Technology for safe flight

To ensure that aircraft reach their destinations safely, DFS provides the associated infrastructure throughout Germany. Our technicians also ensure that all equipment indispensable for air traffic control is always ready for use and up to the latest technological standards. 

Navigation, surveillance, communications

radar station Dresden
© DFS


Navigation, surveillance and communications: These three technologies are basic requirements for modern air transport. Pilots must be able to reliably find their way (navigation), air traffic control must be able to track this flight path at all times (surveillance), and pilots and air traffic controllers must be able to communicate with each other by radio or data transmission (communications). Radio beacons, radar equipment, transmitters – to name just three examples of possible technologies – guarantee safe flight from A to B. DFS maintains the necessary infrastructure throughout Germany. Our technicians also ensure that all equipment indispensable for air traffic control is always ready for use and up to the latest technological standards.



Surveillance

The highly efficient radar systems of DFS are the eyes of our air traffic controllers. They reliably track all aircraft movements in controlled airspace. A distinction is made between 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 at all times. However, this does not provide controllers with any information about the identity of the aircraft. This requires secondary radar. 

Secondary radar antennas also emit 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. A combination of numbers is transmitted which tells the controllers which aircraft it is. The data appear on the controller's radar screen and enable them to identify the aircraft and assign a flight level and heading to the pilot. They also receive additional information, such as flight level and speed. 

At the moment, DFS is in the process of upgrading all radar facilities to the state of the art, making them more modern, powerful and efficient. The new facilities require less maintenance, have a longer range and produce fewer emissions. The project is to be completed in 2030.



radar station Hamburg
© DFS
working stations in ATC center
© DFS


Communications

If you cannot use a radio, you cannot fly. All aircraft in controlled airspace are in radio contact with the air traffic controller of the air traffic control sector in which they are currently located. Because there is a lot of air traffic in European airspace, and thus many sectors, the demand for radio frequencies is also high. A stable radio link between air traffic controllers and pilots is crucial for safety. Our experts therefore ensure interference-free communication. 

It is a rare event for the radio to fail. The DFS aeronautical radio
infrastructure includes the nationwide transmitting and receiving stations, the emergency transmitting and receiving stations, and the data link stations. All systems are redundant. In the event of a malfunction, the system switches to a backup radio station. In addition, the voice switching systems at the controller working positions are not only extremely reliable, but also redundant.



Ground-based and satellite-based systems are available to air transport for navigation.  

Very high frequency omnidirectional radio beacons are located on the ground. These facilities transmit rotating radio signals which are received by aircraft. In this way, pilots know their exact position. The modern version DVOR – Doppler very high frequency omnidirectional radio range – transmits with even greater precision. DFS is currently overhauling all omnidirectional radio beacons throughout Germany.  

Modern aircraft also use satellite signals for navigation. The Global Positioning System (GPS) is used for this. Waypoints show aircraft the way. These points are defined by coordinates and are stored in the flight management system on board aircraft. The points form airways, represent crossings or mark points for a change of direction. In the terminal area of airports, aircraft pass waypoints every minute, while over the ocean, there are sometimes several hundred miles between two points.

DFS intends to reduce the number of omnidirectional radio beacons in the long term. However, the ground-based navigation systems are still needed, especially as a backup in case the satellite system should ever fail.

Ground-based navigation systems also include instrument landing systems (ILS). These systems are installed at airports and ensure that aircraft on the approach to land are on the right course and altitude.

navigation station near Frankfurt
© DFS


electronic aircraft labels
© DFS

Air traffic management systems  

Air traffic control systems consist of three main components: a radar data processing system, a flight plan data processing system and the user interface with which the air traffic controllers work. Air traffic control systems are not available off the shelf. They have to be developed over years of work specifically for air navigation service providers. Particular challenges in programming are the interaction of the different components, the functionality in different air traffic scenarios, such as terminal services or upper airspace, as well as the user-friendliness.  

DFS is constantly enhancing its air traffic management systems to be able to offer the required capacity at the customary high safety level.

Technical air navigation services personnel 

The technical facilities of DFS are maintained by highly qualified engineers and technicians. These specialists at the DFS Systems & Infrastructure Services division take care of product and service management. They play a vital role at DFS, and require a special licence to maintain the technical facilities. This means that they have to demonstrate their competence to work on specific equipment in an exam. At DFS, about 400 employees hold such a licence, which is issued by the German Federal Supervisory Office for Air Navigation Services (BAF). They maintain and repair radar facilities, radio antennas and navigation equipment, for example. System management staff with a licence also need proof of their medical fitness in a similar manner to air traffic controllers. For the licence renewals, they must regularly demonstrate their theoretical and practical knowledge. It is essential for DFS to have a sufficient number of licensed personnel – this is the only way to ensure orderly air navigation services operations. 


 

employee at the radar station
© DFS


Remote tower control

Does every airport still need a control tower? Many air navigation service providers are increasingly backing the remote tower control (RTC) concept. With RTC, air traffic controllers handle traffic at the airport not from a control tower on site but from a distant control centre using camera technology. DFS and the Austrian high-tech company Frequentis have together developed a particularly advanced solution. The view from the tower cab is replaced by one delivered from a camera tower equipped with both static and pan-tilt-zoom video and infrared cameras. The system also supports air traffic controllers in doing their work by automatically detecting and tracking aircraft and other targets. 

At Saarbrücken Airport, the system has been successfully in use since the end of 2018, and at Erfurt Airport since 2022. The controllers who provide air traffic control for these airports are based more than 400 kilometres away – at the Remote Tower Control Centre in Leipzig, in the east of Germany. DFS plans to monitor other airports from this location in the future. Dresden Airport is to follow and will be equipped with camera systems and integrated into the Leipzig centre. DFS has also founded the subsidiary Frequentis DFS Aerosense (Aerosense) together with Frequentis to market its remote tower solution worldwide.

www.aerosense.solutions