Aircraft carrier
thumb|upright=1.35|Four modern aircraft carriers of various types—, Charles de Gaulle (French Navy), , 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. 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 fighters, strike aircraft, helicopters, and other types of aircraft. While heavier aircraft such as fixed-wing gunships and bombers have been launched from aircraft carriers, it is currently not possible to land them. By its diplomatic and tactical power, its mobility, its autonomy and the variety of its means, the aircraft carrier is often the centerpiece of modern combat fleets. Tactically or even strategically, it replaced the battleship in the role of flagship of a fleet. One of its great advantages is that, by sailing in international waters, it does not interfere with any territorial sovereignty and thus obviates the need for overflight authorizations from third party countries, reduce the times and transit distances of aircraft and therefore significantly increase the time of availability on the combat zone.

thumb|right|upright=1.25|Chart comparing a range of aircraft carriers, from longest (top left) to shortest
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, RN, former First Sea Lord (head) of the Royal Navy, has said, "To put it simply, countries that aspire to strategic international influence have aircraft carriers." Henry Kissinger, while United States Secretary of State, also said: "An aircraft carrier is 100,000 tons of diplomacy".

As of , there are 41 active aircraft carriers in the world operated by thirteen navies. The United States Navy has 11 large nuclear-powered fleet carriers—carrying around 80 fighter jets each—the largest carriers in the world; the total combined deckspace is over twice that of all other nations combined. As well as the aircraft carrier fleet, the U.S. Navy has nine amphibious assault ships used primarily for helicopters, although these also carry up to 20 vertical or short take-off and landing (V/STOL) fighter jets and are similar in size to medium-sized fleet carriers. China, France, India, Russia, and the UK each operate a single large/medium-size carrier, with capacity from 30 to 60 fighter jets. Italy operates two light fleet carriers and Spain operates one. Helicopter carriers are operated by Japan (4), France (3), Australia (2), Egypt (2), Brazil (1), South Korea (1), and Thailand (1). Future aircraft carriers are under construction or in planning by Brazil, China, India, Russia, the United Kingdom, and the United States.

Types of carrier
thumb|Brazilian aircraft carrier , foreground, and U.S. Navy carrier  during a combined training exercise
thumb|, first nuclear-powered carrier of the U.S. 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

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
 Aircraft cruiser
(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.

The Soviet aircraft carrier Admiral Kusnetsov was termed a heavy aircraft-carrying cruiser. This was primarily a legal construct to avoid the limitations of the Montreux Convention preventing 'aircraft carriers' transiting the Turkish Straits between the Soviet Black Sea bases and the Mediterranean. These ships, while sized in the range of large fleet carriers, were designed to deploy alone or with escorts. In addition to supporting fighter aircraft and helicopters, they provide both strong defensive weaponry and heavy offensive missiles equivalent to a guided missile cruiser.

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

Aircraft carriers today are usually divided into the following four categories based on the way that aircraft take off and land:
 Catapult-assisted take-off barrier 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.). All CATOBAR carriers in service today are nuclear powered. Two nations currently operate carriers of this type: ten Nimitz class and one Gerald R. Ford class fleet carriers by the United States, and one medium-sized carrier by France, for a world 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). Today China, India, and Russia each operate one carrier of this type – a total of three in service currently.
 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. The US has nine STOVL amphibious assault ships. The UK has a class of two 65,000 ton STOVL aircraft carriers, HMS Queen Elizabeth and HMS Prince of Wales, the largest warships ever built for the Royal Navy; with one in service and the other being fitted out. Italy operates two in the light fleet role, and Spain operates one amphibious assault ship as a STOVL aircraft carrier, giving a total of thirteen STOVL carriers in active service; (Thailand has one active STOVL carrier but she no longer has any operational STOVL aircraft in inventory so is used and counted as a helicopter carrier).
 Helicopter carrier: Helicopter carriers have a similar appearance to other aircraft carriers but operate only helicopters – those that mainly operate helicopters but can also operate fixed-wing aircraft are known as STOVL carriers (see above). There are currently fourteen helicopter carriers (that solely operate helicopters and not fixed-wing aircraft), operated by seven navies, in commission today. Japan has four of this type, France three, Australia two, Egypt two, and South Korea, Thailand, and Brazil have one each. In the past, some conventional carriers were converted and called commando carriers by the Royal Navy. Some helicopter carriers, but not all, are classified as amphibious assault ships, tasked with landing and supporting ground forces on enemy territory.

By size
thumb|right|The Japanese carrier Shinano was the biggest carrier in World War II, and the largest ship destroyed by a submarine.Enright & Ryan, p. xiv
 Fleet carrier
 Light aircraft carrier
 Escort carrier

Supercarrier

The appellation "supercarrier" is not an official designation with any national navy, but a term used predominantly by the media and typically when reporting on new and upcoming aircraft carrier types. It is also used when comparing carriers of various sizes and capabilities, both current and past. It was first used by The New York Times in 1938, in an article about the Royal Navy's , that had a length of , a displacement of 22,000 tonnes and was designed to carry 72 aircraft. Since then, aircraft carriers have consistently grown in size, both in length and displacement, as well as improved capabilities; in defense, sensors, electronic warfare, propulsion, range, launch and recovery systems, number and types of aircraft carried and number of sorties flown per day.

While the current classes in service, or planned, with the navies of China, India, Russia, and the United Kingdom, with displacements ranging from 65,000 to 85,000 tonnes, lengths ranging from 280 meters (920 ft) to 320 meters (1,050 ft) and varying capabilities, have been described as "supercarriers", the largest "supercarriers" currently in service are with the US Navy, with displacements exceeding 100,000 tonnes, lengths of over 337 meters (1,106 ft), and capabilities that match or exceed that of any other class.

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 Royal Navy and some Commonwealth countries, the hull classification symbols used by the US, 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 CVB  Large aircraft carrier (retired) 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) CVV  Aircraft Carrier (Medium) (proposed) CVL  Light aircraft carrier CVN  Nuclear-powered aircraft carrier CVS  Anti-submarine warfare carrier 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 with the Wright brothers' first flight at Kitty Hawk, North Carolina, 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  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 Royal Navy's pre-dreadnought battleship . 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 Imperial 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 Tondern, Germany (modern day Tønder, Denmark) 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. This resulted in the commissioning of ships such as the Japanese  (1922), followed by  (1924, although laid down before Hōshō in 1918) and  (1927). During World War II, these ships would become known as fleet carriers.

World War II

thumb|right|The Royal Navy's HMS Ark Royal in 1939, with Swordfish biplane bombers passing overhead. The British aircraft carrier was involved in the crippling of the German battleship Bismarck in May 1941
thumb|, the most decorated U.S. warship of World War II

The aircraft carrier dramatically changed naval warfare 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 in the shallow water harbor incapacitated three of the anchored six battleships at a cost of two torpedo bombers.

World War II in the Pacific Ocean involved clashes between aircraft carrier fleets. The Japanese surprise attack on the American Pacific fleet at Pearl Harbor naval / air bases on Sunday, 7 December 1941, 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. Further versatility was demonstrated during the "Doolittle Raid", on 18 April 1942, when US Navy carrier  sailed to within  of Japan and launched 16 B-25 bombers from her deck in a retaliatory strike on the mainland, including the capital, Tokyo. 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 U.S., 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 the hull design was 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 land-based German aircraft.

Postwar era
alt=|thumb|An F6F-5 landing on the French Arromanches in the Tonkin Gulf, 1953.
thumb|USS Tripoli, a U.S. Navy Iwo Jima-class helicopter carrier
thumb|, "The Big E", 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 U.S.N. 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 individual military aircraft over the years. Today's aircraft carriers are so expensive that some nations which operate them risk significant political, economic, social and military impact if a carrier is lost, or is even sent to a potential crisis zone or 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 sailing galleons, frigates and ships-of-the-line and later steam or diesel powered 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, and along with, carrier designs also increased in size and ability. Some of these larger carriers, dubbed by the media as "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 the  and  classes, 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, carrier battle group or carrier strike group.

There is a view among some military pundits that modern anti-ship weapons systems, such as torpedoes and missiles, or even ballistic missiles with nuclear warheads have made aircraft carriers and carrier groups 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.

Description

Structure
thumb|right|STOVL Harriers preparing to take off 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 aircraft carriers 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 fleet carriers 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. 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- or electric-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 of 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|left|F/A-18 Hornet aircraft 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 the optical landing system have provided information on proper glide slope, but LSOs still transmit voice calls to approaching pilots by radio.

thumb| shooter launching F/A-18
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 
alt=|thumb|The command bridge of the aircraft carrier 

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  in 1923. While the island is usually built on the starboard side of the flight 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

The U.S. Navy has the largest carriers in the world, and currently has eleven in service. The UK has two 65,000 tonne STOVL carriers in sea trials. These will enter service in 2020. The navies of China, France, India, and Russia each operate a single medium-sized fleet carrier. The US has nine similarly sized Amphibious Warfare Ships. There are three small light carriers in use capable of operating both fixed-wing aircraft and helicopters, Italy operates two, and Spain one.

Additionally there are fourteen small carriers which only operate helicopters serving the navies of Australia (2), Brazil (1), Egypt (2), France (3), Japan (4), South Korea (1), and Thailand (1).

Australia
Current
thumb|, a 

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

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

Brazil
thumb|, an Ocean-class multi-purpose helicopter carrier, seen in 2010. The ship is now operated by the Brazilian Navy as Atlântico

Current
The Brazilian Navy commissioned the multi-purpose amphibious assault ship and helicopter carrier  on 29 June 2018 in the United Kingdom, which was renamed Atlântico. The helicopter carrier package for Brazil includes an Artisan 3D search radar, KH1007 surface surveillance radar system, four 30 mm DS30M Mk 2 remote weapon systems and four Mk 5B landing craft. However, the three original 20 mm Mk 15 Block 1B Phalanx close-in weapon systems, the torpedo defence systems and 7.62 mm M134 machine guns were removed from the ship before its transfer to Brazil.
The ship displaces 21,578 tonnes, is 203.43 m long and has a range of 8,000 nautical miles. She has been undergoing maintenance work by Babcock and BAE Systems since February.
Scheduled to reach its homeport, Arsenal do Rio de Janeiro (AMRJ), on 25 August, Atlântico will undergo operational sea training under the Royal Navy's Flag Officer Sea Training (FOST) programme.

It was reported in 2017 that Brazil was interested in purchasing Ocean from the UK as a replacement for  which was withdrawn from service in 2017 following multiple mechanical failures. The Royal Navy released an asking price of £80.3 million (US$105,800,871), which the Brazilian Navy called "convenient". In December 2017, the Brazilian Navy confirmed the purchase of Ocean for (GBP) £84.6 million (equivalent to R$359.5M and US$113.2M). The ship was decommissioned from Royal Navy service in March 2018, and after undertaking a period of maintenance in the United Kingdom, is expected to arrive in Rio de Janeiro by the end of 2018 with the intention of being fully operational by 2020.

China
thumb|Liaoning, a Type 001 aircraft carrier

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 she is a training ship, Liaoning is not assigned to any of China's operation fleets.

Future
A second carrier was launched on 26 April 2017. She is the first to be built domestically, to a modified Kuznetsov-class design. The Type 001A aircraft carrier started sea trials on 23 April 2018, and is scheduled to enter service in 2020.

Chinese officials stated that a third carrier, also known as Type 002 carrier is being constructed in the Shanghai Jiangnan Shipyard. She will be the first Chinese aircraft carrier to use catapult take off system. In May 2019, the Centre for Strategic and International Studies released satellite images of what they said was the third carrier under construction at Jiangnan Shipyard near Shanghai.

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 . 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  which also participated in a joint military exercise with the French Navy before arriving at its home port of Alexandria.

Egypt is so far the only country in Africa or the Middle East to possess an aircraft carrier.

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. She 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.

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 40 aircraft. The carrier is being constructed by Cochin Shipyard. The ship was launched in August 2013 and is scheduled for commissioning in 2021.

A second 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 .

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.

Future
Italy plans to replace aging aircraft carrier Garibaldi, as well as one of the San Giorgio-class landing helicopter docks, with a new amphibious assault ship, to be named Trieste. The ship will be significantly larger than her predecessors with a displacement of 33,000 tons at full load. Trieste is to carry the F-35B Joint Strike Fighter.

Japan
thumb|Helicopter carrier Izumo

Current
4 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.
 2  – , 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. Izumos sister ship, Kaga, was commissioned in 2017. In December 2018, the Japanese Cabinet gave approval to convert both ships into aircraft carriers for STOVL operations.

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 she utilizes both systems of launching aircraft. The carrier is expected to cost . Once commissioned, she will replace Admiral Kuznetsov.

South Korea
thumb|, 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
thumb|Spanish Juan Carlos I with Harrier II

Current
: 27,000 tonne, specially designed multipurpose strategic projection ship which can operate as an amphibious assault ship and aircraft carrier. Juan Carlos I has full facilities for both functions including a ski jump for STOVL operations, is equipped with the AV-8B Harrier II attack aircraft. Also, well deck, and vehicle storage area which can be used as additional hangar space, launched in 2008, commissioned 30 September 2010.

Turkey

Future
TCG Anadolu L-408 is a planned amphibious assault ship (LHD) of the Turkish Navy that can be configured as a light aircraft carrier. Construction began on 30 April 2016 by Sedef Shipbuilding Inc. at their Istanbul shipyard and is expected to be completed in 2021.

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. As of 2010, the ship is used for royal transport, helicopter operations, and for disaster relief.

United Kingdom
thumb|, a  of the Royal Navy
Current
One STOVL carrier: the 65,000 tonne  was commissioned in December 2017 with Initial operating capability scheduled for 2020.

Future
The Royal Navy is constructing the second of its larger STOVL  aircraft carriers,  to complete replacement of the three now retired  carriers. Prince of Wales was floated for the first time in late 2017 and is expected to begin sea trials in 2019. Each Queen Elizabeth-class ship is able to operate around 40 aircraft during peacetime operations, up to 50 during wartime, and will have a displacement of 65,000 tonnes.

United States
thumb|Amphibious assault ship 

Current
11 CATOBAR carriers, all nuclear-powered: 
: ten 101,000-ton, 1,092 ft long fleet carriers, 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, 
, one 110,000-ton, 1,106 ft long fleet carrier. The lead of the class , came into service in 2017, with another nine planned.

Nine amphibious assault ships carrying vehicles, Marine fighters, attack and transport helicopters, and landing craft with STOVL fighters for CAS and CAP:
 : 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 11 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.

Future
thumb|, a 

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.

Following the deactivation of  in December 2012, the U.S. fleet comprised 10 fleet carriers, but that number increased back to 11 with the commissioning of Gerald R. Ford in July 2017. The House Armed Services Seapower subcommittee on 24 July 2007, 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 2017) 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.

In a report to Congress in February 2018, the Navy stated it intends to maintain a "12 CVN force" as part of its 30-year acquisition plan.

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.
  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 2022.
  is the subject of a campaign for preservation at Newport, Rhode Island.
  has a preservation campaign to bring her to the West Coast of the United States as the world's first amphibious assault ship museum.

See also

 Airborne aircraft carrier
 Aviation-capable naval vessels
 Carrier-based aircraft
 Lily and Clover
 Merchant aircraft carrier
 Mobile offshore base
 Project Habakkuk
 Seadrome
 Submarine aircraft carrier
 Unsinkable aircraft carrier

Related lists

 List of aircraft carriers
 List of aircraft carriers by configuration
 List of aircraft carriers in service
 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, .
 Chesneau, Roger. Aircraft Carriers of the Word, 1914 to the Present: An Illustrated Encyclopedia. Naval Institute Press, 1984. 
 Francillon, René J, Tonkin Gulf Yacht Club US Carrier Operations off Vietnam, 1988, .
 
 Friedman, Norman. British Carrier Aviation: The Evolution of the Ships and Their Aircraft. Conway Maritime Press, 1988.
 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, .
 
 Polmar, Norman.  Aircraft Carriers: A History of Carrier Aviation and its Influence on World Events, 1901–2006. (two vols.) Potomac Books, 2006. 
 
 Till, Geoffrey. "Adopting the Aircraft Carrier: The British, Japanese, and American Case Studies" in Murray, Williamson; Millet, Allan R, eds. Military Innovation in the Interwar Period. Cambridge University Press, 1996.
 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.

 
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