The first aboveground hardened shelters were built by the United States Marine Corps (USMC) at Ewa Field, Oahu, beginning in September 1942. Made of reinforced concrete and covered with soil and plants, the shelters offered excellent protection from anything other than a direct bomb hit or head-on strafing run. Because of their clamshell design, the width and length shrinks as one moves up the side of the shelter, and height drops as one moves toward the rear. Thus this design would not be appropriate for larger aircraft with tricycle landing gear, but the design was fine for USMC tail-dragging aircraft, such as the Grumman F6F Hellcat, Grumman F4F Wildcat, and Vought F4U Corsair fighters. These shelters measured 18 feet high and 55 feet wide (floor level) in front and 39 feet deep. Concrete facing was roughly 3 feet high with 12 to 18 inches of concrete protection overall.
Initially tied to the war in Vietnam, various elements of the Air Staff, including the Directorate of Civil Engineering, began formal studies by mid-1962 “relative to protection of fighter-type aircraft on overseas bases”. As the program matured, the usefulness of a hardened aircraft shelter became obvious to North Atlantic Treaty Organization (NATO) and the first field studies were conducted at Bitburg, Germany. The U.S. Army Corps of Engineers Mediterranean Division begun taking steps as part of the Theater Air Base Vulnerability Evaluation Exercise (TAB VEE), program. Stemming from this program, Army engineers designed and constructed aircraft shelters that used reinforced concrete poured over liners made of corrugated-steel arches. In early 1969, the Mediterranean Division received authorization to design and build maintenance and parking hangers for the Air Force at Aviano in Italy and Incirlik in Turkey. Paralleling TAB VEE, the Air Force inaugurated a program refined specifically for Vietnam entitled Concrete Sky. The result of these effort produced first and second generation Protective Aircraft Shelters (PAS) to shield aircraft from conventional weapons as well as indirect nuclear attack and resulting overpressures.
As of 1974-1976, all efforts turned toward true hardening. A third generation program, DISTANT RUNNER, was underway simultaneously with upgrading TAB VEE first-generation shelters at bases all over the world. DISTANT RUNNER involved multiple classified tests on the Utah Test & Training Range (UTTR) and at several locations in New Mexico.
In 1976 a Sandia National Laboratory study to determine the best way to safeguard U.S. Air Force nuclear weapons deployed abroad led to the establishment of the Weapon Storage and Security System (WS3) program that would later be tested as part of the DISTANT RUNNER program. As this hardened storage system would mature, the newly formed Defense Nuclear Agency (DNA) would work with NATO on the PACOM Tactical Nuclear Force improvement program which was implemented in the early 1980s to begin upgrading the security of nuclear weapons.
After members of DNA were appointed as permanent members of the NATO High Level Group, which dealt with Theater Nuclear Forces, they pushed for the formation, and to lead, the Senior Level Weapons Protection Group (SLWPG) to address the security and survivability of nuclear weapons deployed to NATO countries. The DNA Deputy Director for Operations headed the U.S. delegation to the new group, which was instrumental in the installation of WS3 throughout NATO.
Part of WS3, is the Weapon Storage Vault (WSV), this is an underground vault located in the floor of a hardened aircraft shelter. A WSV holds up to four weapons and provides ballistic protection in the lowered position through its hardened lid and reinforced sidewalls. The United States calls the entire system the Weapon Storage and Security System (WS3), whereas NATO refers to it as the Weapons Security and Survivable System (WS3) . The first of these vaults were completed in Buchel Air Base, Germany in August of 1990 and would continue across various NATO airbases until 1998.
USAFE TAB VEE; 24-feet radius semicircular arch, 48 feet wide by 100.8 feet long, front closure prow shaped, vertically hinged, recessed door.
First Generation Aircraft Shelter (TAB VEE Modified); 24-feet radius semicircular arch, 48 feet wide by 100.8 feet long, front closure prow shaped, laterally opening, external flush door.
Second Generation Aircraft Shelter; 29.4-feet double-radius, pseudo-elliptical arch, 82 feet wide by 124 feet long, vertical reinforced concrete panel, laterally opening, sliding, external flush door.
Third Generation Aircraft Shelter; 27.4-feet double-radius, pseudo-elliptical arch, 70.8 feet wide by 120 feet long, vertical reinforced concrete panel, laterally opening, sliding, external flush door. Personnel door at one side with barricade.
Korean TAB VEE; 24-feet radius semicircular arch, 48 feet wide by 100.8 feet long, open front. Exhaust port in rear wall protected only by a blast deflector barricade (otherwise identical to USAFE TAB VEE). When hardened doors are installed, consider these shelters as TAB VEE Modified.
Korean Flow-Through; Constructed from third generation drawing but omits front door, back wall, and personnel door, 70.8 feet wide by 120 feet long, 27.4-feet double-radius, pseudo-elliptical arch.