An aircraft carrier is a warship designed to deploy and recover aircraft — in effect acting as a sea-going airbase. Aircraft carriers thus allow a naval force to project air power great distances without having to depend on local bases for land-based aircraft.

Modern navies that operate such ships treat aircraft carriers as the capital ship of the fleet, a role previously played by the battleship. The change, part of the growth of air power as a significant part of warfare, took place during World War II. A battleship could hurl hundreds of large caliber shells at a target and score possibly a dozen hits. Their maximum range was usually no more than thirty miles. However, aircraft launched from a carrier could deliver devastating aerial assaults by the beginning of World War II up to two hundred miles away. The advent of "smart weapons" have further increased the lethality of aircrafts to ranges of over one hundred miles. Thus, the aircraft carrier could perform the original mission of the battleship, causing heavy damage to an enemy fleet at great distance and with superior accuracy. Due to the long range of the striking aircraft heavy armour was less of a requirement and because of this, for example during World War II, aircraft carriers were less expensive and time consuming to build than battleships. Unescorted carriers are considered vulnerable to attack by other ships, aircraft, submarines or missiles and therefore travel as part of a carrier battle group. Unlike other types of capital ships in the 20th century, aircraft carrier designs since World War II have been effectively unlimited by any consideration save budgetary, and the ships have increased in size to handle the larger aircraft: The large, modern Nimitz class of United States 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.

 

Main article: Flight deck

The key aspect of the aircraft carrier is that it is, in effect, a runway at sea and modern aircraft carriers have a flat-top deck design that serves as a flight deck for take-off and landing of aircraft. Aircraft take off to the front, into the wind, and land from the rear. Carriers steam at speed, for example up to 35 knots (65 km/h), into the wind during take-off in order to increase the apparent wind speed, thereby reducing the speed of the aircraft relative to the ship. On some ships, a steam-powered catapult is used to propel the aircraft forward assisting the power of its engines and allowing it to take off in a shorter distance than would otherwise be required, even with the headwind effect of the ship's course. On other carriers, aircraft do not require assistance for take off — the requirement for assistance relates to aircraft design and performance. Conversely, when landing on a carrier, conventional aircraft rely upon a tailhook that catches on arrestor wires stretched across the deck to bring them to a stop in a shorter distance than normal. Other aircraft — helicopters and V/STOL (Vertical/Short Take-Off and Landing) designs — utilize their hover capability to land vertically and so require no assistance in speed reduction upon landing.

Conventional ("tailhook") aircraft rely upon a landing signal officer (LSO) to control the plane's landing approach, visually gauging altitude, attitude, and speed, and transmitting that data to the pilot. Before the angled deck emerged in the 1950s, LSOs used colored paddles to signal corrections to the pilot. From the late 1950s onward, visual landing aids such as mirrors provided information on proper glide slope, but LSOs still transmit voice calls to landing pilots by radio.

Since the early 1950s it has been common to direct the landing recovery area off to port at an angle to the line of the ship. The primary function of the angled deck landing area is to allow aircraft who miss the arresting wires, referred to as a "bolter", to become airborne again without the risk of hitting aircraft parked on the forward parts of the deck. The angled deck also allows launching of aircraft at the same time as others land.

The above deck areas of the warship (the bridge, flight control tower, and so on) are concentrated to the starboard side of the deck in a relatively small area called an "island". Very few carriers have been designed or built without an island and such a configuration has not been seen in a fleet sized carrier.

A more recent configuration, used by the British Royal Navy, has a 'ski-jump' ramp at the forward end of the flight deck. This was developed to help launch VTOL (or STOVL) aircraft (aircraft that are able to take off and land with little or no forward movement) such as the Sea Harrier. Although the aircraft are capable of flying vertically off the deck, using the ramp is more fuel efficient. As catapults and arrestor cables are unnecessary, carriers with this arrangement reduce weight, complexity, and space needed for equipment. The disadvantage of the ski jump — and hence, the reason this configuration has not appeared on American supercarriers — is the penalty that it exacts on aircraft size, payload and fuel load (and hence, range): Large, slow planes like the E-2 Hawkeye and heavily-laden strike fighters like the F/A-18E/F Super Hornet cannot use a ski jump because their high weight requires either a longer takeoff roll than is possible on a carrier deck (even on the large Russian aircraft carrier Kuznetsov, lightly-loaded Su-33 air superiority fighters require almost the entire length of the deck to take off) or catapult assistance.

Over the course of the last century there have been several types of aircraft carrier, some of which are now obsolete. They can be generally categorized as follows:

• Balloon carriers were used during in the 19th and early 20th century, mainly for observation purposes.
• Seaplane tenders, such as HMS Engadine, and USS Avocet AVP-4 continued to be used through World War 2. Though seaplanes are inferior to conventional aircraft in the role of a fighter, they are very valuable for patrol and rescue missions among others. The USN actually converted it's first aircraft carrier, USS Langley CV-1, to a seaplane tender designated AV-3 in 1937 and continued in this role until sunk early in the war.
• Standard carriers, such as HMS Ark Royal, typically 20,000 to 65,000 tonnes. Often known as "fleet carriers"
• Flying aircraft carrier; an airship that can carry aircraft. Examples include USS Akron and Macon
• Escort aircraft carriers, such as USS Barnes, were built only during World War II, and were used by the British Royal Navy and U.S. Navy
• Light aircraft carriers, such as USS Independence, were designed to primarily carry fighters
• CAM ships, such as SS Michael E, cargo carrying merchant ships which could launch but not retrieve fighter aircraft. These vessels were an emergency measure during World War II
• Merchant aircraft carriers (MACs), such as MV Empire MacAlpine, another emergency measure which saw cargo-carrying merchant ships equipped with flight decks
• Battlecarriers were created by the Imperial Japanese Navy to partially compensate for the loss of carrier strength at Midway. Two of them were made from Ise class battleships during late 1943. The aft turrets were removed and replaced with a hangar, deck and catapult. The heavy cruiser Mogami concurrently received a similar conversion. With half a flight deck and half of a battleship's armament, the ships were singularly worthless and seldom left port.
• Submarine aircraft carriers, such as the French Surcouf, or the Japanese I-400 class submarines which were capable of carrying 3 Aichi M6A Seiran aircraft. The first of these were built in the 1920s

Some cruisers and capital ships of the inter-war years often carried a catapult launched seaplane for reconnaissance and spotting the fall of the guns. It was launched by a catapult and recovered by crane from the water after landing. These were highly successful during World War II; there were many notable successes early in the war as shown by HMS Warspite’s float equipped Swordfish during operations in the Norwegian fjords in 1940. The Japanese Rufe floatplane derived from the Zero was a formidable fighter with only a slight loss in flight performance, one of their pilots scored 26 kills in the A6M2-N Rufe; a score only bettered by a handful of American pilots throughout WW2. Other Japanese seaplanes launched from tenders and warships sank merchant ships and small-scale ground attacks. The culmination of the type was the American 300+ mph Curtiss SC Seahawk which was actually a fighter aircraft like the Rufe in addition to a two-seat gunnery spotter and transport for an injured man in a litter. Spotter seaplane aircraft on U.S. Navy cruisers and battleships were in service until 1949. Seaplane fighters were considered poor combat aircraft compared to their carrier-launched brethren; they were slower due to the drag of their pontoons or boat hulls. Contemporary propellor-driven, landplane fighter aircraft were much faster (450-480 mph as opposed to 300-350) and more heavily armed. The Curtiss Seahawk only had two .50 calibre machine guns compared to four 20mm cannon in the Grumman F8F Bearcat or four .50 cal machine guns plus two 20mm cannon in the Vought F4U Corsair. Jet aircraft of just a few years later were faster still (500+ mph) and still better armed, especially with the development of air to air missiles in the early to mid 1950s.

• Amphibious assault carriers, such as USS Tarawa, which often also 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".
• Anti-submarine warfare carriers, also known as "helicopter carriers."
• Supercarriers, such as USS Nimitz, typically 75,000 tonnes or greater. Many are powered by nuclear reactors and form the core of a fleet designed to operate far from home. As of 12/21/2006 the USS Kitty Hawk CV-63 and the USS John F. Kennedy CV-67 are the only conventional (non-nuclear) supercarriers in service.

Many modern warships have helicopter landing capability and helicopter assault ships represent a new form of amphibious assault carrier.

In the immediate post war era there was interest in jet propelled seaplanes which would avoid the limitations imposed by jet aircraft on aircraft carriers. The most advanced of these were the flying-boat jet fighters; the US F2Y Sea Dart (1953) and UK Saunders-Roe SR.A/1 (1947). In the event carrier design caught up quickly and military seaplanes passed largley into history though not before the F2Y set the record for being the only flying boat ever to travel faster than sound.

Though aircraft carriers are given their definition with respect to fixed-wing aircraft, the first known instance of using a ship for airborne operations occurred in 1806, when the British Royal Navy's Lord Thomas Cochrane launched kites from the 32-gun frigate HMS Pallas in order to drop propaganda leaflets on the French territory.

Main article: Balloon carrier

On July 12, 1849, the Austrian Navy ship Vulcano launched a manned hot air balloon in order to drop bombs on Venice, although the attempt failed due to contrary winds.

Later, during the American Civil War, about the time of the Peninsula Campaign, gas-filled balloons were being used to perform reconnaissance on Confederate positions, the battles turned inland into the heavily forested areas of the Peninsula where balloons could not travel. A coal barge, the George Washington Parke Custis, was cleared of all deck rigging to accommodate the gas generators and apparatus of balloons. From the GWP Prof. Thaddeus S. C. Lowe, Chief Aeronaut of the Union Army Balloon Corps, made his first ascents over the Potomac River and telegraphed claims of the success of the first aerial venture ever made from a water-borne vessel. Other barges were converted to assist with the other military balloons transported about the eastern waterways. It is only fair to point out in deference to modern aircraft carriers that none of these Civil War crafts had ever taken to the high seas.

Balloons launched from ships led to the development of balloon carriers, or balloon tenders, during World War I, by the navies of Great Britain, France, Germany, Italy, Russia, and Sweden. About ten such "balloon tenders" were built, their main objective being aerial observation posts. These ships were either decommissioned or converted to seaplane tenders after the war.

Main article: Seaplane carrier

The invention of the seaplane in March 1910 with the French Le Canard led to the earliest development of a ship designed to carry airplanes, albeit equipped with floats: in December 1911 appears the French Navy La Foudre, the first seaplane carrier, and the first known carrier of airplanes. Commissioned as a seaplane tender, and carrying float-equipped planes under hangars on the main deck, from where they were lowered on the sea with a crane, she participated in tactical exercises in the Mediterranean in 1912. La Foudre was further modified in November 1913 with a 10 meters flat deck to launch her seaplanes.

HMS Hermes, temporarily converted as an experimental seaplane carrier in April-May 1913, is also one of the first seaplane carriers, and the first experimental seaplane carrier of the British Navy. She was originally laid down as a merchant ship, but was converted on the building stocks to be a seaplane carrier for a few trials in 1913, before being converted again to a cruiser, and back again to a seaplane carrier in 1914. She was sunk by a German submarine in October 1914. The first seaplane tender of the US Navy was the USS Mississippi, converted to that role in December 1913.

"An airplane-carrying vessel is indispensable. These vessels will be constructed on a plan very different from what is currently used. First of all the deck will be cleared of all obstacles. It will be flat, as wide as possible without jeopardizing the nautical lines of the hull, and it will look like a landing field."

Clément Ader, "L'Aviation Militaire", 1909

As heavier-than-air aircraft developed in the early 20th century various navies began to take an interest in their potential use as scouts for their big gun warships. In 1909 the French inventor Clément Ader published in his book "L'Aviation Militaire" the description of a ship to operate airplanes at sea, with a flat flight deck, an island superstructure, deck elevators and a hangar bay. That year the US Naval Attaché in Paris sent a report on his observations.

A number of experimental flights were made to test the concept. Eugene Ely was the first pilot to launch from a stationary ship in November 1910. He took off from a structure fixed over the forecastle of the US armored cruiser USS Birmingham at Hampton Roads, Virginia and landed nearby on Willoughby Spit after some five minutes in the air.

On January 18, 1911 he became the first pilot to land on a stationary ship. He took off from the Tanforan racetrack and landed on a similar temporary structure on the aft of USS Pennsylvania anchored at the San Francisco waterfront — the improvised braking system of sandbags and ropes led directly to the arrestor hook and wires described above. His aircraft was then turned around and he was able to take off again. Commander Charles Samson, RN, became the first airman to take off from a moving warship on May 2, 1912. He took off in a Short S27 from the battleship HMS Hibernia while she steamed at 10.5 knots (19 km/h) during the Royal Fleet Review at Weymouth.

HMS Ark Royal was arguably the first modern aircraft carrier. She was originally laid down as a merchant ship, but was converted on the building stocks to be a hybrid airplane/ seaplane carrier. Launched in 1914, she served in the Dardanelles campaign and throughout World War I.

The first strike from a carrier against a land target took place on July 19, 1918. Seven Sopwith Camels launched from HMS Furious attacked the German Zeppelin base at Tondern, with two 50 lb bombs each. Several airships and balloons were destroyed, but as the carrier had no method of recovering the aircraft safely, two of the pilots ditched their aircraft in the sea alongside the carrier while the others headed for neutral Denmark.

The Washington Naval Treaty of 1922 placed strict limits on the tonnages of battleships and battlecruisers for the major naval powers after World War I, as well as limits not only on the total tonnage for carriers, but also an upper limit on 27,000 tonnes for each ship. Although exceptions were made regarding the max ship tonnage (fleet units counted, experimental units did not), the total tonnage could not be exceeded. However, while all of the major navies were over-tonnage on battleships, they were all considerably under-tonnage on aircraft carriers. Consequently, many battleships and battlecruisers under construction (or in service) were converted into aircraft carriers. The first ship to have a full length flat deck was HMS Argus the conversion of which was completed in September 1918, with the U.S. Navy not following suit until 1920, when the conversion of USS Langley (an experimental ship which did not count against America's carrier tonnage) had completed. The first American fleet carriers would not join the service until 1928 (USS Lexington and Saratoga).

The first purpose-designed aircraft carrier to be developed was the HMS Hermes, although the first one to be commissioned was the Japanese Hōshō (commissioned in December 1922, followed by HMS Hermes in July 1923). Hermes' design preceded and influenced that of Hōshō, and its construction actually began earlier, but numerous tests, experiments and budget considerations delayed its commission.

By the late 1930s, aircraft carriers around the world typically carried three types of aircraft: torpedo bombers, also used for conventional bombings and reconnaissance; dive bombers, also used for reconnaissance (in the U.S. Navy, this type of aircraft were known as "scout bombers"); and fighters for fleet defence and bomber escort duties. Because of the restricted space on aircraft carriers, all these aircraft were of small, single-engined types, usually with folding wings to facilitate storage.

Aircraft carriers played a significant role in World War II. With seven aircraft carriers afloat, the British Royal Navy had a considerable numerical advantage at the start of the war as neither the Germans nor the Italians had carriers of their own. However, the vulnerability of carriers compared to traditional battleships when forced into a gun-range encounter was quickly illustrated by the sinking of HMS Glorious by German battlecruisers during the Norwegian campaign in 1940.

This apparent weakness to battleships was turned on its head in November 1940 when HMS Illustrious launched a long-range strike on the Italian fleet at Taranto. This operation incapacitated three of the six battleships in the harbour at a cost of two of the 21 attacking Fairey Swordfish torpedo bombers. Carriers also played a major part in reinforcing Malta, both by transporting planes and by defending convoys sent to supply the besieged island. The use of carriers prevented the Italian Navy and land-based German aircraft from dominating the Mediterranean theatre.

In the Atlantic, aircraft from HMS Ark Royal and HMS Victorious were responsible for slowing Bismarck during May 1941. Later in the war, escort carriers proved their worth guarding convoys crossing the Atlantic and Arctic oceans.

Many of the major battles in the Pacific involved aircraft carriers. Japan started the war with ten aircraft carriers, the largest and most modern carrier fleet in the world at that time. There were six American aircraft carriers at the beginning of the hostilities, although only three of them were operating in the Pacific.

Drawing on the 1939 Japanese development of shallow water modifications for aerial torpedoes and the 1940 British aerial attack on the Italian fleet at Taranto, the 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 flattops in a single striking unit marked a turning point in naval history, as no other nation had fielded anything comparable. (Though Germany and Italy began construction of carriers, neither were completed. Of the two, Germany's Graf Zeppelin had the greater potential.)

Meanwhile, the Japanese began their advance through Southeast Asia and the sinking of Prince of Wales and Repulse by Japanese land-based aircraft drove home the need for this ship class for fleet defence from aerial attack. In April 1942, the Japanese fast carrier strike force ranged into the Indian Ocean and sank shipping, including the damaged and undefended carrier HMS Hermes. Smaller Allied fleets with inadequate aerial protection were forced to retreat or be destroyed. In the Coral Sea, US and Japanese fleets traded aircraft strikes in the first battle where neither side's ships sighted the other. At the Battle of Midway all four Japanese carriers engaged were sunk by planes from three American carriers (one of which was lost) and the battle is considered the turning point of the war in the Pacific. Notably, the battle was orchestrated by the Japanese to draw out American carriers that had proven very elusive and troublesome to the Japanese.

Subsequently the US was able to build up large numbers of aircraft aboard a mixture of fleet, light and (newly commissioned) escort carriers, primarily with the introduction of the Essex class in 1943. These ships, around which were built the fast carrier task forces of the Third and Fifth Fleets, played a major part in winning the Pacific war. The eclipse of the battleship as the primary component of a fleet was clearly illustrated by the sinking of the largest battleship ever built, Yamato, by carrier-borne aircraft in 1945. Japan also built the largest aircraft carrier of the war, Shinano, which was a Yamato class ship converted mid-way through construction after the disasterous loss of four fleet carriers at Midway. She was sunk by a patrolling US submarine while in transit shortly after commissioning, but before being fully outfiotted or operational in November 1944.

Combat experience proved that the British invention of the sealed "hurricane bow" which protected against storms was superior to any other use for the very front of the ship, be it machine-guns or a second flight deck. This became standard for British and American carriers. The Japanese carrier Taihō was the first of their ships to incorporate it.

Starting late in the war with the Midway class, American carriers had grown so large that it was no longer practical to continue the concept of designing the hangar deck to be the strength deck, and all subsequent American carriers have the flight deck as the strength deck, leaving only the island as superstructure.

The loss of three major carriers in quick succession in the Pacific led the US Navy to develop the light carrier (CVL) from light cruiser hulls that had already been laid down. These were intended to add fighter squadrons to a task force, and were used in the US Navy only during World War II. The actual U.S. Navy classification was small aircraft carrier (CVL), not light. Prior to July 1943, they were just classified as aircraft carriers (CV).

The British Royal Navy made a similar design which served both them and Commonwealth countries after World War II. One of these carriers, India's INS Viraat, formerly HMS Hermes, is still being used.

To protect Atlantic convoys, the British developed what they called Merchant Aircraft Carriers, which were merchant ships equipped with a flat deck for half a dozen aircraft. These operated with civilian crews, under merchant colors, and carried their normal cargo besides providing air support for the convoy. As there was no lift or hangar, aircraft maintenance was limited and the aircraft spent the entire trip sitting on the deck.

These served as stop-gap until dedicated escort carriers could be built in the US (US classification CVE). About a third of the size of a fleet carrier, it carried about two dozen aircraft for anti-submarine duties. Over one hundred were built or converted from merchantmen.

Escort carriers were built in the US from two basic hull designs: one from a merchant ship, and the other from a slightly larger, slightly faster tanker. Besides defending convoys, these were used to transport aircraft across the ocean. Nevertheless, some participated in the battles to liberate the Philippines, notably the battle off Samar in which six escort carriers and their escorting destroyers briefly took on five Japanese battleships and bluffed them into retreating.

As an emergency stop-gap before sufficient merchant aircraft carriers became available, the British provided air cover for convoys using Catapult aircraft merchantman (CAM ships) and merchant aircraft carriers. CAM ships were merchant vessels equipped with an aircraft, usually a battle-weary Hawker Hurricane, launched by a catapult. Once launched, the aircraft could not land back on the deck and had to ditch in the sea if it was not within range of land. Over two years, fewer than 10 launches were ever made, yet these flights did have some success: 6 bombers for the loss of a single pilot.

Three major post-war developments came from the need to improve operations of jet-powered aircraft, which had higher weights and landing speeds than their propeller-powered forebearers.

During the Second World War, aircraft would land on the flight deck parallel to the long axis of the ship's hull. Aircraft which had already landed would be parked on the deck at the bow end of the flight deck. A crash barrier was raised behind them to stop any landing aircraft which overshot the landing area because its landing hook missed the arrestor cables. If this happened, it would often cause serious damage or injury and even, if the crash barrier was not strong enough, destruction of parked aircraft.

An important development of the early 1950s was the British invention of the angled deck, where the runway was canted at an angle of a few degrees across the ship. If an aircraft misses the arrestor cables, the pilot only needs to increase engine power to maximum to get airborne again and will not hit the parked aircraft because the angled deck points out over the sea. The USS John C. Stennis is an example of an aircraft carrier that utilizes the concept of an angled landing deck.

The modern steam-powered catapult, powered by steam from the ship's boilers or reactors, was invented by Commander C.C. Mitchell RNVR. It was widely adopted following trials on HMS Perseus between 1950 and 1952 which showed it to be more powerful and reliable than the compressed air catapults which had been introduced in the 1930s.

Another British invention was the glideslope indicator (also known as a "meatball"). This was a gyroscopically-controlled lamp (which used a Fresnel lens) on the port side of the deck which could be seen by the aviator who was about to land, indicating to him whether he was too high or too low in relation to the desired glidepath. It also took into account the effect of the waves on the flight deck. The device became a necessity as the landing speed of aircraft increased.

The US Navy prematurely attempted to become a strategic nuclear force with the project to build United States, termed CVA, with the "A" signifying "atomic". This ship would have carried twin-propeller bombers, each of which could carry an atomic bomb. The project was cancelled under pressure from the newly-created United States Air Force, and the letter "A" was re-cycled to mean "attack." But this only delayed the growth of carriers. Nuclear weapons would put to sea despite Air Force objections in 1955 aboard USS Forrestal, and by the end of the fifties the Navy had a series of nuclear-armed attack aircraft.

The US Navy also built aircraft carriers powered by nuclear reactors. USS Enterprise was the first aircraft carrier and second warship (after USS Long Beach) to be powered in this way and subsequent supercarriers took advantage of this technology to increase their endurance. The only other nation to have followed the US lead is France with Charles de Gaulle.

The post-war years also saw the development of the helicopter with different capabilities to a fighter aircraft. Whereas fixed-wing aircraft are suited to air-to-air combat and air-to-surface attack, helicopters are used to transport equipment and personnel and can be used in an anti-submarine warfare role with dipped sonar and missiles.

In the late 1950s and early 1960s, the UK converted some of its old carriers into Commando Carriers, sea-going helicopter airfields like HMS Bulwark. To militate against the expensive connotations of the term "aircraft carrier", the new Invincible class carriers were originally designated "through deck cruisers" and were initially helicopter only craft to operate as escort carriers. The arrival of the Sea Harrier meant they could carry fixed wing aircraft despite their short flight deck.

The United Nations command began carrier operations against the North Korean Army on July 3, 1950 in response to the invasion of South Korea. Task Force 77 consisted at that time of the carriers USS Valley Forge and HMS Triumph. Before the armistice of July 27, 1953, 12 U.S. carriers served 27 tours in the Sea of Japan as part of the Task Force 77. During periods of intensive air operations as many as four carriers were on the line at the same time (see Attack on the Sui-ho Dam), but the norm was two on the line with a third "ready" carrier at Yokosuka able to respond to the Sea of Japan at short notice.

A second carrier unit, Task Force 95, served as a blockade force in the Yellow Sea off the west coast of North Korea. The task force consisted of a Commonwealth light carrier (HMSs Triumph, Theseus, Glory, Ocean, and HMAS Sydney) and usually a U.S. escort carrier (USS Badoeng Strait, Bairoko, Point Cruz, Rendova, and Sicily).

Over 301,000 carrier strikes were flown during the Korean War: 255,545 by the aircraft of Task Force 77; 25,400 by the Commonwealth aircraft of Task Force 95, and 20,375 by the escort carriers of Task Force 95. United States Navy and Marine Corps carrier-based combat losses were 541 aircraft. The Fleet Air Arm lost 86 aircraft in combat, and the Fleet Air Arm of Australia 15.

The United States Navy fought "the most protracted, bitter, and costly war" (René Francillon) in the history of naval aviation from August 2, 1964 to August 15, 1973 in the waters of the South China Sea. Operating from two deployment points (Yankee Station and Dixie Station), carrier aircraft supported combat operations in South Vietnam and conducted bombing operations in conjunction with the U.S. Air Force in North Vietnam under Operations Flaming Dart, Rolling Thunder, and Linebacker. Numbers of carriers on the line varied during differing points of the conflict, but as many as six operated at one time during Operation Linebacker.

21 aircraft carriers (all operational attack carriers during the era except John F. Kennedy) deployed to Task Force 77 of the U.S. Seventh Fleet, conducting 86 war cruises and operating 9,178 total days on the line in the Gulf of Tonkin. 530 aircraft were lost in combat and 329 more in operational accidents, causing the deaths of 377 naval aviators, with 64 others reported missing and 179 taken prisoner-of-war. 205 officers and men of the ship's complements of three carriers (Forrestal, Enterprise, and Oriskany) were killed in major shipboard fires.

During the Falklands War the United Kingdom was able to win a conflict 8,000 miles (13,000 km) from home in large part due to the use of the full size carrier HMS Hermes and the smaller HMS Invincible. The Falklands showed the value of a VSTOL aircraft — the Hawker-Siddeley Harrier (the RN Sea Harrier and press-ganged RAF Harriers) in defending the fleet and assault force from shore based aircraft and for attacking the enemy. Helicopters from the carriers were used to deploy troops and pick up the wounded.

The US has also made use of carriers in the Persian Gulf, Afghanistan and to protect its interests in the Pacific. During the 2003 invasion of Iraq US aircraft carriers served as the primary base of US air power. Even without the ability to place significant numbers of aircraft in Middle Eastern airbases, the United States was capable of carrying out significant air attacks from carrier-based squadrons. Recently, US aircraft carriers, such as the USS Ronald Reagan provided air support for counter-insurgency operations in Iraq.

Aircraft carriers are generally the largest ships operated by navies; a Nimitz class carrier powered by two nuclear reactors and four steam turbines is 1092 feet (333 m) long and costs about $4.5 billion. The United States has the majority of aircraft carriers with a dozen in service and a dozen in reserve, and its aircraft carriers are a cornerstone of American power projection capability.

Nine countries maintain a total of 25 aircraft carriers: United States, United Kingdom, France, Russia, Italy, India, Spain, Brazil, and Thailand. In addition the People's Republic of China's People's Liberation Army Navy possesses the former Soviet aircraft carrier Varyag, but most naval analysts believe that they have no intention to operate it, but instead are using Varyag to learn about carrier operations for future Chinese aircraft carriers. Canada, the People's Republic of China, Japan, Pakistan, Australia, Chile and Singapore also operate vessels capable of carrying and operating multiple helicopters.

Aircraft carriers are generally accompanied by a number of other ships, to provide protection for the relatively unwieldy carrier, to carry supplies, and to provide additional offensive capabilities. This is often termed a battle group or carrier group, sometimes a carrier battle group.

In the early 21st century, worldwide aircraft carriers are capable of carrying about 1250 aircraft. US carriers account for over 1000 of these; the second leading country, France fields around 72 aircraft. The United Kingdom and France are both undergoing a major expansion in carrier capability (with a common ship class), but the United States will still maintain a very large lead.

Several nations which currently possess aircraft carriers are in the process of planning new classes to replace current ones.

The Royal Navy is currently planning two new larger STOVL aircraft carriers (as yet only known as CVF) to replace the three Invincible class carriers currently in service. These two ships are expected to be named HMS Queen Elizabeth and HMS Prince of Wales. They will be able to operate about 50 aircraft and will have a displacement of around 60,000 tonnes. The two ships are due to enter service in 2012 and 2015 respectively. Their primary aircraft complement will be made up of F-35 Lightning IIs, and their ship's company will number around 1000.

The two ships will be the largest warships ever built for the Royal Navy. Initially to be configured for STOVL operations, the carriers are to be adaptable to allow any type of future generation of aircraft to operate from them.

In June 2005, it was reported by boxun.com that the People's Republic of China would build a US$362 million aircraft carrier with a displacement of 78,000 tonnes, to be built by the enclosed Jiangnan Shipyard in Shanghai. The ship is suppose to carry around 70 4th generation jet aircraft (may carry 5th generation jet aircraft when available) The report was denied by Chinese defence official Zhang Guangqin. Previous talks to purchase an aircraft carrier from Russia and France have not borne fruit. On March 10, 2006, People's Liberation Army Lt. Gen. Wang Zhiyuan announced that the People's Republic of China will research and build an aircraft carrier to develop a CVBG in 3 to 5 years. Observers say the first carrier would be deployed to secure energy supply lines in the South China Sea. Fighters included on the carrier may include the J-10B and a modified SU-30MKK.

The French Navy has set in motion plans for a second CTOL aircraft carrier, to supplement Charles de Gaulle. The design is to be much larger, in the range of 65-74,000 tonnes, and will not be nuclear-powered like Charles de Gaulle. There are plans to buy the third carrier of the current Royal Navy design for CATOBAR operations (the Thales/BAE Systems design for the Royal Navy is for a STOVL carrier which is reconfigurable to CATOBAR operations).

India started the construction of a 37,500 tonne, 252 meter-long Indigenous Aircraft Carrier in April 2005. The new carrier will cost US$762 million and will operate MiG 29K 'Fulcru', Naval HAL LCA and Sea Harrier aircraft along with the Indian-made helicopter HAL Dhruv. The ship will be powered by four turbine engines and when completed will have a range of 7,500 nautical miles, carrying 160 officers, 1400 sailors, and 30 aircraft. The carrier is being constructed by a state-run shipyard in southern India.

In 2004, India also bought Admiral Gorshkov from Russia for US$1.5 billion. It is most likely to be named the INS Vikramaditya, and is expected to join the Indian Navy in 2008 after a refit.

The construction of the conventional powered Marina Militare STOVL aircraft carrier Cavour began in 2001. It is being built by Fincantieri of Italy. After much delay, Cavour is expected to enter service in 2008 to complement the Marina Militare aircraft carrier Giuseppe Garibaldi. A second aircraft carrier in the 25-30,000 tonne range is much desired by the Italian Navy, to replace the already decommissioned helicopter carrier Vittorio Veneto, but for budgetary reasons all further development is on hold. It is provisionally called Alcide de Gasperi.

The Royal Australian Navy is currently investing in two Canberra class large amphibious ships, which will either be the French Mistral class or the Spanish Buque de Proyección Estratégica design. While the Navy has not considered operating fixed-wing aircraft from the ships, it has been suggested by commentators that they also operate aircraft such as the F-35B. Both to be in service by 2012.

The Russian navy has one operational aircraft carrier, Admiral Kuznetsov.

Russia is currently developing a new aircraft carrier design. They are starting from scratch to make a modern model, with the newest available materials and electronics. Requirements would be for two aircraft carriers - one each for the Russian Northern and Pacific Fleets. Construction is set to begin by 2010, and finish in around 6 years. The Ulyanovsk supercarrier design is being revised.

The project for the 231 meter-long and 25,000-30,000 tonnes conventional powered Buque de Proyección Estratégica (Strategic projection vessel) for the Spanish navy was approved in 2003, and its construction started in August 2005, with the ship-building firm Navantia in charge of the project. The Buque de proyección estratégica is a vessel designed to operate both as amphibious assault vessel and as VSTOL aircraft carrier, depending on the mission assigned. The design was made keeping in mind the low-intensity conflicts in which the Spanish Armada is likely to be involved in the future. When it is configured to operate as VSTOL aircraft carrier, the operating range will be about 25,000 tonnes, and it will operate a maximum of 30 Matador AV-8B+, F-35 or a mixed force of both aircraft. The ship is provided with a Sky-Jump and a tri-dimensional radar based combat system, and she will be the second operating aircraft carrier of the Spanish navy after Príncipe de Asturias.

(formerly CVN-21)]]

The current US Fleet of Nimitz-class carriers are to be followed into service (and in some cases replaced) by the Gerald R. Ford class (formerly CVN-21) Carrier. It is expected that the ships will be larger and will operate more aircraft than the 80 or so of Nimitz (though current Carrier air wings number about 64), and will also be designed to be less detectable by radar. The United States Navy is also looking to make these new carriers more automated in an effort to reduce the amount of funding required to build and maintain its supercarriers.