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Hardened aircraft shelter at RAF Bruggen, 1981

A hardened aircraft shelters (HAS) or protective aircraft shelter (PAS) is a reinforced hangar to house and protect military aircraft from enemy attack. Cost considerations and building practicalities limit their use to fighter size aircraft.


HASs are a passive defence measure (i.e., they limit the effect of an attack, as opposed to active defences; e.g., surface-to-air missiles) which aim to prevent or at least degrade enemy attacks. The widespread adoption of hardened aircraft shelters can be traced back to lessons learned from Operation Focus; in the 1967 Arab-Israeli Six-Day War when the Israeli Air Force destroyed the unprotected Egyptian Air Force, at the time the largest and most advanced air force in the Arab world, at its airbases.

An F-16 being towed into a HAS at Volkel Air Base

As with many military items, whether structures, tanks or aircraft, its most prolific use was during the Cold War. NATO and Warsaw Pact countries built hundreds of HASs 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 500 lb (226 kg) bomb, or a near miss by a larger one (i.e., 1,000 lb+). In theory HASs were also built to protect aircraft in a nuclear strike; however, the effect of such an attack on airfield taxiways, runways, 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 munitions. 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 hangars 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.[citation needed]


Inside a PAS, showing a Weapons Storage and Security System vault in raised position holding a B61 nuclear bomb
  • 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 squadron and air force level.
  • Nuclear weapons can be stored in the HAS near the aircraft, in a vault; e.g., the United States Air Force Weapons Storage and Security System (WS3).


Two reinforced hangars showing the effects of Coalition bombing during Operation Desert Storm, 1991. These Kuwaiti shelters were built by the French and used by Iraqi forces during the conflict. Picture is of Ahmed Al Jaber Air Base - Kuwait.
  • They are in a fixed known position.
  • Hardened shelters are expensive.
  • Hardened shelters are usually too small to easily accommodate large aircraft such as strategic transport aircraft and large surveillance aircraft.
  • 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 War 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 munitions (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.
  • The German Air Force 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.[citation needed]


Deployable shelters
Kevlar 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 forces 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.
Dispersal to highway strips
Dispersal of aircraft to highway strips will present the attacker with a multitude of targets which cannot be simultaneously attacked. Survivability is enhanced if the defender also chooses to use mobile tactics, using each highway strip for a limited number of sorties before moving on to another. With penny packets of two to four aircraft at each location, such a tactic increases the difficulty of effective co-ordination, and command and control, it also increases vulnerability to attack from the ground. However with adequate planning these are not insurmountable problems; for example Sweden, one of the main subscribers to the highway strip doctrine, has a special forces unit, the Flygbasjägare, raised especially to counter the threat of attack by enemy special forces.
Underground hangars
Several air forces have used tunnels dug into a mountainside as underground hangars.

See also[edit]

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Hardened_aircraft_shelter — Please support Wikipedia.
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23 news items


Tue, 31 Mar 2015 14:44:52 -0700

A crew chief from the 52nd Aircraft Maintenance Squadron marshals an F-16 Fighting Falcon out of a hardened aircraft shelter in support of Joint Task Force Odyssey Dawn (JTF OD) on March 18, 2011.


Fri, 16 Jan 2015 04:23:02 -0800

But as Kshesh is littered with around sixty plane wrecks, it is highly unlikely the SyAAF ever managed to find or hit the aircaft, which spend most of their time hidden in a Hardened Aircraft Shelter anyway. While the presence of two operational L-39s ...

IHS Jane's 360

IHS Jane's 360
Wed, 29 Oct 2014 13:15:00 -0700

A B61 bomb is shown here, next to an F-16 fighter, inside a US Air Force Europe hardened aircraft shelter. (USAF). The United States has begun work to upgrade the B61 gravity bomb family under a life extension programme for the ageing nuclear weapon.

World Tribune

World Tribune
Thu, 20 Nov 2014 10:45:00 -0800

Officers said the base would also contain hardened aircraft shelter to withstand an enemy attack. Israel has ordered 19 F-35As in a deal estimated at $2.7 million. The air force has sought to acquire another 31 fifth-generation fighter-jets from ...
Flightglobal (blog)
Thu, 18 Dec 2014 03:35:14 -0800

The Israeli airforce (IAF) is getting ready to receive the F-35 stealth fighter. The first delivery is expected in 2017 but preparations are already in a high gear. At the Nevatim Airbase, construction of the F-35 (Adir) integrated training centre has ...
Council on Foreign Relations
Mon, 29 Sep 2014 19:49:05 -0700

We haven't built a hardened aircraft shelter in thirty years. We're doing that more. We're starting to operationally disperse our Air Forces. We're operationally dispersing our Marine forces. We are sending more naval forces to theater for littoral ...
Wired (blog)
Wed, 12 Sep 2012 12:30:00 -0700

A Predator drone waits in a hardened aircraft shelter in Iraq between missions during the now-ended Iraq war. Photo: U.S. Air Force. Spencer Ackerman Security; 09.12.12; 3:24 pm. U.S. Drones Never Left Libya; Will Hunt Benghazi Thugs. A Predator drone ...

Daily Mail

Daily Mail
Thu, 06 Jun 2013 13:28:35 -0700

Behind the scenes: A Typhoon FGR4 on display in a hardened aircraft shelter with its weapons. The plane has a top speed of 1,320mph. Enlarge. Cross-section: This detailed diagram shows the inner workings of the Typhoon aircraft - which is being ...

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