The first tier is underground in a former gypsumquarry beneath the Forest of Montmorency. The facility comprised the hardened command facility for the French Air Force.
The second tier is on the surface, and provided support services for the underground command center.
The third tier is at the top of the hill, with facilities for secure military communications.
There were no aviation facilities apart from a heliport.
Description
The base is located on the flank of the heights of the community of Taverny, with the hardened facility between 70 and 80 meters below the surface in the former quarries. The tunnels are large enough for trucks to enter. The underground climate is described as warm and dry, but the tunnels require monitoring for water penetration and dissolution of the gypsum. Somewhat more than 1000 personnel are employed at the base. The facility is provided with backup power and an independent water supply. A 2000m² Faraday Cage was completed in 1993 after six years of construction - one of the largest in Europe.
History
1815: First commercial exploitation as a gypsum quarry.
1941-1944: During World War II, the Germans converted some of these tunnels for industrial use. The SKF ball bearing factory was moved there from south of Paris. At the time of the Allied invasion, the manufacture of ball bearings had been started. The two main tunnels were connected and an entrance structure with gates was constructed. Before their evacuation of Paris, the Germans destroyed the equipment in the tunnels. Several places in the area of the plant show evidence of fire. According to a villager, the Germans used oil fires to destroy the equipment. This caused cracking and falling rocks. Mines and booby traps were left behind in the tunnels and the nearby woods; these were removed, along with the remains of the plant, by the U.S. Army. There is no evidence that the Allies bombed the tunnels during the occupation.
1946: The French Air Force used the quarry as a depot.
1961: The creation of the Territorial Air Defense Staff and the Air Force Air Defense Command. These organizations were dissolved in 1994 and replaced with the Air Defense and Air Operations Command and its Air Operations Center.
1963: Creation of BA921, attached to the 2nd Air Region, and the installation on the surface of the Strategic Air Forces Command.
1967: Installation of the Strategic Forces Operations Center underground.
1988: BA921 takes the name "Frères Mahé" in homage to three brothers killed in the command of their aircraft.
2007: The Air Operations Center moves to BA942 at Lyon Mont-Verdun. At the same time, the Air Defense and Air Operations moves to BA117 in Paris and the Air Information Center moves to BA128 at Metz.
2011: BA 921 is disestablished on 5 July 2011.
Nuclear deterrent
Taverny provided information to the following organizations:
The commander of the strategic air forces, which constitute one leg of France's nuclear deterrent.
The Analysis and Simulation Center for the Preparation of Air Operations.
