An underground hangar complex may include tunnels containing the normal elements of a military air base - fuel storage, weapon storage, rooms for maintaining the aircraft systems, a communications centre, briefing rooms, kitchen, dining rooms, sleeping areas and generators for electrical power.
Countries that have used underground hangars include Albania, China, India, Pakistan, Italy, North Korea, Norway, South Africa, Sweden, Switzerland, Taiwan, Vietnam and Yugoslavia.
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In 1941 the Swedish Air Force began building its first underground hangar at Göta Air Force Wing (F 9), located near Gothenburg in south-west Sweden, it was commissioned in 1943. After World War II plans were made up for building underground hangars at every air force base that had suitable rock conditions. These ambitious building plans proved to be too expensive and were reduced to hangars at certain selected air bases. A second underground hangar was built in 1947 at Södertörn Air Force Wing (F 18) which began operating in 1950. After that plans were finalized for building underground hangars capable of surviving close hits by tactical nuclear weapons. This required that these new hangars be much deeper, with 25 to 30 meters of rock cover, and heavy-duty blast doors in concrete. The Saab 37 Viggen aircraft was designed with a folding tail fin to fit into low hangars. The Aeroseum an aircraft museum open to the public in Gothenburg is housed in the larger cold war era Underground Hangar at Säve.
Six Flugzeugkaverne (aircraft caverns), each with space for 30 or more aircraft, were constructed for the Swiss Air Force. One at Meiringen Air Base has been expanded to operate F/A-18 Hornet aircraft. Originally, the plan for the aircraft cavern started its life as a design as a cavern-like aircraft hangar (German "Kavernenflugplatz") with the possibility launch combat aircraft from the mountain air base. High costs and technical difficulties prevented these from realisation The idea of using roads as runways was later part of the design demands for the Swiss motorway network.
The only Taiwanese airbase with underground hangars is Jiashan Airbase, located in Hualien on the east coast of Taiwan, to guard against a massive missile strike launched from China. Underground hangars in Jiashan Airbase have deployed F-16 A/B and F-5 E-F squadrons.
The largest underground hangar complex in former Yugoslavia was at Željava Airport near Bihać, with enough space for 80 MiG-21s. Slatina Air Base, located at Pristina International Airport, contained the second largest.
- F/A-18 inside cavern Meiringen AFB
- "Archived copy" (PDF). Archived from the original (PDF) on 2012-07-22. Retrieved 2012-07-22.CS1 maint: Archived copy as title (link) Historic Buildings of the Swiss Air Force (German)
- Reduit und Schweizer Bunkerprojekte 1995
- (in German) Flugplätze stehen unter Schutz bernerzeitung.ch
- (in German) FLUGPLATZKOMMANDO MEIRINGEN
|Wikimedia Commons has media related to Underground hangars.|
-  Armeeschulfilm über die Schweizer Flugzeugkaverne
- "Underground Hangars to Protect War Planes" Popular Mechanics, September 1937
|M113 in Cavern Turtmann|
|F-5E in Cavern|
|Hawker Hunter in Cavern|
|Patrouille Suisse F-5E in Cavern|
|F/A-18 and F-5 Cavern Meiringen|