modern combat.  On the other hand, the threatening role of aircraft carriers has a place in modern asymmetric warfare, like the gunboat diplomacy of the past. Furthermore, aircraft carriers facilitate quick and precise projections of overwhelming military power into such local and regional conflicts.

Aircraft carriers in service
thumb|right|US Navy personnel direct an aircraft onto a catapult aboard the Nimitz-class aircraft carrier USS John C. Stennis.

Most navies operate only one or two aircraft carriers, if any. The USA is a notable exception, with 10 super carriers and 9 amphibious assault ships in service.

A total of 20 fleet carriers are in active service with ten navies. Additionally, the navies of Australia, Brazil, China, France, India, Italy, Japan, Russia, South Korea, Spain, Thailand and the United States also operate ships capable of carrying and operating multiple helicopters and STOVL aircraft.

CATOBAR types are operated by Brazil, France and especially the USA, which has ten in service.
STOBAR type are operated by China, India and Russia.
STOVL types are operated by India, Italy, Spain and the USA.

Among helicopter-only types:
ASW ships are operated by Japan.
An offshore helicopter support ship is operated by Thailand.
Amphibious assault ships are operated by Australia, France, the Republic of Korea, the United Kingdom and especially the USA, which has nine in service.

Future of aircraft carriers
Many aircraft carriers and related types are planned, under construction, or undergoing commissioning activity.

 Australia 
The Royal Australian Navy is in the process of procuring two Canberra-class LHDs, the first of which was commissioned in November 2015, while the second is expected to enter service in 2016. The ships will be the largest in Australian naval history. Their primary roles are to embark, transport and deploy an embarked force and to carry out or support humanitarian assistance missions. The LHD is capable of launching multiple helicopters at one time while maintaining an amphibious capability of 1,000 troops and their supporting vehicles (tanks, armoured personnel carriers etc.). The Australian Defence Minister has publicly raised the possibility of procuring F-35B STOVL aircraft for the carrier, stating that it "has been on the table since day one" and stating the LHDs are "STOVL capable".

 India 
thumb|, an indigenously built aircraft carrier (IAC) was undocked on 10 June 2015.
thumb| just after her launch.

In December 2009, then Indian Navy chief Admiral Nirmal Kumar Verma said at his maiden Navy Week press conference that concepts currently being examined by the Directorate of Naval Design for the second indigenous aircraft carrier (IAC-II), are for a conventionally powered carrier displacing over 50,000 tons and equipped with steam catapults (rather than the ski-jump on the Gorshkov/Vikramaditya and the IAC-1) to launch fourth-generation aircraft.In August 2013, Vice Admiral RK Dhowan, while talking about the detailed study underway on the IAC-II project, said that nuclear propulsion was also being considered. The Indian Navy also evaluated the Electromagnetic Aircraft Launch System (EMALS), which is being used by the US Navy in their latest s. General Atomics, the developer of the EMALS, was cleared by the US government to give a technical demonstration to Indian Navy officers, who were impressed by the new capabilities of the system. The EMALS enables launching varied aircraft including unmanned combat air vehicles (UCAV). The Indian Navy's goal is to have a total of three aircraft carriers in service, with two fully operational carriers and the third in refit.

 Japan 
In August 2013, a launching ceremony for Japan's largest military ship since World War II was held in Yokohama. The , 19,500-ton flattop  was deployed in March 2015. The ship is able to carry up to 14 helicopters; however, only seven ASW helicopters and two SAR helicopters were planned for the initial aircraft complement. For other operations, up to 400 troops and fifty 3.5 ton trucks (or equivalent equipment) can also be carried. The flight deck has five helicopter landing spots that allow simultaneous landings or take-offs. The ship is equipped with two Phalanx CIWS and two SeaRAM for its defense.

 Russia 
Speaking in St. Petersburg, Russia, on 30 June 2011, the head of Russia's United Shipbuilding Corporation said his company expected to begin design work for a new carrier in 2016, with a goal of beginning construction in 2018 and having the carrier achieve initial operational capability by 2023. Several months later, on 3 November 2011, the Russian newspaper Izvestiya reported that the naval building plan now included the construction of a new shipyard capable of building large hull ships, after which Moscow will build two (80,000 tons full load each) nuclear-powered aircraft carriers by 2027. The spokesperson said one carrier would be assigned to the Russian Navy's Northern Fleet at Murmansk, and the second would be stationed with the Pacific Fleet at Vladivostok.

 South Korea 
The Republic of Korea Navy (South Korea) believes it can deploy two light aircraft carriers by 2036 and expand its blue-water force to cope with the rapid naval buildups of China and Japan, according to a Navy source.

 United Kingdom 
thumb|right|, the lead  supercarrier.

The British Royal Navy is constructing two new larger STOVL aircraft carriers, the , to replace the three  carriers. The  and  will be able to operate up to 40 aircraft in peacetime, with a tailored group of up to 50, and will have a displacement of 70,600 tonnes. The ships are due to become operational from 2020. Their primary aircraft complement will be made up of F-35B Lightning IIs, and their ship's company will number around 680, with the total complement rising to about 1,600 when the air group is embarked. Defensive weapons will include the Phalanx CIWS for anti-aircraft and anti-missile defence, 30 mm Automated Small Calibre Guns, and miniguns for use against fast attack craft.Royal Navy - Queen Elizabeth Class - Facts and Figures The two ships will be the largest warships ever built for the Royal Navy.

 United States 
The current US fleet of  carriers will be followed into service (and in some cases replaced) by the ten-ship . The Ford-class ships will be more automated in an effort to reduce the amount of funding required to staff, maintain, and operate its supercarriers. The main new features are implementation of Electromagnetic Aircraft Launch System (EMALS) (which replace the old steam catapults) and unmanned aerial vehicles. With the deactivation of  in December 2012 (decommissioning scheduled for 2016), the US fleet comprises 10 active supercarriers. On 24 July 2007, the House Armed Services Seapower subcommittee recommended seven or eight new carriers (one every four years). However, the debate has deepened over budgeting for the $12–14.5 billion (plus $12 billion for development and research) for the 100,000 ton Gerald R. Ford-class carrier (estimated service 2016) compared to the smaller $2 billion 45,000 ton s able to deploy squadrons of F-35B of which one is already active, another is under construction, and nine more are planned.

Description

Structure
thumb|right|STOVL Harriers preparing to takeoff from CATOBAR carrier, 

Carriers are large and long ships, although there is a high degree of variation depending on their intended role and aircraft complement. The size of the carrier has varied over history and among navies, to cater to the various roles that global climates have demanded from naval aviation.

Regardless of size, the ship itself must house their complement of aircraft, with space for launching, storing, and maintaining them. Space is also required for the large crew, supplies (food, munitions, fuel, engineering parts), and propulsion. US supercarriers are notable for having nuclear reactors powering their systems and propulsion. This makes the carrier reasonably tall.

The top of the carrier is the flight deck, where aircraft are launched and recovered. On the starboard side of this is the island, where air-traffic control and the bridge are located.

The constraints of constructing a flight deck affect the role of a given carrier strongly, as they influence the weight, type, and configuration of the aircraft that may be launched. For example, assisted launch mechanisms are used primarily for heavy aircraft, especially those loaded with air-to-ground weapons. CATOBAR is most commonly used on USN supercarriers as it allows the deployment of heavy jets with full loadouts, especially on ground-attack missions. STOVL is used by other navies because it is cheaper to operate and still provides good deployment capability for fighter aircraft.

thumb|The first carrier landing and take-off of a jet aircraft: Eric "Winkle" Brown landing on  in 1945.
Due to the busy nature of the flight deck, only 20 or so aircraft may be on it at any one time. A hangar storage several decks below the flight deck is where most aircraft are kept, and aircraft are taken from the lower storage decks to the flight deck through the use of an elevator. The hangar is usually quite large and can take up several decks of vertical space.How Aircraft Carriers Work, How Stuff Works, by Tom Harris – http://science.howstuffworks.com/aircraft-carrier6.htm Accessed 5 October 2013

Munitions are commonly stored on the lower decks because they are highly explosive should the compartment they are in be breached. Usually this is below the water line so that the area can be flooded in case of emergency.

Flight deck

thumb|Catapult launches aboard .
thumb| Expansive Flight Deck of  at night showing the ski-jump ramp used for STOBAR configuration
As "runways at sea", aircraft carriers have a flat-top flight deck, which launches and recovers aircraft. Aircraft launch forward, into the wind, and are recovered from astern. The flight deck is where the most notable differences between a carrier and a land runway are found. Creating such a surface at sea poses constraints on the carrier – for example, the fact that it is a ship means that a full-length runway would be costly to construct and maintain. This affects take-off procedure, as a shorter runway length of the deck requires that aircraft accelerate more quickly to gain lift. This either requires a thrust boost, a vertical component to its velocity, or a reduced take-off load (to lower mass). The differing types of deck configuration, as above, influence the structure of the flight deck. The form of launch assistance a carrier provides is strongly related to the types of aircraft embarked and the design of the carrier itself.

There are two main philosophies in order to keep the deck short: add thrust to the aircraft, such as using a Catapult Assisted Take-Off (CATO-); and changing the direction of the airplanes' thrust, as in Vertical and/or Short Take-Off (V/STO-). Each method has advantages and disadvantages of its own:
Catapult Assisted Take-Off But Arrested Recovery (CATOBAR): A steam-powered catapult is connected to the aircraft, and is used to accelerate conventional aircraft to a safe flying speed. By the end of the catapult stroke, the aircraft is airborne and further propulsion is provided by its own engines. This is the most expensive method as it requires complex machinery to be installed under the flight deck, but allows for even heavily loaded aircraft to take off.
Short take-off but arrested recovery (STOBAR) depends on increasing the net lift on the aircraft. Aircraft do not require catapult assistance for take off; instead on nearly all ships of this type an upwards vector is provided by a ski-jump at the forward end of the flight deck, often combined with thrust vectoring by the aircraft. Alternatively, by reducing the fuel and weapon load, an aircraft is able to reach faster speeds and generate more upwards lift and launch without a ski-jump or catapult.
Short take-off vertical-landing (STOVL): On aircraft carriers, non-catapult-assisted, fixed-wing short takeoffs are accomplished with the use of thrust vectoring, which may also be used in conjunction with a runway "ski-jump". Use of STOVL tends to allow aircraft to carry a larger payload as compared to during VTOL use, while still only requiring a short runway. The most famous examples are the Hawker Siddeley Harrier and the Sea Harrier. Although technically VTOL aircraft, they are operationally STOVL aircraft due to the extra weight carried at take-off for fuel and armaments. The same is true of the F-35B Lightning II, which demonstrated VTOL capability in test flights but is operationally STOVL.
Vertical take-off and landing (VTOL): Aircraft are specifically designed for the purpose of using very high degrees of thrust vectoring (e.g. if the thrust to weight-force ratio is greater than 1, it can take off vertically), but are usually slower than conventionally propelled aircraft.

On the recovery side of the flight deck, the adaptation to the aircraft loadout is mirrored. Non-VTOL or conventional aircraft cannot decelerate on their own, and almost all carriers using them must have arrested-recovery systems (-BAR, e.g. CATOBAR or STOBAR) to recover their aircraft. Aircraft that are landing extend a tailhook that catches on arrestor wires stretched across the deck to bring themselves to a stop in a short distance. Post-WWII Royal Navy research on safer CATOBAR recovery eventually led to universal adoption of a landing area angled off axis to allow aircraft who missed the arresting wires to "bolt" and safely return to flight for another landing attempt rather than crashing into aircraft on the forward deck.

If the aircraft are VTOL-capable or helicopters, they do not need to decelerate and hence there is no such need. The arrested-recovery system has used an angled deck since the 1950s because, in case the aircraft does not catch the arresting wire, the short deck allows easier take off by reducing the number of objects between the aircraft and the end of the runway. It also has the advantage of separating the recovery operation area from the launch area. Helicopters and aircraft capable of vertical or short take-off and landing (V/STOL) usually recover by coming abreast the carrier on the port side and then using their hover capability to move over the flight deck and land vertically without the need for arresting gear.

Staff and Deck Operations
thumb|F/A-18 landing video

Carriers steam at speed, up to  into the wind during flight deck operations to increase wind speed over the deck to a safe minimum. This increase in effective wind speed provides a higher launch airspeed for aircraft at the end of the catapult stroke or ski-jump, as well as making recovery safer by reducing the difference between the relative speeds of the aircraft and ship.

Since the early 1950s on conventional carriers it has been the practice to recover aircraft at an angle to port of the axial line of the ship. The primary function of this angled deck is to allow aircraft that miss the arresting wires, referred to as a bolter, to become airborne again without the risk of hitting aircraft parked forward. The angled deck allows the installation of one or two "waist" catapults in addition to the two bow cats. An angled deck also improves launch and recovery cycle flexibility with the option of simultaneous launching and recovery of aircraft.

Conventional ("tailhook") aircraft rely upon a landing signal officer (LSO, radio call sign paddles) to monitor the aircraft's approach, visually gauge glideslope, attitude, and airspeed, and transmit that data to the pilot. Before the angled deck emerged in the 1950s, LSOs used colored paddles to signal corrections to the pilot (hence the nickname). From the late 1950s onward, visual landing aids such as Optical Landing System have provided information on proper glide slope, but LSOs still transmit voice calls to approaching pilots by radio.

thumb|left||F/A-18 Hornets on the flight deck of the   
Key personnel involved in the flight deck include the shooters, the handler, and the air boss. Shooters are naval aviators or Naval Flight Officers and are responsible for launching aircraft. The handler works just inside the island from the flight deck and is responsible for the movement of aircraft before launching and after recovery. The "air boss" (usually a commander) occupies the top bridge (Primary Flight Control, also called primary or the tower) and has the overall responsibility for controlling launch, recovery and "those aircraft in the air near the ship, and the movement of planes on the flight deck, which itself resembles a well-choreographed ballet." The captain of the ship spends most of his time one level below primary on the Navigation Bridge. Below this is the Flag Bridge, designated for the embarked admiral and his staff.

To facilitate working on the flight deck of a U.S. aircraft carrier, the sailors wear colored shirts that designate their responsibilities. There are at least seven different colors worn by flight deck personnel for modern United States Navy carrier air operations. Carrier operations of other nations use similar color schemes.

Deck structures
thumb|Island control structure of 

The superstructure of a carrier (such as the bridge, flight control tower) are concentrated in a relatively small area called an island, a feature pioneered on the  in 1923. While the island is usually built on the starboard side of the fight deck, the Japanese aircraft carriers  and  had their islands built on the port side. Very few carriers have been designed or built without an island. The flush deck configuration proved to have significant drawbacks, primary of which was management of the exhaust from the power plant. Fumes coming across the deck were a major issue in . In addition, lack of an island meant difficulties managing the flight deck, performing air traffic control, a lack of radar housing placements and problems with navigating and controlling the ship itself.

Another deck structure that can be seen is a ski-jump ramp at the forward end of the flight deck. This was first developed to help launch STOVL aircraft take off at far higher weights than is possible with a vertical or rolling takeoff on flat decks. Originally developed by the Royal Navy, it since has been adopted by many navies for smaller carriers. A ski-jump ramp works by converting some of the forward rolling movement of the aircraft into vertical velocity and is sometimes combined with the aiming of jet thrust partly downwards. This allows heavily loaded and fueled aircraft a few more precious seconds to attain sufficient air velocity and lift to sustain normal flight. Without a ski-jump launching fully loaded and fueled aircraft such as the Harrier would not be possible on a smaller flat deck ship before either stalling out or crashing directly into the sea.

thumb|left|Ski-jump on Royal Navy carrier 
Although STOVL aircraft are capable of taking off vertically from a spot on the deck, using the ramp and a running start is far more fuel efficient and permits a heavier launch weight. As catapults are unnecessary, carriers with this arrangement reduce weight, complexity, and space needed for complex steam or electromagnetic launching equipment, vertical landing aircraft also remove the need for arresting cables and related hardware. Russian, Chinese, and future Indian carriers include a ski-jump ramp for launching lightly loaded conventional fighter aircraft but recover using traditional carrier arresting cables and a tailhook on their aircraft.

The disadvantage of the ski-jump is the penalty it exacts on aircraft size, payload, and fuel load (and thus range); heavily laden aircraft can not launch using a ski-jump because their high loaded weight requires either a longer takeoff roll than is possible on a carrier deck, or assistance from a catapult or JATO rocket. For example, the Russian Su-33 is only able to launch from the carrier  with a minimal armament and fuel load. Another disadvantage is on mixed flight deck operations where helicopters are also present such as a US Landing Helicopter Dock or Landing Helicopter Assault amphibious assault ship a ski jump is not included as this would eliminate one or more helicopter landing areas, this flat deck limits the loading of Harriers but is somewhat mitigated by the longer rolling start provided by a long flight deck compared to many STOVL carriers.

National fleets

thumb|right|upright=1.35|Chart of aircraft and helicopter carriers from around the world

A total of 20 fleet carriers are in active service with ten navies. Additionally, the navies of Australia, Brazil, China, France, India, Italy, Japan, South Korea, Spain, Thailand and the United States also operate ships capable of carrying and operating multiple helicopters and STOVL aircraft.

Australia
thumb|right|, a 

Current
The  of landing helicopter docks, based on the Spanish vessel , is composed of two ships. The class was built by Navantia and BAE Systems Australia; and  are the largest ship ever built for the Royal Australian Navy. 

Canberra underwent sea trials in late 2013 and was commissioned in 2014. Canberras sister ship, , was commissioned in December 2015. The Australian version retains the ski-ramp from the Juan Carlos I design, although the RAN has not acquired carrier-based fixed-wing aircraft.

Brazil
thumb|right| of the Brazilian Navy 

Current
One CATOBAR carrier:  is a  currently in service with the Brazilian Navy. São Paulo was first commissioned in 1963 by the French Navy as  and was transferred in 2000 to Brazil, where she became the new flagship of the Brazilian Navy. During the period from 2005 to 2010, São Paulo underwent extensive modernization. At the end of 2010, sea trials began, and  São Paulo had been evaluated by the CIASA (Inspection Commission and Training Advisory). She was expected to rejoin the fleet in late 2013, but suffered another major fire in 2012..

China
thumb|China's first aircraft carrier  under refit in Dalian Shipbuilding Industry Company

Current
One STOBAR carrier:  was originally built as the 57,000 tonne Soviet  carrier Varyag and was later purchased as a stripped hulk by China in 1998 on the pretext of use as a floating casino, then partially rebuilt and towed to China for completion. Liaoning was commissioned on 25 September 2012, and began service for testing and training. On 24 or 25 November 2012, Liaoning successfully launched and recovered several Shenyang J-15 jet fighter aircraft.  She is classified as a training ship, intended to allow the navy to practice with carrier usage. On 26 December 2012, the People's Daily reported that it will take four to five years for Liaoning to reach full capacity, mainly due to training and coordination which will take significant amount of time for Chinese PLA Navy to complete as this is the first aircraft carrier in their possession.  As it is a training ship, Liaoning is not assigned to any of China's operation fleets.[]

Future
In December 2013, China's Central Military Commission told Duowei News it planned to commission two Liaoning-pattern aircraft carriers by 2020, designated as Type 001A. Contracts have been awarded to China Shipbuilding Industry Corporation to build the two carriers. The cost is projected to be US$9 billion.

Egypt
thumb|right|Gamal Abdel Nasser LHD docked at Saint-Nazaire, April 2016

Current
Egypt signed a contract with French shipbuilder DCNS to buy two  helicopter carriers for approximately 950 million euros. The two ships were originally destined for Russia, but the deal was canceled by France due to Russian involvement in Ukraine.

On 2 June 2016, Egypt received the first of two helicopter carriers acquired in October 2015, the Landing Helicopter Dock Gamal Abdel Nasser. The flag transfer ceremony took place in the presence of Egyptian and French Navies’ Chiefs of Staff, Chairman and Chief Executive Officers of both DCNS and STX France, and senior Egyptian and French officials. On 16 September 2016, DCNS delivered the second of two helicopter carriers, the Landing Helicopter Dock Anwar El Sadat which also participated in a joint exercise with the French Navy before arriving at its home port of Alexandria.

Egypt is considered the first and only country in Africa and the Middle East to possess an aircraft carrier of such type.

France
thumb|right|The aircraft carrier  of the French Navy

Current
1 CATOBAR carrier:  is a 42,000 tonne nuclear-powered aircraft carrier, commissioned in 2001 and is the flagship of the French Navy (Marine Nationale). The ship carries a complement of Dassault Rafale M and  E‑2C Hawkeye aircraft, EC725 Caracal and AS532 Cougar helicopters for combat search and rescue, as well as modern electronics and Aster missiles. It is a CATOBAR-type carrier that uses two 75 m C13‑3 steam catapults of a shorter version of the catapult system installed on the U.S.  carriers, one catapult at the bow and one across the front of the landing area.

3 amphibious assault ships: , 21,500 tonne full deck amphibious assault ships with hospital and well deck.

India
thumb|Indian Navy's aircraft carriers  and  in 2014

Current
1 STOBAR carrier: , 45,400 tonnes, modified Kiev class. The carrier was purchased by India on 20 January 2004 after years of negotiations at a final price of $2.35 billion. The ship successfully completed her sea trials in July 2013 and aviation trials in September 2013. She was formally commissioned on 16 November 2013 at a ceremony held at Severodvinsk, Russia.

Recently ,  previously known as the Royal Navy's , was retired from active service. India currently has one active aircraft carrier.

Future
India started the construction of a 40,000-tonne,   aircraft carrier in 2009.  The new carrier will operate MiG-29K and naval HAL Tejas aircraft along with the Indian-made helicopter HAL Dhruv. The ship will be powered by four gas-turbine engines and will have a range of , carrying 160 officers, 1,400 sailors, and 30 aircraft. The carrier is being constructed by Cochin Shipyard. The ship was launched in August 2013 and is scheduled for commissioning in 2018.

A second Vikrant-class carrier  with a displacement of over 65,000 tons is planned and likely to be nuclear-powered with CATOBAR system to launch and recover heavier aircraft and unmanned combat aircraft. The project is in the design phase as of April 2015.

Italy
thumb|right|The aircraft carrier  of the Italian Navy

Current
2 STOVL carriers:
 : 14,000 tonne Italian STOVL carrier, commissioned in 1985.
 : 27,000 tonne Italian STOVL carrier designed and built with secondary amphibious assault facilities, commissioned in 2008.

Japan
thumb|Helicopter carrier Hyūga

Current
3 helicopter carriers:

2 s - 19,000 ton (full load) anti-submarine warfare carriers with enhanced command-and-control capabilities allowing them to serve as fleet flagships.

1  - , 19,500-ton (27,000 tons full load) helicopter carrier, launched August 2013 and commissioned March 2015. This is the largest military ship Japan has had since World War II.

Future
Izumos sister ship, Kaga, is under construction and is projected to commission in 2017.

Russia
thumb|

Current
1 STOBAR carrier: Admiral Flota Sovetskovo Soyuza Kuznetsov: 55,000 tonne  STOBAR aircraft carrier. Launched in 1985 as Tbilisi, renamed and operational from 1995. Without catapults she can launch and recover lightly fueled naval fighters for air defense or anti-ship missions but not heavy conventional bombing strikes.  Officially designated an aircraft carrying cruiser, she is unique in carrying a heavy cruiser's complement of defensive weapons and large P-700 Granit offensive missiles. The P-700 systems will be removed in the coming refit to enlarge her below decks aviation facilities as well as upgrading her defensive systems.

Future
The Russian Government just recently gave the green light for the construction of the Shtorm-class aircraft carrier. This carrier will be a hybrid of CATOBAR and STOBAR, given the fact that it utilizes both systems of launching aircraft. The carrier is expected to cost between $1.8 billion and $5.63 billion. Once commissioned, she will replace Admiral Kuznetsov.

South Korea
thumb|right|, a  of the Republic of Korea Navy.

Current
One  18,860 ton full deck amphibious assault ship with hospital and well deck and facilities to serve as fleet flagship.

Future
South Korea believes it can procure 2 light aircraft carriers by 2036, which will help make the ROKN a blue water navy.

Spain

Current
1 Landing helicopter dock used as a STOVL carrier: : 27,000 tonne, Specially designed multipurpose strategic projection ship which can operate as an amphibious assault ship or STOVL carrier depending on mission requirement, has full facilities for both functions including a ski jump ramp, well deck, and vehicle storage area which can be used as additional hangar space, launched in 2008, commissioned 30 September 2010.

Thailand
thumb|right|The aircraft carrier  of the Royal Thai Navy.

Current
One offshore helicopter support ship:  helicopter carrier: 11,400 tonne STOVL carrier based on Spanish  design. Commissioned in 1997. The AV-8S Matador/Harrier STOVL fighter wing, mostly inoperable by 1999,Carpenter & Wiencek, Asian Security Handbook 2000, p. 302. was retired from service without replacement in 2006. Ship now used for royal transport, helicopter operations, and as a disaster relief platform.

United Kingdom

Current
One amphibious assault ship: . A 21,750 ton full deck amphibious assault ship based on the Invincible-class aircraft carrier hull but without facilities for fixed wing aviation.

Future
The Royal Navy is constructing two new larger STOVL aircraft carriers, the , to replace the three now retired  carriers. The ships are  and . They will be able to operate up to 40 aircraft on peace time operations with a tailored group of up to 50, and will have a displacement of 70,600 tonnes. HMS Queen Elizabeth is projected to commission in 2017 followed by Prince of Wales in about 2020. The ships are due to become operational starting in 2020. Their primary aircraft complement will be made up of F-35B Lightning IIs, and their ship's company will number around 680 with the total complement rising to about 1600 when the air group is embarked. The two ships will be the largest warships ever built for the Royal Navy.

United States
thumb|Amphibious assault ship 

Current
10 CATOBAR carriers: : ten 101,000 ton nuclear-powered supercarriers, the first of which was commissioned in 1975. A Nimitz-class carrier is powered by two nuclear reactors providing steam to four steam turbines and is  long.  The decommissioned supercarrier  is being held in reserve until the first of the new  comes into service in 2017.WWAY News Channel 3 "USS Kitty Hawk will have to stay in reserve" published 4 December 2008After decades of faithful service, the USS Kitty Hawk is awaiting her fate while in reserve status with the US Navy.

Nine Amphibious assault ships:
  a class of 45,000 ton amphibious assault ships, although the lead ship in this class does not have a well deck. One ship in service out of a planned 12 ships. Ships of this class can have a secondary mission as a light carrier with 20 AV-8B Harrier II, and in the future the F-35B Lightning II aircraft after unloading their Marine expeditionary unit.
  a class of eight 41,000 ton amphibious assault ships, members of this class have been used in wartime in their secondary mission as light carriers with 20 to 25 AV-8Bs after unloading their Marine expeditionary unit.

thumb|, a 

Future
The current US fleet of Nimitz-class carriers will be followed into service (and in some cases replaced) by the . It is expected that the ships will be more automated in an effort to reduce the amount of funding required to maintain and operate the vessels. The main new features are implementation of Electromagnetic Aircraft Launch System (EMALS) (which replace the old steam catapults) and unmanned aerial vehicles.

With the deactivation of  in December 2012, the U.S. fleet comprises 10 supercarriers. The House Armed Services Seapower subcommittee on 24 July 2007, recommended seven or maybe eight new carriers (one every four years). However, the debate has deepened over budgeting for the $12–14.5 billion (plus $12 billion for development and research) for the 100,000 ton Gerald R. Ford-class carrier (estimated service 2016) compared to the smaller $2 billion 45,000 ton s, which are able to deploy squadrons of F-35Bs. The first of this class, , is now in active service with another, , under construction and 9 more are planned.

Aircraft Carriers in preservation

Current museum carriers
A few aircraft carriers have been preserved as museum ships. They are:

  in Mount Pleasant, South Carolina
  in New York City, New York
  in Alameda, California
  in Corpus Christi, Texas
  in San Diego, California.
 , formerly  will be preserved in Visakhapatnam, Andhra Pradesh 
  in Tianjin, China
  in Nantong, China

Future museum carriers
  has a preservation campaign to bring her to Long Beach, California. Kitty Hawk is to be kept in reserve until  is commissioned in 2020. 
  has a preservation campaign to bring her to Newport, Rhode Island. At the moment, they are just waiting for the US Navy's final approval. 
  has a preservation campaign to bring her to the West Coast of the United States as the world's first amphibious assault ship museum. 

Former museum carriers
  was slated for preservation in New Orleans, Louisiana. Throughout most of the 1990's she was docked in New Orleans waiting for the preservation society to finalize a permanent berth. During this time she was designated a national historic landmark by the US Government. However, the preservation society was unable to pay creditors and an embezzlement scandal also rocked the society, stripping the group of its funds. As a result, her landmark status was withdrawn and sold for scrap in 1999. 
  was on display in Mumbai, India from 1997 to 2012. She sold for scrap after her condition deteriorated and failing to find an industrial partner. 

See also

Airborne aircraft carrier
Carrier-based aircraft
Lily and Clover
Merchant aircraft carrier
Mobile offshore base
Project Habakkuk
Seadrome
Submarine aircraft carrier
Timeline for aircraft carrier service
Unsinkable aircraft carrier

Related lists

 List of aircraft carriers
 List of aircraft carriers by country 
 List of aircraft carriers in service
 List of aircraft carriers by configuration
 List of sunken aircraft carriers
 List of Canadian aircraft carriers
 List of aircraft carriers of the People's Liberation Army Navy 
 List of current French aircraft carriers
 List of German aircraft carriers
 List of aircraft carriers of the Indian Navy
 List of Italian aircraft carriers
 List of aircraft carriers of the Japanese Navy
 List of aircraft carriers of Russia and the Soviet Union
 List of active Spanish aircraft carriers
 List of aircraft carriers of the Royal Navy
 List of seaplane carriers of the Royal Navy
 List of escort aircraft carriers of the Royal Navy
 List of aircraft carriers of the United States Navy
 List of aircraft carrier classes of the United States Navy
 List of escort aircraft carriers of the United States Navy
 List of amphibious warfare ships
 List of carrier-based aircraft
 Number of warships in service worldwide
 List of ships of the Second World War
 List of aircraft carriers of the Second World War

References

Further reading

 Ader, Clement. Military Aviation, 1909, Edited and translated by Lee Kennett, Air University Press, Maxwell Air Force Base, Alabama, 2003, ISBN 978-1-58566-118-3.
 Francillon, René J, Tonkin Gulf Yacht Club US Carrier Operations off Vietnam, (1988) ISBN 978-0-87021-696-1.
 Friedman, Norman, U.S. Aircraft Carriers: an Illustrated Design History, Naval Institute Press, 1983. ISBN 978-0-87021-739-5.
 Hone, Thomas C., Norman Friedman, and Mark D. Mandeles. "Innovation in Carrier Aviation," Naval War College Newport Papers (no. 37, 2011), 1–171.
 Melhorn, Charles M. Two-Block Fox: The Rise of the Aircraft Carrier, 1911–1929 (Naval Institute Press, 1974)
 Nordeen, Lon, Air Warfare in the Missile Age, (1985) ISBN 978-1-58834-083-2
 
 
 Till, Geoffrey. "Adopting the Aircraft Carrier: The British, Japanese, and American Case Studies" in Murray, Williamson; Millet, Allan R, eds. (1996). Military Innovation in the Interwar Period. Cambridge University Press.
 Trimble, William F. Admiral William A. Moffett: Architect of Naval Aviation (Smithsonian Institution Press, 1994)
 Wadle, Ryan David. United States navy fleet problems and the development of carrier aviation, 1929–1933 PhD dissertation Texas A&M University, 2005. online

External links

 Future Aircraft Carrier: UK. Armed Forces International
 Aircraft carriers of the USN
 Info about flight deck crew, arresting cables, catapults
 How Stuff Works—Aircraft Carriers
 Haze Gray & Underway, World Aircraft Carrier Lists comprehensive and detailed listings of all the world's aircraft carriers and seaplane tenders from 1913 to 2001, with photo gallery.
 Ships That Mother Seaplanes: craft of the "hush-hush" fleet may play a part in first trans-Atlantic flight. Popular Science monthly, February 1919, page 80, on Google Books.

 
Category:Ship types
Category:Articles containing video clips