Hardened Aircraft Shelter

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.

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.

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