An aircraft carrier is a warship designed to carry, launch, recover and support aircraft at sea, equipped with a full-length flight deck and hangar facilities that allow it to serve as a mobile, seagoing airbase. Typically it is the capital ship of a fleet (known as a carrier battle group), as it allows a naval force to project seaborne air power far from national territory without depending on local airfields for the staging of aircraft operations. Since their inception in the early 20th century, aircraft carriers have evolved from wooden vessels used to deploy individual tethered reconnaissance balloons, to nuclear-powered supercarriers that carry dozens of fighters, strike aircraft, military helicopters, AEW&Cs and other types of aircraft such as UCAVs. While heavier fixed-wing aircraft such as airlifters, gunships and bombers have been launched from aircraft carriers, these aircraft do not often land on a carrier due to flight deck limitations. The aircraft carrier, along with its onboard aircraft and defensive ancillary weapons, is the largest weapon system ever created. Due to their tactical prowess, mobility, autonomy and the variety of operational means, aircraft carriers are often the centerpiece of modern naval warfare, and have significant diplomatic influence in deterrence, command of the sea and air supremacy. Since the Second World War, the aircraft carrier has replaced the battleship in the role of flagship of a fleet, and largely transformed naval battles from gunfire to beyond-visual-range air strikes. In addition to tactical aptitudes, it has great strategic advantages in that, by sailing in international waters, it does not need to interfere with any territorial sovereignty and thus does not risk diplomatic complications or conflict escalation due to trespassing, and obviates the need for land use authorizations from third-party countries, reduces the times and transit logistics of aircraft and therefore significantly increases the time of availability on the combat zone. Modern navies use several variants of the aircraft carrier which are sometimes categorized as sub-types of aircraft carriers and sometimes as distinct types of 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 August 2026, there are 50 active aircraft carriers in the world operated by fifteen navies. The United States has 11 large nuclear-powered CATOBAR fleet carriers – each carrying around 80 fighters – the largest in the world, with the total combined deck space over twice that of all other nations combined.
Types of carriers
General features Speed is a crucial attribute for aircraft carriers, as they need to be able to be deployed quickly anywhere in the world and have to be fast enough to evade detection and targeting from enemy forces. A high speed also increases the "wind over the deck", boosting the lift available for fixed-wing aircraft to carry fuel and ammunition. To evade nuclear submarines, the carriers should have a speed of more than 30 knots (35 mph; 56 km/h). Aircraft carriers are among the largest types of warships due to their need for ample deck space. An aircraft carrier must be able to perform increasingly diverse mission sets. Diplomacy, power projection, quick crisis response force, land attack from the sea, sea base for helicopter and amphibious assault forces, anti-surface warfare (ASUW), defensive counter air (DCA), and humanitarian aid & disaster relief (HADR) are some of the missions the aircraft carrier is expected to accomplish. Traditionally an aircraft carrier is supposed to be one ship that can perform at least power projection and sea control missions. An aircraft carrier must be able to efficiently operate an air combat group. This means it should handle fixed-wing jets as well as helicopters. This includes ships designed to support operations of short-takeoff/vertical-landing (STOVL) jets.
Basic types Aircraft cruiser Amphibious assault ship and sub-types Anti-submarine warfare carrier Balloon carrier and balloon tenders Escort carrier Fleet carrier Flight deck cruiser Helicopter carrier Light aircraft carrier Seaplane tender and seaplane carriers Utility carrier: This type was mainly used in the US Navy, in the decade after World War 2 to ferry aircraft. 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 Sea. 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
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 except the Fujian. Thirteen are in service: ten Nimitz class and one Gerald R. Ford-class carrier in the United States, Fujian in China, and Charles de Gaulle in France. Short take-off barrier-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 Admiral Kuznetsov 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). Five are in service: two in China, two in India, and one in Russia. Short take-off vertical-landing (STOVL): limited to carrying STOVL aircraft. STOVL aircraft, such as the Harrier 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 Lockheed Martin F-35B Lightning II, has much improved performance. Fourteen are in service; nine STOVL amphibious assault ships in the US; the UK has two Queen Elizabeth Class carriers, and Italy has one carrier and one amphibious assault ship, with one STOVL amphibious assault ship in Spain. Helicopter carrier: These 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). Seventeen are in service: four in Japan; three in France; two each in Australia, China, Egypt and South Korea; and one each in Brazil and Thailand. In the past, some conventional carriers were converted and these were 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 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 larger and more advanced 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 HMS Ark Royal, that had a length of 800 feet (244 m), a displacement of 22,000 tons 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. The first aircraft carrier over 80,000 tonnes full-load displacement was the USS Forrestal launched in 1954. In total, the US Navy has had 5 different classes of aircraft carrier of this size definition, the Forrestal class, Kitty Hawk class, the Enterprise class, the Nimitz class and Gerald R Ford Class, two of which were conventional steam-powered and three nuclear-powered. USS Enterprise, launched in 1960, was the first carrier over 90,000 tonnes full load displacement and Nimitz, launched in 1972, was the first over 100,000 tonnes displacement. A total of 22 supercarriers have been launched by the US Navy since 1954, with 11 currently in service. Both China (Type 003) and the United Kingdom (Queen Elizabeth class) have carriers in service with displacements from 80,000 to 85,000 tonnes and lengths from 280 to 320 meters (920 to 1,050 ft) which are described as "supercarriers". France is also developing a new aircraft carrier (PANG) which is to have a full load displacement of 80,000 tonnes and will be considered a supercarrier. The largest supercarrier in service as of 2024 is the US Navy's USS Gerald R. Ford, with full load displacement of around 100,000 tons, length of 337 meters (1,106 ft) and capabilities that exceed those of any other class.
Ultracarrier A US Navy proposal for an aircraft carrier concept with a length of 1,310 feet and a displacement of 500,000 tons full load at a cost of $828 million in 1976 dollars. Project Habakkuk could be considered an early proposal for an "ultracarrier".
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, Commonwealth countries, and Europe, along with the hull classification symbols used by the US and Canada.
History
Origins
The 1903 advent of the heavier-than-air fixed-wing airplane with the Wright brothers' first flight at Kitty Hawk, North Carolina, was 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 USS Birmingham 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 take off of an airplane from a ship while underway was made by Commander Charles Samson flying a Short Improved S.27 biplane "S.38" of the Royal Naval Air Service (RNAS) from the deck of the Royal Navy's pre-dreadnought battleship HMS Hibernia, thus providing the first practical demonstration of the aircraft carrier for naval operations at sea. Seaplane tender support ships came next, with the French Foudre of 1911. Early in World War I, the Imperial Japanese Navy ship Wakamiya conducted the world's first carrier-launched air raid: on 6 September 1914, the Wakamiya used its crane to lower Farman seaplanes into the water. The Wakamiya attacked the Austro-Hungarian cruiser SMS Kaiserin Elisabeth and the Imperial German gunboat Jaguar in Jiaozhou Bay off Qingdao; neither was hit. The first attack using an air-launched torpedo occurred on 2 August, when a torpedo was fired by Flight Commander Charles Edmonds from a Short Type 184 seaplane, launched from the seaplane carrier HMS Ben-my-Chree. The first carrier-launched airstrike was the Tondern raid in July 1918. Seven Sopwith Camels were launched from the battlecruiser HMS Furious, which had been completed as a carrier by replacing her planned forward turret with a flight deck and hangar prior to commissioning. The Camels attacked and damaged the German airbase at Tondern, Germany (modern day Tønder, Denmark), and destroyed two zeppelin airships. The first landing of an airplane on a moving ship was by Squadron Commander Edwin Harris Dunning, when he landed his Sopwith Pup on HMS Furious in Scapa Flow, Orkney, on 2 August 1917. Landing on the forward flight deck required the pilot to approach round the ship's superstructure, a difficult and dangerous manoeuver, and Dunning was later killed when his airplane was thrown overboard while attempting another landing on Furious. HMS Furious was modified again when her rear turret was removed and another flight deck added over a second hangar for landing aircraft over the stern. Her funnel and superstructure remained intact, however, and turbulence from the funnel and superstructure was severe enough that only three landing attempts were successful before further attempts were forbidden. This experience prompted the development of vessels with a flush deck and produced the first large fleet ships. In 1918, HMS Argus 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 USS Langley in 1922, the US Lexington-class aircraft carriers (1927), Japanese Akagi and Kaga, and British Courageous class (of which Furious was one). 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 Hōshō (1922), HMS Hermes (1924, although laid down in 1918 before Hōshō), and Béarn (1927). During World War II, these ships would become known as fleet carriers.
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 HMS Illustrious 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 six anchored 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 and 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. In the "Doolittle Raid", on 18 April 1942, the US Navy carrier USS Hornet sailed to within 650 nautical miles (1,200 km) of Japan and launched 16 B-25 Mitchell medium bombers from her deck in a demonstrative retaliatory strike on the mainland, including the capital, Tokyo. However, the vulnerability of carriers compared to traditional capital ships was illustrated by the sinking of HMS Glorious by German battleships during the Norwegian campaign in 1940. This new-found importance of naval aviation prompted nations to create a number of carriers, in efforts to provide air superiority cover for every major fleet to ward off enemy aircraft. This extensive usage led to the development and construction of 'light' carriers. Escort aircraft carriers, such as USS Bogue, 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 USS Independence (commissioned in 1943), 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. Noteworthy converted carriers were also USS Sable (IX-81) and USS Wolverine (IX-64) that both operated on the Great Lakes for training duties and were converted from paddle steamers, making them the only aircraft carriers with this type of propulsion.
Postwar era
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 Nimitz class of US Navy carriers has a displacement nearly four times that of the World War II–era USS Enterprise, 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 economic and military impact if a carrier is lost.
Some changes were made after 1945 in carriers:
The angled flight deck was invented by Royal Navy Captain (later Rear Admiral) Dennis Cambell, as naval aviation jets' higher speeds required carriers be modified to fit their needs. Additionally, the angled flight deck allows for simultaneous launch and recovery. Jet blast deflectors became necessary to protect aircraft and handlers from jet blast. The first US Navy carriers to be fitted with them were the wooden-decked Essex-class aircraft carriers which were adapted to operate jets in the late 1940s. Later versions had to be water-cooled because of increasing engine power. Optical landing systems were developed to facilitate the very precise landing angles required by jet aircraft, which have a faster landing speed giving the pilot little time to correct misalignments, or mistakes. The first system was fitted to HMS Illustrious in 1952. Aircraft carrier designs have increased in size to accommodate continuous increase in aircraft size. The 1950s saw US Navy's commission of "supercarriers", designed to operate naval jets, which offered better performance at the expense of bigger size and demanded more ordnance to be carried on-board (fuel, spare parts, electronics, etc.). The combination of increased carrier size, speed requirements above 30 knots (35 mph; 56 km/h), and a requirement to operate at sea for long periods mean that modern large aircraft carriers often use nuclear reactors to create power for propulsion, electricity, catapulting airplanes from aircraft carriers, and a few more minor uses. Modern navies that operate such aircraft carriers treat them as capital ships of fleets, a role previously held by the galleons, ships-of-the-line and battleships. 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 tons 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 Wasp and Mistral classes, serve the purpose of carrying and landing Marines, and operate a large contingent of helicopters for that purpose. Also known as "commando carriers" or "helicopter carriers", many have the capability to operate VSTOL aircraft. The threatening role of aircraft carriers has a place in modern asymmetric warfare, like the gunboat diplomacy of the past. Carriers also facilitate quick and precise projections of overwhelming military power into such local and regional conflicts. 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, re-supply (Many carriers are self-sufficient and will supply their escorts) and perform other support services, and to provide additional offensive capabilities. The resulting group of ships is often termed a carrier strike group, battle group, carrier group, or carrier battle 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 too vulnerable for modern combat. Carriers can also be vulnerable to diesel-electric submarines like the German U24 of the conventional 206 class which in 2001 "fired" at Enterprise during the exercise JTFEX 01-2 in the Caribbean Sea by firing flares and taking a photograph through its periscope or the Swedish Navy submarine Gotland, which managed the same feat in 2006 during JTFEX 06-2 by penetrating the defensive measures of Carrier Strike Group 7 which was protecting USS Ronald Reagan.
Description
Structure
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 and French aircraft carriers are notable for having nuclear reactors powering their systems and propulsion. 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 ship navigation from the bridge and air traffic control from flyco are controlled and (in non-nuclear powered vessels), provides the location of the ship's funnel(s). The Queen Elizabeth-class has two island structures; the forward island contains the navigation bridge, while the aft structure houses flyco. The constraints of constructing a flight deck strongly affect the role of a given carrier, 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 US Navy fleet carriers as it allows the deployment of heavy jets with full load-outs, 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. 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. Munitions are commonly stored on the lower decks because they are highly explosive. Usually this is below the waterline so that the area can be flooded in case of emergency.
Flight deck
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. Creating such a surface at sea poses constraints on the carrier. For example, the size of the vessel is a fundamental limitation on runway length. 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 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 Barrier 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 Barrier 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 BAe 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 Lockheed F-35B Lightning II, which demonstrated VTOL capability in test flights but is operationally STOVL or in the case of UK uses "shipborne rolling vertical landing". Vertical Take-Off and Landing (VTOL): Certain 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 due to the additional weight from associated systems. On the recovery side of the flight deck, the adaptation to the aircraft load-out 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-World War II 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
Carriers steam at speed, up to 35 knots (65 km/h; 40 mph) 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. 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 US 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
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 HMS Hermes in 1923. While the island is usually built on the starboard side of the flight deck, the Japanese aircraft carriers Akagi and Hiryū 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 USS Langley. 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 short take off vertical landing (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 downward. 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. 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 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 cannot 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 Sukhoi Su-33 is only able to launch from the carrier Admiral Kuznetsov with a minimal armament and fuel load. Another disadvantage is on mixed flight deck operations where helicopters are also present, such as on 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 United States operates 11 nuclear-powered, catapult-assisted carriers, with a total combined deck space over twice that of all other nations combined as of 2016. China operates one catapult-assisted aircraft carrier and two ski-jump carriers. The United Kingdom and India each currently operate two ski-jump aircraft carriers, and France operates one nuclear-powered, catapult-assisted carrier. Russia deploys one ski-jump carrier, although it has not been operational since 2017. In addition, the US operates nine large amphibious assault ships with the capability to launch vertical/short takeoff and landing (V/STOL) aircraft, and China operates four amphibious assault ships of a similar size as helicopter carriers. Italy operates two light V/STOL carriers, and both Spain and Iran operate one V/STOL aircraft-carrying assault ship. Helicopter carriers are also operated by Japan (4, two converting to operate V/STOL fighters) France (3), Australia (2), Egypt (2), South Korea (2), Thailand (1), Brazil (1) and Iran (1). Future aircraft carriers are under construction or planned by China, France, India, Italy, Russia, South Korea, and the US.
Algeria Current Kalaat Béni Abbès (L-474) is an amphibious transport dock of the Algerian National Navy with two deck-landing spots for helicopters.
Australia
Current The Royal Australian Navy operates two Canberra-class landing helicopter docks. The two-ship class, based on the Spanish vessel Juan Carlos I and built by Navantia and BAE Systems Australia, represents the largest ships ever built for the Royal Australian Navy. HMAS Canberra underwent sea trials in late 2013 and was commissioned in 2014. Her sister ship, HMAS Adelaide, 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 Current In December 2017, the Brazilian Navy confirmed the purchase of HMS Ocean for (GBP) £84.6 million (equivalent to R$359.5M and US$113.2M) and renamed her Atlântico. The ship was decommissioned from Royal Navy service in March 2018. The Brazilian Navy commissioned the carrier on 29 June 2018 in the United Kingdom. After undertaking a period of maintenance in the UK, the ship travelled to its new home port, Rio de Janeiro Navy Arsenal (AMRJ) to be fully operational by 2020. The ship displaces 21,578 tonnes, is 203.43 meters (667.4 ft) long and has a range of 8,000 nautical miles (15,000 km; 9,200 mi). Before leaving HMNB Devonport for her new homeport in Rio's AMRJ, Atlântico underwent operational sea training under the Royal Navy's Flag Officer Sea Training (FOST) program. On 12 November 2020, Atlântico was redesignated "NAM", for "multipurpose aircraft carrier" (Portuguese: Navio Aeródromo Multipropósito), from "PHM", for "multipurpose helicopter carrier" (Portuguese: Porta-Helicópteros Multipropósito), to reflect the ship's capability to operate with fixed-wing medium-altitude long-endurance unmanned aerial vehicles as well as crewed tiltrotor VTOL aircraft.
China
Current Two STOBAR carriers:
Liaoning (60,900 tons) was originally built as the uncompleted Soviet Kuznetsov-class carrier Varyag and was later purchased as a hulk from Ukraine in 1998 on the pretext of commercial use as a floating casino, then towed to China for rebuild and completion. Liaoning was commissioned on 25 September 2012 and began service for testing and training. In November 2012, Liaoning launched and recovered Shenyang J-15 naval fighter aircraft for the first time. After a refit in January 2019, she was assigned to the North Sea Fleet, a change from her previous role as a training ship. Shandong (60,000–70,000 tons) was launched on 26 April 2017, the first to be built domestically based on an improved