Our glossary contains frequently used terms and acronyms together with their explanations.


Air traffic controllers are supported in their work by state-of-the-art technology, such as radar and navigation aids covering the entire German airspace, or instrument landing systems (ILS) at the international airports in Germany. Highly qualified engineers continuously develop new air traffic control systems which are tailored to meet the demands of the air traffic controllers.

There are two basic types of radar: primary radar and secondary radar. Primary radar antennas transmit electromagnetic pulses which are reflected by the aircraft and returned to the antenna. In this way, it is possible to determine the position of each aircraft in airspace. However, this does not provide controllers with any information about the identity of the aircraft.

The secondary radar antenna, which is mounted on top of the primary radar antenna, also transmits electromagnetic signals. In contrast to the primary radar, these signals are not reflected but received by an antenna on board the aircraft. They activate a radar response which is returned to the secondary radar antenna. This signal, which consists of a four-digit number, informs the controller of the identity of the aircraft. The data appear on the controller's radar screen and enable him to identify the aircraft and assign a flight level and heading to the pilot.

Flight plan processing systems provide controllers with information about the planned course of a flight and are, at the same time, tools to compile data of the actual flight progress. Computer-based arrival and departure systems calculate optimised arrival and departure sequences.  Meteorological information systems provide controllers with the necessary weather data.

The communication systems (radio and voice switching) make it possible for air traffic controllers to coordinate all flights with pilots, adjacent sectors and air navigation service providers. For the systems of DFS are not only interconnected with aircraft but also with the systems of other ANSPs in Europe and the world.

DFS navigation aids ensure that flight routes are defined by clear fix points for the orientation of the pilots. Controllers use these fix points when issuing instructions to pilots.

DFS is not only in charge of developing technical systems but also for maintaining and repairing them.

The civil-military steering group for CNS and ATM systems keeps an eye on national and international developments in the field of civil as well as military technologies. The group's goal is to minimise capacity loss in civil aviation while handling military flight operations in a safe, efficient and cost-effective manner. For this purpose, the group will analyse current developments and check if they have any impact on operational air traffic of the armed forces or could entail operational restrictions at DFS.
This is the basis for recommendations made to civil and military units concerning special permission or specific requirements for the equipment of military.