Anti-aircraft warfare
Encyclopedia
NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces wherever they are. However, for most countries the main effort has tended to be 'homeland defence'. NATO refers to airborne air defence as counter-air and naval air defence as anti-aircraft warfare. Missile defence is an extension of air defence as are initiatives to adapt air defence to the task of intercepting potentially any projectile in flight.

However, in some countries, such as Britain and Germany in World War II, the Soviet Union and NATO's European Command, ground based air defence and air defence aircraft have been under integrated command and control. Nevertheless, while overall air defence may be for homeland defence including military facilities, forces in the field, wherever they are, invariably deploy their own air defence capability if there is an air threat. A surface based air defence capability can also be deployed offensively to deny the use of airspace to an opponent.

Terminology

The term air defence was probably first used by Britain when Air Defence of Great Britain
Air Defence of Great Britain
The Air Defence of Great Britain was a RAF command comprising substantial Army and RAF elements responsible for the air defence of the British Isles...

 (ADGB) was created as a Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

 command in 1925. However, arrangements in UK were also called 'anti-aircraft', abbreviated as AA, a term that remained in general use into the 1950s. After World War I it was sometimes prefixed by 'Light' or 'Heavy' (LAA or HAA) to classify a type of gun or unit.

NATO defines anti-aircraft warfare (AAW) as "measures taken to defend a maritime force against attacks by airborne weapons launched from aircraft, ships, submarines and land-based sites." In some armies the term All-Arms Air Defence (AAAD) is used for air defence by non-specialist troops. Other terms from the late 20th century include GBAD (Ground Based AD) with related terms SHORAD (Short Range AD) and MANPADS ("Man Portable AD Systems": typically shoulder launched missiles). Anti-aircraft missiles are variously called surface-to-air missile
Surface-to-air missile
A surface-to-air missile or ground-to-air missile is a missile designed to be launched from the ground to destroy aircraft or other missiles...

, abbreviated and pronounced "SAM" and Surface to Air Guide Weapon (SAGW).

Important non-English terms for air defence include German flak (from the German
German language
German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....

 Fliegerabwehrkanone, aircraft defence cannon; also cited as Flugzeugabwehrkanone or Flugabwehrkanone) and the Russian term Protivovozdushnaya oborona (Cyrillic: Противовоздушная оборона), a literal translation of "anti-air defence", abbreviated as PVO.
Nicknames for anti-aircraft guns include AA, AAA or triple-A, an abbreviation
Abbreviation
An abbreviation is a shortened form of a word or phrase. Usually, but not always, it consists of a letter or group of letters taken from the word or phrase...

 of anti-aircraft artillery, "ack-ack" (from the World War I phonetic alphabet for AA), archie (a World War I British term probably coined by Amyas Borton
Amyas Borton
Air Vice-Marshal Amyas Eden Borton CB, CMG, DSO, AFC was a pilot and commander in the Royal Flying Corps during World War I and a senior commander in the Royal Air Force during the 1920s. He saw active service on the Western Front, in Palestine and in Iraq...

 and believed to derive via the Royal Flying Corps
Royal Flying Corps
The Royal Flying Corps was the over-land air arm of the British military during most of the First World War. During the early part of the war, the RFC's responsibilities were centred on support of the British Army, via artillery co-operation and photographic reconnaissance...

 from the music-hall comedian George Robey
George Robey
Sir George Edward Wade , better known by his stage name, George Robey, was an English music hall comedian and star. He was marketed as the "Prime Minister of Mirth".-Early life:...

's line "Archibald, certainly not!"). In Russian all AA systems called as 'zenit' (zenith) systems (guns, missiles etc.).

The maximum distance at which a gun or missile can engage an aircraft is an important figure. However, many different definitions are used but unless the same definition is used, performance of different guns or missiles cannot be compared. For AA guns only the ascending part of the trajectory can be usefully used. One term is 'ceiling', maximum ceiling being the height a projectile would reach if fired vertically, not practically usefully in itself as few AA guns are able to fire vertically, and maximum fuze duration may be too short, but potentially useful as a standard to compare different weapons. The British adopted "effective ceiling", meaning the altitude at which a gun could deliver a series of shells against a moving target; this could be constrained by maximum fuze running time as well as the gun's capability. By the late 1930s the British definition was "that height at which a directly approaching target at 400 mph can be engaged for 20 seconds before the gun reaches 70 degrees elevation". However, effective ceiling for heavy AA guns was affected by non-ballistic factors:
  • The maximum running time of the fuze, this set the maximum usable time of flight.
  • The capability of fire control instruments to determine target height at long range.
  • The precision of the cyclic rate of fire, the fuze length had to be calculated and set for where the target would be at the time of flight after firing, to do this meant knowing exactly when the round would fire.

General description

The essence of air defence is to detect hostile aircraft and destroy them. The critical issue is to hit a target moving in three-dimensional space; an attack must not only match these three coordinates, but must do so at the time the target is at that position. This means that projectiles either have to be guided to hit the target, or aimed at the predicted position of the target at the time the projectile reaches it, taking into account speed and direction of both the target and the projectile.

Throughout the 20th century air defence was one of the fastest-evolving areas of military technology, responding to the evolution of aircraft and exploiting various enabling technologies, particularly radar, guided missiles and computing (initially electromechanical analog computing from the 1930s on, as with equipment described below). Air defence evolution covered the areas of sensors and technical fire control, weapons, and command and control. At the start of the 20th century these were either very primitive or non-existent.

Initially sensors were optical and acoustic devices developed in World War I and continued into the 1930s, but were quickly superseded by radar, which in turn was supplemented by optronics in the 1980s.

Command and control remained primitive until the late 1930s, when Britain created an integrated system for ADGB that linked the ground-based air defence of the army's AA Command, although field-deployed air defence relied on less sophisticated arrangements. NATO later called these arrangements an "air defence ground environment", defined as "the network of ground radar sites and command and control centres within a specific theatre of operations which are used for the tactical control of air defence operations".

Rules of Engagement are critical to prevent air defences engaging friendly or neutral aircraft. Their use is assisted but not governed by IFF (identification friend or foe
Identification friend or foe
In telecommunications, identification, friend or foe is an identification system designed for command and control. It is a system that enables military and national interrogation systems to identify aircraft, vehicles, or forces as friendly and to determine their bearing and range from the...

) electronic devices originally introduced in World War II. While these rules originate at the highest authority, different rules can apply to different types of air defence covering the same area at the same time. AAAD usually operates under the tightest rules.

NATO calls these rules Weapon Control Orders (WCO), they are:
  • weapons free: a weapon control order imposing a status whereby weapons systems may be fired at any target not positively recognized as friendly.
  • weapons hold: a weapon control order imposing a status whereby weapons systems may only be fired in self-defence or in response to a formal order.
  • weapons tight: a weapon control order imposing a status whereby weapons systems may be fired only at targets recognized as hostile.


Until the 1950s guns firing ballistic munitions were the standard weapon; guided missiles then became dominant, except at the very shortest ranges. However, the type of shell or warhead and its fuzing and, with missiles the guidance arrangement, were and are varied. Targets are not always easy to destroy totally, although damaged aircraft may be forced to abort their mission and, even if they manage to return and land in friendly territory, may be out of action for days or permanently. Ignoring small arms and smaller machine-guns, ground-based air defence guns have varied in calibre from 20 mm to at least 149 mm.

Ground-based air defence is deployed in several ways:
  • Self-defence by ground forces using their organic weapons, AAAD.
  • Accompanying defence, specialist aid defence elements accompanying armoured or infantry units.
  • Point defence around a key target, such as a bridge, critical government building or ship.
  • Area air defence, typically 'belts' of air defence to provide a barrier, but sometimes an umbrella covering an area. Areas can vary widely in size, belts along a nation's border, e.g. the Cold War
    Cold War
    The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...

     MIM-23 Hawk
    MIM-23 Hawk
    The Raytheon MIM-23 Hawk is a U.S. medium range surface-to-air missile. The Hawk was initially designed to destroy aircraft and was later adapted to destroy other missiles in flight. The missile entered service in 1960, and a program of extensive upgrades has kept it from becoming obsolete. It was...

     and Nike belts that ran north–south across Germany, a military formation's manoeuvre area, or the area of a city or port. In ground operations air defence areas may be used offensively by rapid redeployment across current aircraft transit routes.


Air defence has included other elements, although after World War II most fell into disuse:
  • Tethered barrage balloons to deter and threaten aircraft flying below the height of the balloons, where they are susceptible to damaging collisions with steel tethers.
  • Searchlight
    Searchlight
    A searchlight is an apparatus that combines a bright light source with some form of curved reflector or other optics to project a powerful beam of light of approximately parallel rays in a particular direction, usually constructed so that it can be swiveled about.-Military use:The Royal Navy used...

    s to illuminate aircraft at night for both gun-layers and optical instrument operators. During World War II searchlights became radar controlled.
  • Large smoke screens created by large smoke canisters on the ground to screen targets and prevent accurate weapon aiming by aircraft.

Passive air defence is defined by NATO as "Passive measures taken for the physical defence and protection of personnel, essential installations and equipment in order to minimize the effectiveness of air and/or missile attack". It remains a vital activity by ground forces and includes camouflage and concealment to avoid detection by reconnaissance and attacking aircraft. Measures such as camouflaging important buildings was common in World War II. During the Cold War some airfields painted their runways and taxiways green.

Organization

While navies are invariably responsible for their own air defence, at least for ships at sea, organisational arrangements for land-based air defence vary between nations and over time.

The most extreme case was the Soviet Union, and this model may still be followed in some countries: it was a separate service, on a par with the navy or ground force. In the Soviet Union this was called Voyska PVO, and had both fighter aircraft and ground-based systems. This was divided into two arms, PVO Strany, the Strategic Air defence Service responsible for Air Defence of the Homeland, created in 1941 and becoming an independent service in 1954, and PVO SV, Air Defence of the Ground Forces. Subsequently these became part of the air force and ground forces respectively

The divided responsibility echoed Germany's arrangements in World War II, where the Luftwaffe was responsible for air defence of Germany while the army protected itself. At the other extreme the United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

 has an Air Defense Artillery
Air Defense Artillery
The Air Defense Artillery branch descended from the Anti-Aircraft Artillery into a separate branch on 20 June 1968...

 branch that provided ground-based air defence for both homeland and the army in the field. Many other nations also deploy an air-defence branch in the army.

In Britain and some other armies, the single artillery branch has been responsible for both homeland and overseas ground-based air defence, although there was divided responsibility with the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 for homeland air defence in World War I. However, in World War II the RAF Regiment
RAF Regiment
The Royal Air Force Regiment is a specialist airfield defence corps founded by Royal Warrant in 1942. After a 32 week trainee gunner course, its members are trained and equipped to prevent a successful enemy attack in the first instance; minimise the damage caused by a successful attack; and...

 was formed to protect airfields everywhere, and this included light air defences. In the later decades of the Cold War this included the United States Air Force
United States Air Force
The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...

's operating bases in UK. However, all ground-based air defence was removed from Royal Air Force (RAF) jurisdiction in 2004. The army's homeland air defence role ended in 1955, but during the 1960s and 1970s the RAF's Fighter Command operated long-range air -defence missiles to protect key areas in the UK. During World War II the Royal Marines
Royal Marines
The Corps of Her Majesty's Royal Marines, commonly just referred to as the Royal Marines , are the marine corps and amphibious infantry of the United Kingdom and, along with the Royal Navy and Royal Fleet Auxiliary, form the Naval Service...

 also provided air defence units; formally part of the mobile naval base defence organisation, they were handled as an integral part of the army-commanded ground based air defences.

The basic air defence unit is typically a battery with 2 to 12 guns or missile launchers and fire control elements. These batteries, particularly with guns, usually deploy in a small area, although batteries may be split; this is usual for some missile systems. SHORAD missile batteries often deploy across an area with individual launchers several kilometres apart. When MANPADS is operated by specialists, batteries may have several dozen teams deploying separately in small sections; self-propelled air defence guns may deploy in pairs.

Batteries are usually grouped into battalions or equivalent. In the field army a light gun or SHORAD battalion is often assigned to a manoeuvre division. Heavier guns and long-range missiles may be in air-defense brigades and come under corps or higher command. Homeland air defence may have a full military structure. For example the UK's AA Command, commanded by a full artillery general
General (United Kingdom)
General is currently the highest peace-time rank in the British Army and Royal Marines. It is subordinate to the Army rank of Field Marshal, has a NATO-code of OF-9, and is a four-star rank....

 was part of ADGB. At its peak in 1941–42 it comprised three AA corps with 12 AA divisions between them.

Earliest use

The use of balloons by the Union Army during the American Civil War compelled the Confederates to develop methods of combating them. These included the use of artillery, small arms, and saboteurs. They were unsuccessful, but internal politics led the Union's Balloon Corps
Union Army Balloon Corps
The Union Army Balloon Corps was a branch of the Union Army during the American Civil War, established by presidential appointee Thaddeus S. C. Lowe...

 to be disbanded mid-war. The Confederates experimented with balloons as well.

The earliest known use of weapons specifically made for the anti-aircraft role occurred during the Franco-Prussian War
Franco-Prussian War
The Franco-Prussian War or Franco-German War, often referred to in France as the 1870 War was a conflict between the Second French Empire and the Kingdom of Prussia. Prussia was aided by the North German Confederation, of which it was a member, and the South German states of Baden, Württemberg and...

 of 1870. After the disaster at Sedan
Battle of Sedan
The Battle of Sedan was fought during the Franco-Prussian War on 1 September 1870. It resulted in the capture of Emperor Napoleon III and large numbers of his troops and for all intents and purposes decided the war in favour of Prussia and its allies, though fighting continued under a new French...

, Paris was besieged
Siege of Paris
The Siege of Paris, lasting from September 19, 1870 – January 28, 1871, and the consequent capture of the city by Prussian forces led to French defeat in the Franco-Prussian War and the establishment of the German Empire as well as the Paris Commune....

 and French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 troops outside the city started an attempt at resupply via balloon
Balloon (aircraft)
A balloon is a type of aircraft that remains aloft due to its buoyancy. A balloon travels by moving with the wind. It is distinct from an airship, which is a buoyant aircraft that can be propelled through the air in a controlled manner....

. Gustav Krupp
Krupp
The Krupp family , a prominent 400-year-old German dynasty from Essen, have become famous for their steel production and for their manufacture of ammunition and armaments. The family business, known as Friedrich Krupp AG Hoesch-Krupp, was the largest company in Europe at the beginning of the 20th...

 mounted a modified 1-pounder (37mm) gun — the ballonkanone — on top of a horse-drawn carriage for the purpose of shooting down these balloons.
By the early 20th century balloon, or airship, guns, for land and naval use were attracting attention. Various types of ammunition were proposed, high explosive, incendiary, bullet-chains, rod bullets and shrapnel. The need for some form of tracer or smoke trail was articulated. Fuzing options were also examined, both impact and time types. Mountings were generally pedestal type, but could be on field platforms. Trials were underway in most countries in Europe but only Krupp, Erhardt, Vickers
Vickers
Vickers was a famous name in British engineering that existed through many companies from 1828 until 1999.-Early history:Vickers was formed in Sheffield as a steel foundry by the miller Edward Vickers and his father-in-law George Naylor in 1828. Naylor was a partner in the foundry Naylor &...

 Maxim, and Schneider had published any information by 1910. Krupp's designs included adaptations of their 65 mm 9-pounder, a 75 mm 12-pounder, and even a 105 mm gun. Erhardt also had a 12-pounder, while Vickers Maxim offered a 3-pounder and Schneider a 47 mm. The French balloon gun appeared in 1910, it was an 11-pounder but mounted on a vehicle, with a total uncrewed weight of 2 tons. However, since balloons were slow moving, sights were simple. But the challenges of faster moving airplanes were recognized.

By 1913 only France and Germany had developed field guns suitable for engaging balloons and aircraft and addressed issues of military organization. Britain's Royal Navy would soon introduce the QF 3-inch
QF 3 inch 20 cwt
The QF 3 inch 20 cwt anti-aircraft gun became the standard anti-aircraft gun used in the home defence of the United Kingdom against German airships and bombers and on the Western Front in World War I. It was also common on British warships in World War I and submarines in World War II...

 and QF 4-inch
QF 4 inch Mk V naval gun
The QF 4 inch Mk V gun was a Royal Navy gun of World War I which was adapted on HA mountings to the heavy anti-aircraft role both at sea and on land, and was also used as a coast defence gun.-Naval service:...

 AA guns and also had Vickers 1-pounder quick firing "pom-pom"s
QF 1 pounder pom-pom
The QF 1 pounder, universally known as the pom-pom, was an early 37 mm British autocannon. It was used by several countries initially as an infantry gun and later as a light anti-aircraft gun. The name comes from the sound it makes when firing....

 that could be used in various mountings.

World War I

By the start of World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, the 75 mm had become the standard German weapon, and came mounted on a large traverse that could be easily picked up on a wagon for movement.
The British immediately recognised the issue, and as their first priority was defence of the British Isles, guns were quickly deployed to defend key targets in the London area. By December 1914 the Royal Naval Volunteer Reserve (RNVR) was manning AA guns and searchlights assembled from various sources at some nine ports. The Royal Garrison Artillery
Royal Garrison Artillery
The Royal Garrison Artillery was an arm of the Royal Artillery that was originally tasked with manning the guns of the British Empire's forts and fortresses, including coastal artillery batteries, the heavy gun batteries attached to each infantry division, and the guns of the siege...

 (RGA) was given responsibility for AA defence in the field, using motorised two-gun sections. The first were formally formed in November 1914. Initially they used QF 1 pounder "pom-pom"
QF 1 pounder pom-pom
The QF 1 pounder, universally known as the pom-pom, was an early 37 mm British autocannon. It was used by several countries initially as an infantry gun and later as a light anti-aircraft gun. The name comes from the sound it makes when firing....

 (a 37 mm version of the Maxim Gun
Maxim gun
The Maxim gun was the first self-powered machine gun, invented by the American-born British inventor Sir Hiram Maxim in 1884. It has been called "the weapon most associated with [British] imperial conquest".-Functionality:...

).

All armies soon deployed AA guns often based on their smaller field pieces, notably the French 75 mm and Russian 76.2 mm, typically simply propped up on some sort of embankment to get the muzzle pointed skyward. The British Army
British Army
The British Army is the land warfare branch of Her Majesty's Armed Forces in the United Kingdom. It came into being with the unification of the Kingdom of England and Scotland into the Kingdom of Great Britain in 1707. The new British Army incorporated Regiments that had already existed in England...

 adopted the 13-pounder quickly producing new mountings suitable for AA use, the 13-pdr QF 6 cwt Mk III
QF 13 pounder 6 cwt AA gun
The Ordnance QF 13 pounder Mk III anti-aircraft gun, also known as 13 pounder 6 cwt, was an early British improvisation in World War I to adapt the 13 pounder field gun to anti-aircraft use...

 was issued in 1915. It remained in service throughout the war but 18-pdr guns were lined down to take the 13-pdr shell with a larger cartridge producing the 13-pr QF 9 cwt
QF 13 pounder 9 cwt
The 13 pounder 9 cwt anti-aircraft gun became the standard mobile British anti-aircraft gun of the World War I era, especially in theatres outside Britain...

 and these proved much more satisfactory. However, In general, these ad-hoc solutions proved largely useless. With little experience in the role, no means of measuring target, range, height or speed the difficulty of observing their shell bursts relative to the target gunners proved unable to get their fuze setting correct and most rounds burst well below their targets (discovering this, British fliers gave German anti-aircraft fire the mocking nickname, "Archie"). The exception to this rule were the guns protecting spotting balloons, in which case the altitude could be accurately measured from the length of the cable holding the balloon.

The first issue was ammunition. Before the war it was recognised that ammunition needed to explode in the air. Both high explosive (HE) and shrapnel were used, mostly the former. Airburst fuzes were either igniferious (based on a burning fuse) or mechanical (clockwork). Igniferious fuzes were not well suited for anti-aircraft use. The fuze length was determined by time of flight, but the burning rate of the gunpowder is affected by altitude. The British pom-poms had only contact-fused ammunition. Zeppelins, being hydrogen filled balloons, were targets for incendiary shells and the British introduced these with airburst fuzes, both shrapnel type-forward projection of incendiary 'pot' and base ejection of an incendiary stream. The British also fitted tracers to their shells for use at night. Smoke shells were also available for some AA guns, these bursts were used as targets during training.

German air attacks on the British Isles increased in 1915 and the AA efforts were deemed somewhat ineffective, so a Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 gunnery expert, Admiral Sir Percy Scott
Percy Scott
Admiral Sir Percy Moreton Scott, 1st Baronet GCB KCVO was a British Royal Navy officer and a pioneer in modern naval gunnery.-Early years:...

, was appointed to make improvements, particularly an integrated AA defence for London. The air defences were expanded with more RNVR AA guns, 75 mm and 3-inch, the pom-poms being ineffective. The naval 3-inch was also adopted by the army, the QF 3 inch 20 cwt
QF 3 inch 20 cwt
The QF 3 inch 20 cwt anti-aircraft gun became the standard anti-aircraft gun used in the home defence of the United Kingdom against German airships and bombers and on the Western Front in World War I. It was also common on British warships in World War I and submarines in World War II...

 (76 mm), a new field mounting was introduced in 1916. Since most attacks were at night, searchlights were soon used, and acoustic methods of detection and locating were developed. By December 1916 there were 183 AA Sections defending Britain (most with the 3-inch), 74 with the BEF in France and 10 in the Middle East.

AA gunnery was a difficult business. The problem was of successfully aiming a shell to burst close to its target's future position, with various factors affecting the shells' predicted trajectory. This was called deflection gun-laying, 'off-set' angles for range and elevation were set on the gunsight and updated as their target moved. In this method when the sights were on the target, the barrel was pointed at the target's future position. Range and height of the target determined fuze length. The difficulties increased as aircraft performance improved.

The British dealt with range measurement first, when it was realised that range was the key to producing a better fuze setting. This led to the Height/Range Finder (HRF), the first model being the Barr & Stroud UB2, a 2-metre optical coincident rangefinder
Coincidence rangefinder
A coincidence rangefinder is a type of rangefinder that uses mechanical and optical principles to allow an operator to determine the distance to a visible object....

 mounted on a tripod. It measured the distance to the target and the elevation angle, which together gave the height of the aircraft. These were complex instruments and various other methods were also used. The HRF was soon joined by the Height/Fuze Indicator (HFI), this was marked with elevation angles and height lines overlaid with fuze length curves, using the height reported by the HRF operator, the necessary fuze length could be read off.

However, the problem of deflection settings — 'aim-off' — required knowing the rate of change in the target's position. Both France and UK introduced tachymetric devices to track targets and produce vertical and horizontal deflection angles. The French Brocq system was electrical, the operator entered the target range and had displays at guns; it was used with their 75 mm. The British Wilson-Dalby gun director used a pair of trackers and mechanical tachymetry; the operator entered the fuze length, and deflection angles were read from the instruments.

The German Krupp 75 mm guns were supplied with an optical sighting system that improved their capabilities. The German Army also adapted a revolving cannon that came to be known to Allied fliers as the "flaming onion
Flaming onion
The flaming onion was a 37 mm revolving-barrel anti-aircraft gun used by the German army during World War I, the name referring to both the gun, and especially the flares it fired. The American 'balloon-buster' ace, Frank Luke, was a prominent victim of this device, and it was mentioned in...

" from the shells in flight. This gun had five barrels that quickly launched a series of 37 mm artillery shells.

As aircraft started to be used against ground targets on the battlefield, the AA guns could not be traversed quickly enough at close targets and, being relatively few, were not always in the right place (and were often unpopular with other troops), so changed positions frequently. Soon the forces were adding various machine-gun based weapons mounted on poles. These short-range weapons proved more deadly, and the "Red Baron
Manfred von Richthofen
Manfred Albrecht Freiherr von Richthofen , also widely known as the Red Baron, was a German fighter pilot with the Imperial German Army Air Service during World War I...

" is believed to have been shot down by an anti-aircraft Vickers machine gun
Vickers machine gun
Not to be confused with the Vickers light machine gunThe Vickers machine gun or Vickers gun is a name primarily used to refer to the water-cooled .303 inch machine gun produced by Vickers Limited, originally for the British Army...

. When the war ended, it was clear that the increasing capabilities of aircraft would require better means of acquiring targets and aiming at them. Nevertheless a pattern had been set: anti-aircraft weapons would be based around heavy weapons attacking high-altitude targets and lighter weapons for use when they came to lower altitudes.

Inter-war years

World War I demonstrated that aircraft could be an important part of the battlefield, but in some nations it was the prospect of strategic air attack that was the main issue, presenting both a threat and an opportunity. The experience of four years of air attacks on London by Zeppelins and Gotha bombers had particularly influenced the British and was one of if not the main driver for forming an independent air force. As the capabilities of aircraft and their engines improved it was clear that their role in future war would be even more critical as their range and weapon load grew. However, in the years immediately after World War I the prospect of another major war seemed remote, particularly in Europe where the most militarily capable nations were, and little financing was available.

Four years of war had seen the creation of a new and technically demanding branch of military activity. Air defence had made huge advances, albeit from a very low starting point. However, it was new and often lacked influential 'friends' in the competition for a share of limited defence budgets. Demobilisation meant that most AA guns were taken out of service, leaving only the most modern.

However, there were lessons to be learned. In particular the British, who had had AA guns in most theatres in action in daylight and used them against night attacks at home. Furthermore they had also formed an AA Experimental Section during the war and accumulated a lot of data that was subjected to extensive analysis. As a result they published, in 1924–5, the two volume Textbook of Anti-Aircraft Gunnery. It included five key recommendations for HAA equipment:
  • Shells of improved ballistic shape with HE fillings and mechanical time fuzes.
  • Higher rates of fire assisted by automation.
  • Height finding by long-base optical instruments.
  • Centralised control of fire on each gun position, directed by tachymetric instruments incorporating the facility to apply corrections of the moment for meteorological and wear factors.
  • More accurate sound-location for the direction of searchlights and to provide plots for barrage fire.

Two assumptions underpinned the British approach to HAA fire; first, aimed fire was the primary method and this was enabled by predicting gun data from visually tracking the target and having its height. Second, that the target would maintain a steady course, speed and height. This HAA was to engage targets up to 24,000 feet. Mechanical, as opposed to igniferous, time fuzes were required because the speed of powder burning varied with height so fuze length was not a simple function of time of flight. Automated fire ensured a constant rate of fire that made it easier to predict where each shell should be individually aimed.

In 1925 the British adopted a new instrument developed by Vickers. It was a mechanical analogue computer Predictor AA No 1. Given the target height its operators tracked the target and the predictor produced bearing, quadrant elevation and fuze setting. These were passed electrically to the guns where they were displayed on repeater dials to the layers who 'matched pointers' (target data and the gun's actual data) to lay the guns. This system of repeater electrical dials built on the arrangements introduced by British coast artillery in the 1880s, and coast artillery was the background of many AA officers. Similar systems were adopted in other countries and for example the later Sperry device, designated M3A3 in the US was also used by Britain as the Predictor AA No 2. Height finders were also increasing in size, in Britain, the World War I Barr & Stroud UB 2 (7 feet optical base) was replaced by the UB 7 (9 feet optical base) and the UB 10 (18 feet optical base, only used on static AA sites). Goertz in Germany and Levallois in France produced 5 metre instruments. However, in most countries the main effort in HAA guns until the mid-1930s was improving existing ones, although various new designs were on drawing boards.

From the early 1930s eight countries developed radar
History of radar
The history of radar starts with experiments by Heinrich Hertz in the late 19th century that showed that radio waves were reflected by metallic objects. This possibility was suggested in James Clerk Maxwell's seminal work on electromagnetism...

, these developments were sufficiently advanced by the late 1930s for development work on sound locating acoustic devices
Sound ranging
In land warfare, sound ranging is a method of determining the coordinates of a hostile artillery battery using data derived from the sound of its guns firing...

 to be generally halted, although equipment was retained. Furthermore in Britain the volunteer Observer Corps
Royal Observer Corps
The Royal Observer Corps was a civil defence organisation operating in the United Kingdom between 29 October 1925 and 31 December 1995, when the Corps' civilian volunteers were stood down....

 formed in 1925 provided a network of observation posts to report hostile aircraft flying over Britain. Initially radar was used for airspace surveillance to detect approaching hostile aircraft. However, the German Würzburg radar
Würzburg radar
The Würzburg radar was the primary ground-based gun laying radar for both the Luftwaffe and the German Army during World War II. Initial development took place before the war, entering service in 1940. Eventually over 4,000 Würzburgs of various models were produced...

 was capable of providing data suitable for controlling AA guns and the British AA No 1 Mk 1 GL radar was designed to be used on AA gun positions.

The Treaty of Versailles
Treaty of Versailles
The Treaty of Versailles was one of the peace treaties at the end of World War I. It ended the state of war between Germany and the Allied Powers. It was signed on 28 June 1919, exactly five years after the assassination of Archduke Franz Ferdinand. The other Central Powers on the German side of...

 prevented Germany having AA weapons, and for example, the Krupps designers joined Bofors in Sweden. Some World War I guns were retained and some covert AA training started in the late 1920s. Germany introduced the 8.8 cm FlaK 18 in 1933, 36 and 37 models followed with various improvements but ballistic performance was unchanged. In the late 1930s the 10.5 cm FlaK 38 appeared soon followed by the 39, this was designed primarily for static sites but had a mobile mounting and the unit had 220v 24 kW generators. In 1938 design started on the 12.8 cm FlaK.

The USSR introduced a new 76 mm M1931 in the early 1930s and an 85 mm M1938 towards the end of the decade.

Britain had successful tested a new HAA gun, 3.6-inch, in 1918. In 1928 3.7-inch became the preferred solution, but it took 6 years to gain funding. Production of the QF 3.7-inch (94 mm) began in 1937; this gun was used both on mobile carriages with the field army and transportable guns on fixed mountings for static positions. At the same time the Royal Navy adopted a new 4.5-inch (114 mm) gun in a twin turret, which the army adopted in simplified single-gun mountings for static positions, mostly around ports where naval ammunition was available. However, the performance of both 3.7 and 4.5-in guns was limited by their standard fuze No 199, with a 30 second running time, although a new mechanical time fuze giving 43 seconds was nearing readiness. In 1939 a Machine Fuze Setter was introduced to eliminate manual fuze setting.

The US ended World War I with two 3-inch AA guns and improvements were developed throughout the inter-war period. However, in 1924 work started on a new 105 mm static mounting AA gun, but only a few were produced by the mid-1930s because by this time work had started on the 90 mm AA gun, with mobile carriages and static mountings able to engage air, sea and ground targets. The M1 version was approved in 1940. During the 1920s there was some work on a 4.7-inch which lapsed, but revived in 1937, leading to a new gun in 1944.

While HAA and is associated target acquisition and fire control was the primary focus of AA efforts, low-level close-range targets remained and by the mid-1930s were becoming an issue.

Until this time the British, at RAF insistence, continued their World War I use of machine guns, and introduced twin MG mountings for AAAD. The army was forbidden from considering anything larger than .50-inch. However, in 1935 their trials showed that the minimum effective round was an impact fuzed 2 lb HE shell. The following year they decided to adopt the Bofors 40 mm
Bofors 40 mm gun
The Bofors 40 mm gun is an anti-aircraft autocannon designed by the Swedish defence firm of Bofors Defence...

 and a twin barrel Vickers 2-pdr
QF 2 pounder naval gun
The 2-pounder gun, officially designated the QF 2-pounder and universally known as the pom-pom, was a 1.575 inch British autocannon, used famously as an anti-aircraft gun by the Royal Navy. The name came from the sound that the original models make when firing...

 (40 mm) on a modified naval mount. The air-cooled Bofors was vastly superior for land use, being much lighter than the water-cooled pom-pom, and UK production of the Bofors 40 mm was licensed. The Predictor AA No 3
Kerrison Predictor
The Kerrison Predictor was one of the first fully automated anti-aircraft fire-control systems. The predictor could aim a gun at an aircraft based on simple inputs like the observed speed and the angle to the target...

, as the Kerrison Predictor was officially known, was introduced with it.

The 40 mm Bofors had become available in 1931. In the late 1920s the Swedish Navy
Swedish Navy
The Royal Swedish Navy is the naval branch of the Swedish Armed Forces. It is composed of surface and submarine naval units – the Fleet – as well as marine units, the so-called Amphibious Corps .In Swedish, vessels of the Swedish Navy are given the prefix "HMS," short for Hans/Hennes...

 had ordered the development of a 40 mm naval anti-aircraft gun from the Bofors
Bofors
The name Bofors has been associated with the iron industry for more than 350 years.Located in Karlskoga, Sweden, the company originates from the hammer mill "Boofors" founded 1646. The modern corporate structure was created in 1873 with the foundation of Aktiebolaget Bofors-Gullspång...

 company. It was light, rapid-firing and reliable, and a mobile version on a four-wheel carriage was soon developed. Known simply as the 40 mm
Bofors 40 mm gun
The Bofors 40 mm gun is an anti-aircraft autocannon designed by the Swedish defence firm of Bofors Defence...

, it was adopted by some 17 different nations just before World War II and is still in use today in some applications such as on coastguard frigates.

Rheinmetall in Germany developed an automatic 20 mm in the 1920s and Oerlikon in Switzerland had acquired the patent to an automatic 20 mm gun designed in Germany during World War I. Germany introduced the rapid-fire 2 cm FlaK 30
2 cm FlaK 30
The Flak 30 and improved Flak 38 were 20 mm anti-aircraft guns used by various German forces throughout the Second World War. It was not only the primary German light anti-aircraft gun, but by far the most numerously produced German artillery piece throughout the war...

 and later in the decade it was redesigned by Mauser-Werke and became the 2 cm FlaK 38. Nevertheless, while 20 mm was better than a machine gun and mounted on a very small trailer made it easy to move, its effectiveness was limited. Germany therefore added a 3.7 cm. The first, the 3.7 cm FlaK 18 developed by Rheinmetall in the early 1930s, was basically an enlarged 2 cm FlaK 30. It was introduced in 1935 and production stopped the following year. A redesigned gun 3.7 cm FlaK 36 entered service in 1938, it too had a two-wheel carriage. However, by the mid 1930s the Luftwaffe realised that there was still a coverage gap between 3.7 cm and 8.8 cm guns. They started development of a 5 cm gun on a four-wheel carriage.

After World War I the US Army started developing a dual-role (AA/ground) automatic 37 mm cannon, designed by John M. Browning. It was standardised in 1927 as the T9 AA cannon, bu trials quickly revealed that it was worthless in the ground role. However, while the shell was a bit light (well under 2 lbs) it had a good effective ceiling and fired 125 rounds per minute; an AA carriage was developed and it entered service in 1939. The Browning 37mm proved prone to jamming, and was eventually replaced in AA units by the Bofors 40 mm. The Bofors had attracted attention from the US Navy, but none were acquired before 1939. Also, in 1931 the US Army worked on a mobile antiaircraft machine mount on the back of a heavy truck having four .30 caliber water-cooled machine guns and an optical director. It proved unsuccessful and was abandoned.

The Soviet Union also used a 37 mm, the 37 mm M1939, which appears to have been copied from the Bofors 40 mm. A Bofors 25 mm, essentially a scaled down 40 mm, was also copied as the 25 mm M1939
25 mm automatic air defense gun M1940 (72-K)
25 mm automatic air defense gun M1940 was a Soviet 25 mm caliber anti-aircraft gun. The gun was created in the beginning of 1940 at 8th Kalinin Artillery Plant in Kaliningrad under the guidance of its Chief Designer Mikhail Loginov....

.

During the 1930s solid fuel rockets were under development in the Soviet Union and Britain. In Britain the interest was for anti-aircraft fire, it quickly became clear that guidance would be required for precision. However, rockets, or 'unrotated projectiles' as they were called could the used for anti-aircraft barrages. A 2-inch rocket using HE or wire obstacle warheads was introduced first to deal with low-level or dive bombing attacks on smaller targets such as airfields. The 3-inch was in development at the end of the inter-war period.

World War II

Germany's high-altitude needs were originally going to be filled by a 75 mm gun from Krupp, designed in collaboration with their Swedish counterpart Bofors
Bofors
The name Bofors has been associated with the iron industry for more than 350 years.Located in Karlskoga, Sweden, the company originates from the hammer mill "Boofors" founded 1646. The modern corporate structure was created in 1873 with the foundation of Aktiebolaget Bofors-Gullspång...

, but the specifications were later amended to require much higher performance. In response Krupp's engineers presented a new 88 mm design, the FlaK 36
88 mm gun
The 88 mm gun was a German anti-aircraft and anti-tank artillery gun from World War II. It was widely used by Germany throughout the war, and was one of the most recognizable German weapons of the war...

. The eighty-eight would go on to become one of the most famous artillery
Artillery
Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

 pieces in history. First used in Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

 during the Spanish Civil War
Spanish Civil War
The Spanish Civil WarAlso known as The Crusade among Nationalists, the Fourth Carlist War among Carlists, and The Rebellion or Uprising among Republicans. was a major conflict fought in Spain from 17 July 1936 to 1 April 1939...

, the gun proved to be one of the best anti-aircraft guns in the world, as well as particularly deadly against light and medium tanks.
After the Dambusters
Operation Chastise
Operation Chastise was an attack on German dams carried out on 16–17 May 1943 by Royal Air Force No. 617 Squadron, subsequently known as the "Dambusters", using a specially developed "bouncing bomb" invented and developed by Barnes Wallis...

 raid in 1943 an entirely new system was developed that was required to knock down any low-flying aircraft with a single hit. The first attempt to produce such a system used a 50 mm gun, but this proved inaccurate and a new 55 mm gun replaced it. The system used a centralised control system including both search and targeting radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

, which calculated the aim point for the guns after considering windage and ballistics, and then sent electrical commands to the guns, which used hydraulics to point themselves at high speeds. Operators simply fed the guns and selected the targets. This system, modern even by today's standards, was in late development when the war ended.

The British had already arranged license building of the 40 mm Bofors gun, and introduced these into service. These had the power to knock down aircraft of any size, yet were light enough to be mobile and easily swung. The gun became so important to the British war effort that they even produced a movie, The Gun, that encouraged workers on the assembly line to work harder. The Imperial measurement production drawings the British had developed were supplied to the Americans who produced their own (unlicensed) copy of the 40 mm at the start of the war, moving to licensed production in mid-1941.

Service trials demonstrated another problem however: that ranging and tracking the new high-speed targets was almost impossible. At short range, the apparent target area is relatively large, the trajectory is flat and the time of flight is short, allowing to correct lead by watching the tracers. At long range, the aircraft remains in firing range for a long time, so the necessary calculations can in theory be done by slide rules - though, because small errors in distance cause large errors in shell fall height and detonation time, exact ranging is crucial.
For the ranges and speeds that the Bofors worked at, neither solution was good enough.
The solution was automation
Automation
Automation is the use of control systems and information technologies to reduce the need for human work in the production of goods and services. In the scope of industrialization, automation is a step beyond mechanization...

, in the form of a mechanical computer, the Kerrison Predictor
Kerrison Predictor
The Kerrison Predictor was one of the first fully automated anti-aircraft fire-control systems. The predictor could aim a gun at an aircraft based on simple inputs like the observed speed and the angle to the target...

. Operators kept it pointed at the target, and the Predictor then calculated the proper aim point automatically and displayed it as a pointer mounted on the gun. The gun operators simply followed the pointer and loaded the shells. The Kerrison was fairly simple, but it pointed the way to future generations that incorporated radar, first for ranging and later for tracking. Similar predictor systems were introduced by Germany during the war, also adding radar ranging as the war progressed.

Although they receive little attention, US Army anti-aircraft systems were actually quite competent. Their smaller tactical needs were filled with four M2 .50 caliber
.50 BMG
The .50 Browning Machine Gun or 12.7×99mm NATO is a cartridge developed for the Browning .50 caliber machine gun in the late 1910s. Entering service officially in 1921, the round is based on a greatly scaled-up .30-06 cartridge...

 machine guns linked together (known as the "Quad Fifty"), which were often mounted on the back of a half-track
Half-track
A half-track is a civilian or military vehicle with regular wheels on the front for steering, and caterpillar tracks on the back to propel the vehicle and carry most of the load. The purpose of this combination is to produce a vehicle with the cross-country capabilities of a tank and the handling...

 to form the Half Track, M16 GMC, Anti-Aircraft. Although of less power than Germany's 20 mm systems, the typical 4 or 5 combat batteries of a typical Army AAA battalion were often spread many kilometers apart from each other, rapidly attaching and detaching to larger ground combat units to provide welcome defense from enemy aircraft.

AAA battalions were also used to help suppress ground targets. Their larger 90 mm M3 gun would prove, as did the eighty-eight, to make an excellent anti-tank gun as well, and was widely used late in the war in this role. For smaller targets, the U.S. Army made use of its Quad-4 halftracks, which were truck-mounted turrets equipped with 4 parallel-mounted 50 mm machine guns. These weapons, though few in number, played a significant role in beating back the Germans in the Battle of the Bulge. Attached or nearby General Patton's Third Army when he began his unprecedented race to Bastogne, about a dozen Quad-50 units were used to, among other tasks, literally open up "holes" in the dense forest with their 4 parallel machine guns through which some minimal visibility was made possible. Also available to the Americans at the start of the war was the 120 mm M1 gun
120 mm M1 gun
The 120 mm Gun M1 was the United States Army's standard super-heavy anti-aircraft gun, complementing the smaller and more mobile 90 mm M3 in service. Its maximum altitude was about , which garnered it the nickname the stratosphere gun. The 120 served primarily in U.S. defensive roles, although...

 stratosphere gun, which was the most powerful AA gun with an impressive 60000 ft (18.3 km) altitude capability. No 120 M1 was ever fired at an enemy aircraft. The 90 mm and 120 mm guns would continue to be used into the 1950s.

The US Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 had also put some thought into the problem, and came up with the 1.1"/75 (28mm) gun to replace the inadequate .50 caliber. This weapon had the teething troubles that most new weapons have, but the issues with the gun were never sorted out. It was replaced by the Bofors 40 mm
Bofors 40 mm gun
The Bofors 40 mm gun is an anti-aircraft autocannon designed by the Swedish defence firm of Bofors Defence...

 wherever possible. The 5"/38 caliber gun turned out to be an excellent anti-aircraft weapon, once the Proximity fuze
Proximity fuze
A proximity fuze is a fuze that is designed to detonate an explosive device automatically when the distance to target becomes smaller than a predetermined value or when the target passes through a given plane...

 had been perfected.
The Germans developed massive reinforced concrete blockhouse
Blockhouse
In military science, a blockhouse is a small, isolated fort in the form of a single building. It serves as a defensive strong point against any enemy that does not possess siege equipment or, in modern times, artillery...

s, some more than six stories high, which were known as Hochbunker "High Bunkers" or "Flaktürme" flak tower
Flak tower
Flak towers were 8 complexes of large, above-ground, anti-aircraft gun blockhouse towers constructed in the cities of Berlin , Hamburg , and Vienna from 1940 onwards....

s, on which they placed anti-aircraft artillery. Those in cities attacked by the Allied land forces became fortresses. Several in Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

 were some of the last buildings to fall to the Soviets during the Battle of Berlin
Battle of Berlin
The Battle of Berlin, designated the Berlin Strategic Offensive Operation by the Soviet Union, was the final major offensive of the European Theatre of World War II....

 in 1945. The British built structures in the Thames Estuary
Thames Estuary
The Thames Mouth is the estuary in which the River Thames meets the waters of the North Sea.It is not easy to define the limits of the estuary, although physically the head of Sea Reach, near Canvey Island on the Essex shore is probably the western boundary...

 and other tidal areas upon which they based guns. After the war most were left to rot. Some were outside territorial waters, and had a second life in the 1960s as platforms for pirate radio stations.
During World War II, the use of rocket-powered missiles for shooting down aircraft began. Research was conducted mostly by the US, Britain and Germany. The first step was unguided missile systems like the British 2 inch RP, which was fired in large numbers from Z batteries. The firing of one of these devices during an air raid is suspected to have caused the Bethnal Green disaster in 1943. Facing the threat of Japanese Kamikaze
Kamikaze
The were suicide attacks by military aviators from the Empire of Japan against Allied naval vessels in the closing stages of the Pacific campaign of World War II, designed to destroy as many warships as possible....

 attacks the British and US developed surface-to-air rockets like British Stooge
Fairey Stooge
Fairey Aviation's Stooge was a command guided surface-to-air missile development project carried out in the United Kingdom starting in World War II. Development dates to a British Army request from 1944, but the work was taken over by the Royal Navy as a potential counter to the Kamikaze threat...

 or the American Lark
Lark
Larks are passerine birds of the family Alaudidae. All species occur in the Old World, and in northern and eastern Australia; only one, the Shore Lark, has spread to North America, where it is called the Horned Lark...

 as counter measures, but none of them were ready at the end of the war. The Germans missile research was the most advanced of the war as the Germans put considerable effort in the research and development of rocket systems for all purposes. Among them were several guided and unguided systems. Unguided systems involved the Fliegerfaust
Fliegerfaust
The Fliegerfaust , also known as the "Luftfaust" , was a prototype unguided German multi-barreled ground-to-air rocket launcher designed to destroy enemy ground attack planes.- Overview :...

 as the first MANPADS. Guided systems were several sophisticated radio, wire, or radar guided missiles like the Wasserfall
Wasserfall
The Wasserfall Ferngelenkte Flakrakete , was a World War II guided surface-to-air missile developed at Peenemünde, Germany.-Technical characteristics:...

 rocket. Due to the severe war situation for Germany all of those systems were only produced in small numbers and most of them were only used by training or trial units.

Another aspect of anti-aircraft defense was the use of barrage balloon
Barrage balloon
A barrage balloon is a large balloon tethered with metal cables, used to defend against low-level aircraft attack by damaging the aircraft on collision with the cables, or at least making the attacker's approach more difficult. Some versions carried small explosive charges that would be pulled up...

s to act as physical obstacle initially to bomber aircraft over cities and later for ground attack aircraft over the Normandy invasion fleets. The balloon, a simple blimp tethered to the ground, worked in two ways. Firstly, it and the steel cable were a danger to any aircraft that tried to fly among them. Secondly, to avoid the balloons, bombers had to fly at a higher altitude, which was more favorable for the guns. Barrage balloons were limited in application, and had minimal success at bringing down aircraft, being largely immobile and passive defenses.

Post-war

Post-war analysis demonstrated that even with newest anti-aircraft systems employed by both sides, the vast majority of bombers reached their targets successfully, on the order of 90%. This was bad enough during the war, but the introduction of the nuclear bomb upset things considerably. Now even a single bomber reaching the target would be unacceptable.

The developments during World War II continued for a short time into the post-war period as well. In particular the US Army set up a huge air defence network around its larger cities based on radar-guided 90 mm and 120 mm guns. But, given the general lack of success of guns against even propeller bombers, it was clear that any defence was going to have to rely almost entirely on interceptor aircraft
Interceptor aircraft
An interceptor aircraft is a type of fighter aircraft designed specifically to prevent missions of enemy aircraft, particularly bombers and reconnaissance aircraft. Interceptors generally rely on high speed and powerful armament in order to complete their mission as quickly as possible and set up...

. Despite this, US efforts continued into the 1950s with the 75 mm Skysweeper
Skysweeper
Skysweeper was an anti-aircraft gun deployed in the early 1950s by both the U.S. Army and U.S. Air Force...

 system, an almost fully automated system including the radar, computers, power, and auto-loading gun on a single powered platform. The Skysweeper replaced all smaller guns then in use in the Army, notably the 40 mm Bofors.

Things changed with the introduction of the guided missile. Although Germany had been desperate to introduce them during the war, none of them went operational during the war. With a few years of development, however, these systems started to mature into practical weapons. The US started an upgrade of their defenses using the Nike Ajax missile, and soon the larger anti-aircraft guns disappeared. The same thing occurred in the USSR
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 after the introduction of their SA-2 Guideline systems.

As this process continued, the missile found itself being used for more and more of the roles formerly filled by guns. First to go were the large weapons, replaced by equally large missile systems of much higher performance. Smaller missiles soon followed, eventually becoming small enough to be mounted on armored cars and tank chassis. These started replacing, or at least supplanting, similar gun-based SPAAG systems in the 1960s, and by the 1990s had replaced almost all such systems in modern armies. Man-portable missiles, MANPADs as they are known today, were introduced in the 1960s and have supplanted or even replaced even the smallest guns in most advanced armies.

In the 1982 Falklands War
Falklands War
The Falklands War , also called the Falklands Conflict or Falklands Crisis, was fought in 1982 between Argentina and the United Kingdom over the disputed Falkland Islands and South Georgia and the South Sandwich Islands...

, the Argentine armed forces deployed the newest west European weapons including the Oerlikon GDF-002 35 mm twin cannon
Oerlikon 35 mm twin cannon
The Oerlikon 35 mm twin cannon is a towed anti-aircraft gun made by Oerlikon Contraves . The system was originally designated as 2 ZLA/353 ML but this was later changed to GDF-001...

 and SAM Roland, while the British forces used the brand-new FIM-92 Stinger
FIM-92 Stinger
The FIM-92 Stinger is a personal portable infrared homing surface-to-air missile , which can be adapted to fire from ground vehicles and helicopters , developed in the United States and entered into service in 1981. Used by the militaries of the U.S...

. Both sides also used the Blowpipe missile
Blowpipe missile
The Shorts Blowpipe is a man-portable surface-to-air missile which was in use with the British Army and Royal Marines from 1975. It was superseded by an interim design, Javelin, and later the greatly improved Starstreak missile.-Description:...

.

During the 2008 South Ossetia war
2008 South Ossetia war
The 2008 South Ossetia War or Russo-Georgian War was an armed conflict in August 2008 between Georgia on one side, and Russia and separatist governments of South Ossetia and Abkhazia on the other....

 air power faced off against powerful SAM systems, like the 1980s Buk-M1.

AA warfare systems

Although the firearms used by the infantry can be used to engage air targets, on occasion with notable success, their effectiveness is generally limited to long-term attrition rather than preventing individual aircraft from completing weapon delivery. Speed and altitude of modern jet aircraft limit target opportunities, and critical systems may be armored in aircraft designed for the ground attack role. Adaptations of the standard autocannon
Autocannon
An autocannon or automatic cannon is a rapid-fire projectile weapon firing a shell as opposed to the bullet fired by a machine gun. Autocannons often have a larger caliber than a machine gun . Usually, autocannons are smaller than a field gun or other artillery, and are mechanically loaded for a...

, originally intended for air-to-ground use, and heavier artillery
Artillery
Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

 systems were commonly used for most anti-aircraft gunnery, starting with standard pieces on new mountings, and evolving to specially designed guns with much higher performance prior to World War II. The ammunition and shells
Shell (projectile)
A shell is a payload-carrying projectile, which, as opposed to shot, contains an explosive or other filling, though modern usage sometimes includes large solid projectiles properly termed shot . Solid shot may contain a pyrotechnic compound if a tracer or spotting charge is used...

 fired by these weapons are usually fitted with different types of fuses
Fuse (explosives)
In an explosive, pyrotechnic device or military munition, a fuse is the part of the device that initiates function. In common usage, the word fuse is used indiscriminately...

 (barometric, time-delay, or proximity
Proximity fuze
A proximity fuze is a fuze that is designed to detonate an explosive device automatically when the distance to target becomes smaller than a predetermined value or when the target passes through a given plane...

) to send exploding metal fragments into the area of the airborne target. For shorter-range work, a lighter weapon with a higher rate of fire
Rate of fire
Rate of fire is the frequency at which a specific weapon can fire or launch its projectiles. It is usually measured in rounds per minute , or per second .-Overview:...

 is required, to increase a hit probability on a fast airborne target. Weapons between 20 mm
20 mm caliber
The 20 mm caliber is a specific size of cannon or autocannon ammunition, commonly the smallest caliber which is unambiguously a cannon and not a heavy machine gun....

 and 40 mm caliber have been widely used in this role. Smaller weapons, typically .50 caliber or even 8 mm rifle caliber guns have been used in the smallest mounts.

Unlike the heavier guns, these smaller weapons are in widespread use due to their low cost and ability to quickly follow the target. Classic examples of autocannons and large caliber guns are the 40 mm autocannon
Bofors 40 mm gun
The Bofors 40 mm gun is an anti-aircraft autocannon designed by the Swedish defence firm of Bofors Defence...

 and the 8.8 cm FlaK 18, 36 gun, both designed by Bofors
Bofors
The name Bofors has been associated with the iron industry for more than 350 years.Located in Karlskoga, Sweden, the company originates from the hammer mill "Boofors" founded 1646. The modern corporate structure was created in 1873 with the foundation of Aktiebolaget Bofors-Gullspång...

 of Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

. Artillery weapons of this sort have for the most part been superseded by the effective surface-to-air missile systems that were introduced in the 1950s, although they were still retained by many nations. The development of surface-to-air missiles began in Nazi Germany
Nazi Germany
Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...

 during the late World War II with missiles such as the Wasserfall, though no working system was deployed before the war's end, and represented new attempts to increase effectiveness of the anti-aircraft systems faced with growing threat from bomber
Bomber
A bomber is a military aircraft designed to attack ground and sea targets, by dropping bombs on them, or – in recent years – by launching cruise missiles at them.-Classifications of bombers:...

s. Land-based SAMs can be deployed from fixed installations or mobile launchers, either wheeled or tracked. The tracked vehicles are usually armoured vehicles specifically designed to carry SAMs.

Larger SAMs may be deployed in fixed launchers, but can be towed/re-deployed at will. The SAMs launched by individuals are known in the United States as the Man-Portable Air Defence Systems (MANPADS). MANPADS of the former Soviet Union have been exported around the World, and can be found in use by many armed forces. Targets for non-ManPAD SAMs will usually be acquired by air-search radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

, then tracked before/while a SAM is "locked-on" and then fired. Potential targets, if they are military aircraft, will be identified as friend or foe
Identification friend or foe
In telecommunications, identification, friend or foe is an identification system designed for command and control. It is a system that enables military and national interrogation systems to identify aircraft, vehicles, or forces as friendly and to determine their bearing and range from the...

 before being engaged. The developments in the latest and relatively cheap short-range missiles have begun to replace autocannons in this role.

The interceptor aircraft (or simply interceptor) is a type of fighter aircraft
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...

 designed specifically to intercept and destroy enemy aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

, particularly bombers, usually relying on high speed and altitude capabilities. A number of jet interceptors such as the F-102 Delta Dagger
F-102 Delta Dagger
The Convair F-102 Delta Dagger was a US interceptor aircraft built as part of the backbone of the United States Air Force's air defenses in the late 1950s. Entering service in 1956, its main purpose was to intercept invading Soviet bomber fleets...

, the F-106 Delta Dart
F-106 Delta Dart
The Convair F-106 Delta Dart was the primary all-weather interceptor aircraft for the United States Air Force from the 1960s through the 1980s. Designed as the so-called "Ultimate Interceptor", it has proven to be the last dedicated interceptor in USAF service to date...

, and the MiG-25
Mikoyan-Gurevich MiG-25
The Mikoyan-Gurevich MiG-25 is a supersonic interceptor and reconnaissance aircraft that was among the fastest military aircraft to enter service. Designed by the Soviet Union's Mikoyan-Gurevich bureau the first prototype flew in 1964 with entry into service in 1970...

 were built in the period starting after the end of World War II and ending in the late 1960s, when they became less important due to the shifting of the strategic bombing
Strategic bombing
Strategic bombing is a military strategy used in a total war with the goal of defeating an enemy nation-state by destroying its economic ability and public will to wage war rather than destroying its land or naval forces...

 role to ICBMs. Invariably the type is differentiated from other fighter aircraft designs by higher speeds and shorter operating ranges, as well as much reduced ordnance payloads.

The radar systems use electromagnetic
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...

 waves to identify the range, altitude, direction, or speed of aircraft and weather formations
Weather forecasting
Weather forecasting is the application of science and technology to predict the state of the atmosphere for a given location. Human beings have attempted to predict the weather informally for millennia, and formally since the nineteenth century...

 to provide tactical and operational warning and direction, primarily during defensive operations. In their functional roles they provide target search, threat, guidance, reconnaissance,
navigation, instrumentation, and weather reporting support to combat operations.

Future developments

If current trends continue, missiles will replace gun systems completely in "first line" service. Guns are being increasingly pushed into specialist roles, such as the Dutch Goalkeeper CIWS
Goalkeeper CIWS
Goalkeeper is a Dutch close-in weapon system introduced in 1979 and in use , which primarily defends ships against incoming missiles and ballistic shells. This system consists of an autocannon and an advanced radar which in typically six seconds detects incoming fire, determines its trajectory,...

, which uses the GAU-8/A Avenger 30 mm seven-barrel Gatling Gun
Gatling gun
The Gatling gun is one of the best known early rapid-fire weapons and a forerunner of the modern machine gun. It is well known for its use by the Union forces during the American Civil War in the 1860s, which was the first time it was employed in combat...

 for last ditch anti-missile and anti-aircraft defense. Even this formerly front-line weapon is currently being replaced by new missile systems, such as the Rolling Airframe Missile, which is smaller, faster, and allows for mid-flight course correction (guidance) to ensure a hit. To bridge the gap between Guns and Missiles, Russia in particular produces the Kashtan CIWS
Kashtan CIWS
The Kashtan Close-in weapon system is a modern naval air defence gun-missile system deployed by the Russian Navy.It is found on the aircraft carrier Admiral Kuznetsov, Kirov class battlecruisers, Neustrashimy class, People's Liberation Army Navy Sovremenny class destroyers and Indian Talwar...

, which uses both guns and missiles for final defense. Two six-barreled 30 mm Gsh-6-30
Gryazev-Shipunov GSh-6-30
The Gryazev-Shipunov GSh-6-30 is a Russian 30 mm cannon used by Soviet and later CIS military aircraft.The GSh-6-30, designed in the early 1970s and entering service in 1975, is a six-barreled Gatling gun similar in design to the Gryazev-Shipunov GSh-6-23. It was based on the naval AO-18 used in...

 gatling guns and 9M311 surface to air missiles provide for its defensive capabilities.

Upsetting this development to all-missile systems is the current move to stealth aircraft
Stealth aircraft
Stealth aircraft are aircraft that use stealth technology to avoid detection by employing a combination of features to interfere with radar as well as reduce visibility in the infrared, visual, audio, and radio frequency spectrum. Development of stealth technology likely began in Germany during...

. Long range missiles depend on long-range detection to provide significant lead. Stealth designs cut detection ranges so much that the aircraft is often never even seen, and when it is, often too late for an intercept. Systems for detection and tracking of stealthy aircraft are a major problem for anti-aircraft development.

However, as Stealth technology
Stealth technology
Stealth technology also termed LO technology is a sub-discipline of military tactics and passive electronic countermeasures, which cover a range of techniques used with personnel, aircraft, ships, submarines, and missiles, to make them less visible to radar, infrared, sonar and other detection...

 grows, so does anti-stealth technology. Multiple transmitter radars such as those from Bistatic radar
Bistatic radar
Bistatic radar is the name given to a radar system which comprises a transmitter and receiver which are separated by a distance that is comparable to the expected target distance. Conversely, a radar in which the transmitter and receiver are collocated is called a monostatic radar...

s and Low-frequency radar
Low-frequency radar
Low-frequency radar uses frequencies lower than 1 GHz, as opposed to the usual radar bands, which range from 2 Ghz and up,and the maximum is 40 Ghz.The radar cross section of any target depends on the radar transmitted frequency...

s are said to have the capabilities to detect stealth aircraft. Advanced forms of Thermographic camera
Thermographic camera
A thermographic camera or infrared camera is a device that forms an image using infrared radiation, similar to a common camera that forms an image using visible light...

s such as those that incorporate QWIPs
Quantum well infrared photodetector
A quantum well infrared photodetector , is an infrared photodetector made from semiconductor materials which contain one or more quantum wells. These can be integrated together with electronics and optics to make infrared cameras for thermography. A very common well material is gallium arsenide,...

 would be able to optically see a Stealth aircraft regardless of the aircraft's RCS
Radar cross section
Radar cross section is a measure of how detectable an object is with a radar. A larger RCS indicates that an object is more easily detected.An object reflects a limited amount of radar energy...

. In addition, Side looking radars, High-powered Optical Satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

s, and sky-scanning, high-Aperature, high sensitivity Radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

s such as Radio telescope
Radio telescope
A radio telescope is a form of directional radio antenna used in radio astronomy. The same types of antennas are also used in tracking and collecting data from satellites and space probes...

s, would all be able to narrow down the location of a Stealth aircraft under certain parameters. The newest SAM's have a claimed ability to be able to detect and engage stealth targets, with the most notable being the S-400, which is claimed to be able to detect a target with a 0.05 meter squared RCS from 90 km away.

Another potential weapon system for anti-aircraft use is the laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

. Although air planners imagined lasers in combat since the late 1960s, only the most modern laser systems are currently reaching what could be considered "experimental usefulness". In particular the Tactical High Energy Laser
Tactical High Energy Laser
The Tactical High-Energy Laser, or THEL, is a laser developed for military use, also known as the Nautilus laser system. The mobile version is the Mobile Tactical High-Energy Laser, or MTHEL.- Demonstrator :...

 can be used in the anti-aircraft and anti-missile role. If current developments continue, some believe it is reasonable to suggest that lasers will play a major role in air defense starting in the next ten years.

The future of projectile based weapons may be found in the railgun
Railgun
A railgun is an entirely electrical gun that accelerates a conductive projectile along a pair of metal rails using the same principles as the homopolar motor. Railguns use two sliding or rolling contacts that permit a large electric current to pass through the projectile. This current interacts...

, currently tests are underway on developing systems that could create as much damage as a BGM-109 Tomahawk
BGM-109 Tomahawk
The Tomahawk is a long-range, all-weather, subsonic cruise missile. Introduced by General Dynamics in the 1970s, it was designed as a medium- to long-range, low-altitude missile that could be launched from a surface platform. It has been improved several times and, by way of corporate divestitures...

, but at a fraction of the cost. In February 2008 the US Navy tested a magnetic railgun; it fired a shell at 5600 miles (9,012.3 km) per hour using 10 megajoules of energy. Its expected performance is over 13000 miles (20,921.4 km) per hour muzzle velocity, accurate enough to hit a 5 meter target from 200 nautical miles (370.4 km) away while shooting at 10 shots per minute. It is expected to be ready in 2020 to 2025. These systems while currently designed for static targets would only need the ability to be retargeted to become the next generation of AA system.

Force structures

Most Western and Commonwealth militaries integrate air defence purely with the traditional services, of the military (i.e. army
Army
An army An army An army (from Latin arma "arms, weapons" via Old French armée, "armed" (feminine), in the broadest sense, is the land-based military of a nation or state. It may also include other branches of the military such as the air force via means of aviation corps...

, navy
Navy
A navy is the branch of a nation's armed forces principally designated for naval and amphibious warfare; namely, lake- or ocean-borne combat operations and related functions...

 and air force
Air force
An air force, also known in some countries as an air army, is in the broadest sense, the national military organization that primarily conducts aerial warfare. More specifically, it is the branch of a nation's armed services that is responsible for aerial warfare as distinct from an army, navy or...

), as a separate arm or as part of artillery. In the United States Army for instance, air defence is part of the artillery arm, while in the Pakistan Army, it was split off from Artillery to form a separate arm of its own in 1990. This is in contrast to some (largely communist or ex-communist) countries where not only are there provisions for air defence in the army, navy and air force but there are specific branches that deal only with the air defence of territory, for example, the Soviet PVO Strany
Soviet Anti-Air Defense
The Soviet Air Defence Forces was the air defense branch of the Soviet Armed Forces. It continued being a service branch of the Armed Forces of the Russian Federation from 1991 to 1998. Unlike Western air defense forces, V-PVO was a branch of the military unto itself, separate from the Soviet...

. The USSR also had a separate strategic rocket force in charge of nuclear ICBMs.

Navy

Smaller boats and ships typically have machine-guns or fast cannons, which can often be deadly to low-flying aircraft if linked to a radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

-directed fire-control system
Fire-control system
A fire-control system is a number of components working together, usually a gun data computer, a director, and radar, which is designed to assist a weapon system in hitting its target. It performs the same task as a human gunner firing a weapon, but attempts to do so faster and more...

 radar-controlled cannon
Close-in weapon system
A close-in weapon system , often pronounced sea-whiz, is a naval shipboard point-defense weapon for detecting and destroying at short range incoming anti-ship missiles and enemy aircraft which have penetrated the outer defenses....

 for point defence. Some vessels like Aegis
Aegis combat system
The Aegis Combat System is an integrated naval weapons system developed by the Missile and Surface Radar Division of RCA, and now produced by Lockheed Martin...

 cruisers are as much a threat to aircraft as any land-based air defence system. In general, naval vessels should be treated with respect by aircraft, however the reverse is equally true. Carrier battle group
Carrier battle group
A carrier battle group consists of an aircraft carrier and its escorts, together composing the group. The first naval task forces built around carriers appeared just prior to and during World War II. The Imperial Japanese Navy was the first to assemble a large number of carriers into a single...

s are especially well defended, as not only do they typically consist of many vessels with heavy air defence armament but they are also able to launch fighter jets for combat air patrol
Combat air patrol
Combat air patrol is a type of flying mission for fighter aircraft.A combat air patrol is an aircraft patrol provided over an objective area, over the force protected, over the critical area of a combat zone, or over an air defense area, for the purpose of intercepting and destroying hostile...

 overhead to intercept incoming airborne threats.

Some modern submarines, such as the Type 212 submarine
Type 212 submarine
The German Type 212 class, also Italian Todaro class, is a highly advanced design of non-nuclear submarine developed by Howaldtswerke-Deutsche Werft AG and Fincantieri S.p.a. for the German and Italian Navy. It features diesel propulsion and an additional air-independent propulsion system using...

s of the German Navy
German Navy
The German Navy is the navy of Germany and is part of the unified Bundeswehr .The German Navy traces its roots back to the Imperial Fleet of the revolutionary era of 1848 – 52 and more directly to the Prussian Navy, which later evolved into the Northern German Federal Navy...

, are equipped with surface-to-air missile systems, since helicopters and anti-submarine warfare
Anti-submarine warfare
Anti-submarine warfare is a branch of naval warfare that uses surface warships, aircraft, or other submarines to find, track and deter, damage or destroy enemy submarines....

 aircraft are significant threats.

Army

Armies typically have air defence in depth, from integral MANPADS like RBS 70
RBS 70
RBS 70 is a man-portable air-defense system designed for anti-aircraft warfare in all climate zones and with little to no support from other forces. Originally designed and manufactured by the Swedish defence firm of Bofors Defence...

, Stinger
FIM-92 Stinger
The FIM-92 Stinger is a personal portable infrared homing surface-to-air missile , which can be adapted to fire from ground vehicles and helicopters , developed in the United States and entered into service in 1981. Used by the militaries of the U.S...

 and Igla at smaller force levels up to army-level missile defence systems such as Angara and Patriot
MIM-104 Patriot
The MIM-104 Patriot is a surface-to-air missile system, the primary of its kind used by the United States Army and several allied nations. It is manufactured by the Raytheon Company of the United States. The Patriot System replaced the Nike Hercules system as the U.S. Army's primary High to Medium...

. Often, the high-altitude long-range missile systems force aircraft to fly at low level, where anti-aircraft guns can bring them down. As well as the small and large systems, for effective air defence there must be intermediate systems. These may be deployed at regiment-level and consist of platoons of self-propelled anti-aircraft platforms, whether they are self-propelled anti-aircraft guns (SPAAGs), integrated air-defence systems like Tunguska or all-in-one surface-to-air missile platforms like Roland or SA-8 Gecko.

Air force

Air defense by air forces is typically taken care of by fighter jets carrying air-to-air missile
Air-to-air missile
An air-to-air missile is a missile fired from an aircraft for the purpose of destroying another aircraft. AAMs are typically powered by one or more rocket motors, usually solid fuelled but sometimes liquid fuelled...

s. However, most air forces choose to augment airbase defense with surface-to-air missile
Surface-to-air missile
A surface-to-air missile or ground-to-air missile is a missile designed to be launched from the ground to destroy aircraft or other missiles...

 systems as they are such valuable targets and subject to attack by enemy aircraft. In addition, countries without dedicated air defense forces often relegate these duties to the air force. For example, the United States' strategic air defense is the domain of the Air Force, even when it is performed by missiles launched from fixed installations. For example, see Project Nike
Project Nike
Project Nike was a U.S. Army project, proposed in May 1945 by Bell Laboratories, to develop a line-of-sight anti-aircraft missile system. The project delivered the United States' first operational anti-aircraft missile system, the Nike Ajax, in 1953...

.

Area air defense

Area air defence, the air defense of a specific area or location, (as opposed to point defense), have historically been operated by both armies (Anti-Aircraft Command
Anti-Aircraft Command
Anti-Aircraft Command was a British Army command of the Second World War that controlled the anti-aircraft artillery units of the British Isles.-History:...

 in the British Army, for instance) and Air Forces (the USAF's Nike Hercules and its sibling programmes). Area defence systems have medium to long range and can be made up of various other systems and networked into an area defence system (in which case it may be made up of several short range systems combined to effectively cover an area). An example of area defence is the defence of Saudi Arabia and Israel by MIM-104 Patriot
MIM-104 Patriot
The MIM-104 Patriot is a surface-to-air missile system, the primary of its kind used by the United States Army and several allied nations. It is manufactured by the Raytheon Company of the United States. The Patriot System replaced the Nike Hercules system as the U.S. Army's primary High to Medium...

 missile batteries during the first Gulf War
Gulf War
The Persian Gulf War , commonly referred to as simply the Gulf War, was a war waged by a U.N.-authorized coalition force from 34 nations led by the United States, against Iraq in response to Iraq's invasion and annexation of Kuwait.The war is also known under other names, such as the First Gulf...

, where the objective was to cover populated areas.

Mobility

Most modern air defence systems are fairly mobile. Even the larger systems tend to be mounted on trailers and are designed to be fairly quickly broken down or set up. In the past, this was not always the case. Early missile systems were cumbersome and required much infrastructure; many could not be moved at all. With the diversification of air defence there has been much more emphasis on mobility. Most modern systems are usually either self-propelled (i.e. guns or missiles are mounted on a truck or tracked chassis) or easily towed. Even systems that consist of many components (transporter/erector/launchers
Transporter erector launcher
A transporter erector launcher is a vehicle with an integrated prime mover that can carry, elevate to firing position and launch one or more missiles. Such vehicles exist for both surface-to-air missiles and surface-to-surface missiles...

, radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

s, command posts etc.) benefit from being mounted on a fleet of vehicles. In general, a fixed system can be identified, attacked and destroyed whereas a mobile system can show up in places where it is not expected. Soviet systems especially concentrate on mobility, after the lessons learnt in the Vietnam war
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...

 between the USA and Vietnam. For more information on this part of the conflict, see SA-2 Guideline.

North Korea
North Korea
The Democratic People’s Republic of Korea , , is a country in East Asia, occupying the northern half of the Korean Peninsula. Its capital and largest city is Pyongyang. The Korean Demilitarized Zone serves as the buffer zone between North Korea and South Korea...

 (officially the DPRK) has inherited a lot of older Soviet equipment. One major reason for the success of the U.N.
United Nations
The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...

 forces during the Korean War
Korean War
The Korean War was a conventional war between South Korea, supported by the United Nations, and North Korea, supported by the People's Republic of China , with military material aid from the Soviet Union...

 (1950–1953) against the Korea was the air superiority they were able to attain. As tensions still exist on the Korean Peninsula and Korea is so heavily militarised, their air-defence network is amongst the strongest of a non-superpower. A large part of it consists of a number of older, fixed systems like SA-2, SA-3, and SA-5, but DPRK is also in possession of many mobile systems that have proven deadly in the past.

Air defence versus air defence suppression

The U.S. Air Force, in conjunction with the members of NATO, has developed significant tactics for air defence suppression. Dedicated weapons such as anti-radiation missile
Anti-radiation missile
An anti-radiation missile is a missile which is designed to detect and home on an enemy radio emission source. Typically these are designed for use against an enemy radar, although jammers and even radios used for communication can also be targeted in this manner.- Air-to-Ground :Most ARM designs...

s and advanced electronics intelligence and electronic countermeasures
Electronic countermeasures
An electronic countermeasure is an electrical or electronic device designed to trick or deceive radar, sonar or other detection systems, like infrared or lasers. It may be used both offensively and defensively to deny targeting information to an enemy...

 platforms seek to suppress or negate the effectiveness of an opposing air-defence system. It is an arms race; as better jamming, countermeasures and anti-radiation weapons are developed, so are better SAM systems with ECCM
Electronic counter-countermeasures
Electronic counter-countermeasures is a part of electronic warfare which includes a variety of practices which attempt to reduce or eliminate the effect of electronic countermeasures on electronic sensors aboard vehicles, ships and aircraft and weapons such as missiles. ECCM is also known as...

 capabilities and the ability to shoot down anti-radiation missiles and other munitions aimed at them or the targets they are defending.

See also

  • Artillery
    Artillery
    Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

  • Gun laying
    Gun laying
    Gun laying is the process of aiming an artillery piece, such as a gun, howitzer or mortar on land or at sea against surface or air targets. It may be laying for direct fire, where the gun is aimed similarly to a rifle, or indirect fire, where firing data is calculated and applied to the sights...

  • List of anti-aircraft weapons
  • Self-propelled anti-aircraft weapon
    Self-propelled anti-aircraft weapon
    An anti-aircraft vehicle, also known as a self-propelled anti-aircraft weapon or self-propelled air defense system , is a mobile vehicle with a dedicated anti-aircraft capability...


External links

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