Hardened Aircraft Shelter
Encyclopedia
Hardened Aircraft Shelters (HAS), or Protective Aircraft Shelter (PAS), are a reinforced structure to house and protect military aircraft
from enemy attack. Cost considerations and building practicalities limit their use to fighter
size aircraft.
s) which aim to prevent or at least degrade enemy attacks. The widespread adoption of Hardened Aircraft Shelters can be traced back to lessons learned in the 1967 Arab-Israeli Six-Day War
when the Israeli Air Force
decimated the unprotected Egyptian Air Force
, at the time the largest and most advanced air force in the Arab world, at its airbase
s.
As with many military items, whether structures, tank
s or aircraft, its most prolific use was during the Cold War
. NATO and Warsaw Pact
countries built hundreds of HAS's across Europe
. In this context Hardened Aircraft Shelters were built to protect aircraft from conventional attacks as well as nuclear
, chemical
and biological
strikes. NATO shelters, built to standard designs across the continent, were designed to withstand a direct hit by a 500lb (226 kg) bomb, or a near miss by a larger one (i.e., 1,000 lb+). In theory HAS's were also built to protect aircraft in a nuclear strike; however, the effect of such an attack on airfield taxiway
s, runway
s, support facilities and personnel would have made any retaliatory mission extremely difficult and subsequent return and rearming almost impossible.
In the post-cold war era the value of the HAS concept was further eroded by the introduction of precision-guided munition
s. Iraq
's HAS hangars were built to a standard somewhat higher than NATO or Warsaw Pact shelters, but nevertheless proved almost useless during the Gulf War
. Early attempts to defeat them typically used a "one-two punch" using a TV guided
missile to blast open the doors, followed by bombs tossed in the front. US efforts soon turned to simply dropping a 2,000 lb laser guided bomb on the top, which would easily penetrate the roof and explode within. Although NATO hangar
s would remain useful against any conceivable attack on Europe in the short term (which would generally lack precision guidance systems), the value of HAS hangars against well-equipped first world air forces is effectively zero.
Kevlar
lined deployable shelters could protect aircraft from bomblets (a common anti-airfield weapon). However this would provide no protection from PGMs.
Wider dispersal (distance between aircraft) at airfields would decrease the vulnerability of aircraft. This would also force an enemy to increase the number of attacking aircraft greatly, or spend more time over the target. Either way the effect of airfield defences would take a heavy toll on the aggressor. However like HAS, dispersal can be expensive, requiring massive construction of hardstanding. Defense against enemy special force
s is also more difficult.
Dispersing aircraft between many bases greatly increases the cost of attacking a given number of aircraft, as measured by the number of attack aircraft required. However, this option similarly increases the defenders' cost of operation and degrades their efficiency.
Several air forces have used tunnels dug into a mountainside as underground hangar
s.
Military aircraft
A military aircraft is any fixed-wing or rotary-wing aircraft that is operated by a legal or insurrectionary armed service of any type. Military aircraft can be either combat or non-combat:...
from enemy attack. Cost considerations and building practicalities limit their use to fighter
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...
size aircraft.
Background
HAS's are a passive defence measure, i.e., they limit the effect of an attack, as opposed to active defences (e.g., surface-to-air missileSurface-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...
s) which aim to prevent or at least degrade enemy attacks. The widespread adoption of Hardened Aircraft Shelters can be traced back to lessons learned in the 1967 Arab-Israeli Six-Day War
Six-Day War
The Six-Day War , also known as the June War, 1967 Arab-Israeli War, or Third Arab-Israeli War, was fought between June 5 and 10, 1967, by Israel and the neighboring states of Egypt , Jordan, and Syria...
when the Israeli Air Force
Israeli Air Force
The Israeli Air Force is the air force of the State of Israel and the aerial arm of the Israel Defense Forces. It was founded on May 28, 1948, shortly after the Israeli Declaration of Independence...
decimated the unprotected Egyptian Air Force
Egyptian Air Force
The Egyptian Air Force, or EAF , is the aviation branch of the Egyptian Armed Forces. The EAF is headed by an Air Marshal . Currently, the commander of the Egyptian Air Force is Air Marshal Reda Mahmoud Hafez Mohamed...
, at the time the largest and most advanced air force in the Arab world, at its airbase
Airbase
An airbase is a military airfield that provides basing and support of military aircraft....
s.
As with many military items, whether structures, tank
Tank
A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...
s or aircraft, its most prolific use was during 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...
. NATO and Warsaw Pact
Warsaw Pact
The Warsaw Treaty Organization of Friendship, Cooperation, and Mutual Assistance , or more commonly referred to as the Warsaw Pact, was a mutual defense treaty subscribed to by eight communist states in Eastern Europe...
countries built hundreds of HAS's across Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
. In this context Hardened Aircraft Shelters were built to protect aircraft from conventional attacks as well as nuclear
Nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...
, chemical
Chemical warfare
Chemical warfare involves using the toxic properties of chemical substances as weapons. This type of warfare is distinct from Nuclear warfare and Biological warfare, which together make up NBC, the military acronym for Nuclear, Biological, and Chemical...
and biological
Biological warfare
Biological warfare is the use of biological toxins or infectious agents such as bacteria, viruses, and fungi with intent to kill or incapacitate humans, animals or plants as an act of war...
strikes. NATO shelters, built to standard designs across the continent, were designed to withstand a direct hit by a 500lb (226 kg) bomb, or a near miss by a larger one (i.e., 1,000 lb+). In theory HAS's were also built to protect aircraft in a nuclear strike; however, the effect of such an attack on airfield taxiway
Taxiway
A taxiway is a path on an airport connecting runways with ramps, hangars, terminals and other facilities. They mostly have hard surface such as asphalt or concrete, although smaller airports sometimes use gravel or grass....
s, runway
Runway
According to ICAO a runway is a "defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft." Runways may be a man-made surface or a natural surface .- Orientation and dimensions :Runways are named by a number between 01 and 36, which is generally one tenth...
s, support facilities and personnel would have made any retaliatory mission extremely difficult and subsequent return and rearming almost impossible.
In the post-cold war era the value of the HAS concept was further eroded by the introduction of precision-guided munition
Precision-guided munition
A precision-guided munition is a guided munition intended to precisely hit a specific target, and to minimize damage to things other than the target....
s. Iraq
Iraq
Iraq ; officially the Republic of Iraq is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert....
's HAS hangars were built to a standard somewhat higher than NATO or Warsaw Pact shelters, but nevertheless proved almost useless during the 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...
. Early attempts to defeat them typically used a "one-two punch" using a TV guided
Precision-guided munition
A precision-guided munition is a guided munition intended to precisely hit a specific target, and to minimize damage to things other than the target....
missile to blast open the doors, followed by bombs tossed in the front. US efforts soon turned to simply dropping a 2,000 lb laser guided bomb on the top, which would easily penetrate the roof and explode within. Although NATO hangar
Hangar
A hangar is a closed structure to hold aircraft or spacecraft in protective storage. Most hangars are built of metal, but other materials such as wood and concrete are also sometimes used...
s would remain useful against any conceivable attack on Europe in the short term (which would generally lack precision guidance systems), the value of HAS hangars against well-equipped first world air forces is effectively zero.
Advantages
- Reduces vulnerability of aircraft to all but the most accurate precision weaponry
- Combined with active airfield defences increases survivability of defender's aircraft and cost to enemy's forces.
- An alternative option, dispersal of aircraft to many different bases, reduces the efficiency of aircraft at both squadronSquadron (aviation)A squadron in air force, army aviation or naval aviation is mainly a unit comprising a number of military aircraft, usually of the same type, typically with 12 to 24 aircraft, sometimes divided into three or four flights, depending on aircraft type and air force...
and Air Force level. - Nuclear weaponNuclear weaponA nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...
s can be stored in the HAS near the aircraft, in a vault, e.g., the United States Air ForceUnited States Air ForceThe 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...
Weapon Storage and Security System (WS3).
Disadvantages
- Hardened shelters are expensive.
- Hardened shelters are usually too small to easily accommodate large aircraft such as strategic transport aircraft and large surveillance aircraftSurveillance aircraftA surveillance aircraft is an aircraft used for surveillance — collecting information over time. They are operated by military forces and other government agencies in roles such as intelligence gathering, battlefield surveillance, airspace surveillance, observation , border patrol and fishery...
. - Time taken for construction requires forward planning regarding most likely combat zones. If a conflict flares up quickly aircraft may be afforded no protection, e.g. in both the Gulf WarGulf WarThe 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...
and 2003 Iraq War many coalition aircraft had only sun shelters, not hardened facilities. - When first developed, the likelihood of a direct hit was minimal. Today, with Precision-guided munitionPrecision-guided munitionA precision-guided munition is a guided munition intended to precisely hit a specific target, and to minimize damage to things other than the target....
s (PGMs) and adequate training, delivering a direct hit on a HAS is trivial. Coalition aircraft destroyed over half of Iraq's HASs during the Gulf War. - GermanyGermanyGermany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
's LuftwaffeLuftwaffeLuftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....
has conducted tests to establish the effect of humidity inside a shelter on its aircraft's avionics. Results suggested the higher relative humidity has a higher corrosive effect than outside its shelters. Supply of dry air to avionics compartments has decreased corrosion and increased serviceability.
Alternatives
- Deployable shelters
Kevlar
Kevlar
Kevlar is the registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora. Developed at DuPont in 1965, this high strength material was first commercially used in the early 1970s as a replacement for steel in racing tires...
lined deployable shelters could protect aircraft from bomblets (a common anti-airfield weapon). However this would provide no protection from PGMs.
- Dispersal at bases
Wider dispersal (distance between aircraft) at airfields would decrease the vulnerability of aircraft. This would also force an enemy to increase the number of attacking aircraft greatly, or spend more time over the target. Either way the effect of airfield defences would take a heavy toll on the aggressor. However like HAS, dispersal can be expensive, requiring massive construction of hardstanding. Defense against enemy special force
Special Force
Special Force is a first-person shooter military video game, published by Hezbollah, created using the Genesis 3D engine. The game is set in a 3D environment, in which the player takes the role of a Hezbollah combatant fighting the IDF...
s is also more difficult.
- Dispersal between bases
Dispersing aircraft between many bases greatly increases the cost of attacking a given number of aircraft, as measured by the number of attack aircraft required. However, this option similarly increases the defenders' cost of operation and degrades their efficiency.
- Underground hangars
Several air forces have used tunnels dug into a mountainside as underground hangar
Underground hangar
An Underground hangar is a type of hangar for military aircraft, usually dug into the side of a mountain for protection. It is bigger and more protected than a Hardened Aircraft Shelter ....
s.