The aircraft-warning service for Germany and for the important occupied areas is the responsibility of the German Air Force, and is a definite integral part of the organization of defense against hostile aircraft. Although a part of the Air Signal Service, for all practical purposes the aircraft-warning service is a separate organization created for the sole purpose of constant observation of the air space over Germany, and for the prompt recognition and reporting of airplanes flying over Germany and other defended zones of the interior. This service is operated through the air district headquarters commanders, to whom the aircraft-warning service is subordinated.
In the operation of this system, there is a fixed "German territorial aircraft-warning service," as well as a mobile aircraft-warning service which is carried out by "aircraft-warning-service companies."
The fixed "aircraft-warning-service net" is mesh-like in character. The distances of individual air guard lines from one another vary between 20 and 45 miles, these distances and lines being established in accordance with tactical considerations. "Air guard stations" comprising observation and reporting stations are generally 6 to 8 miles apart. "Air guard headquarters," comprising plotting and relaying stations, are agencies of the aircraft-warning service. As with our system, the function of the air guard stations is to report the number, type, height, flying direction, identity, etc., of any planes flying over the sector. These reports find their way to a center where they are filtered and evaluated, with subsequent disposition of appropriate information to military authorities as well as to civil protection authorities.
The motorized aircraft-warning companies supplement and increase the density of the fixed aircraft-warning net, as well as being put around a temporarily vulnerable area. Although ordinarily used well forward, they may be employed on open flanks and in rear areas.
The reports of the territorial aircraft-warning service are made by telephone and wire, whereas the reports of the motorized aircraft-warning companies are made by radio.
c. Flak Intelligence Service
The aircraft-warning service is supplemented by the troop-warning service of the German AA artillery, which is similar to the U.S. Antiaircraft Artillery Information Service (AAAIS). Every active German AA unit observes the air in the area under its jurisdiction with specially trained personnel. In addition, all troop units use their own air guards to avoid surprise. The guard gives warning by means of calls, horns, sirens, or blinker lamps.
d. Use of Radio-Detection Devices
It is known that both long- and short-range radio-location instruments are now being used for warning purposes. The long-range instruments are located at intervals along the Western European coast for early warning purposes, and undoubtedly other sets of both long and short range are scattered in a net throughout rear areas to supplement visual observation.