Most important technical systems used in air navigation

The technical systems used by Finavia's air navigation services can be divided into five different groups. The hardware systems used in air traffic control usually fall within the ATM or COM device groups.


1. Air traffic control systems (ATM)

Air traffic services are provided for aircraft and other airspace users at air traffic control workstations using air traffic management systems (ATM), as well as direction and monitoring services for ground transport in the airport's manoeuvring area.

The main system in Finland is the Eurocat radar display and air traffic management system. It is used by the air traffic control units or workstations (sectors) who are responsible for the various airspace sectors to coordinate and monitor traffic flows. The WinRADAR and UBFS systems are used as backup devices for radar air traffic control. The eSTRIP system is used for coordination between the workstations and for controlling traffic at Helsinki-Vantaa.

2. Radar and surveillance systems (SUR)

Radar and surveillance systems enable the creation of an air situation picture for display and air traffic management systems. Various radar devices produce target information, which is overlaid onto the display terminal for flight planning information.

Commercial traffic is directed by the air traffic control units largely on the basis of secondary surveillance radar (SSR) information produced using a secondary radar transponder. Using this technology, the radar device ‘asks' the aircraft its identification data, altitude and other information relating to the flight (route point, direction, speed, take-off/landing speed), to which the transponder gives the answer.

In the largest sectors or the most critical airspace sectors, secondary radar information is complemented with primary radar information (PSR), which is based directly on the reflection of radio waves from the aircraft's frame and therefore no special requirements are required from the aircraft or other airspace user being monitored. PSR radar information is also based on the image produced by ground transport surveillance radars at Helsinki-Vantaa Airport.

The angle of arrival of an incoming radiotelephone transmission can also be measured by nearly all air traffic control units and thereby the direction of the aircraft sending the transmission in relation to the airport can be observed.

3. Navigation systems (NAV)

Aircraft have traditionally navigated within different airspace sectors on the basis of navigational devices located on the ground. Most routes are still based on the locations of ground stations, with aircraft flying along the ‘corridors' established by these points on the ground.

However, the possibilities provided by satellite-based positioning devices are changing the traditional basis for planning based on ground stations. Finavia publishes GPS-based approach procedures for airports every year to support traditional navigation systems.

The ILS system enables aircraft to approach and land on runways even when there is bad visibility.

4. Telecommunication and communications systems (COM, DAT)

The communications and telecommunication systems used in air navigation enable contact between the air traffic control units as well as contact between aircraft and air traffic control. Information on flight plans and airspace use are transferred internationally using the internal aviation data network AFTN (Aeronautical Fixed Telecommunication Network).

Meteorological information and air traffic control clearances can be communicated to aircraft via advanced systems using data links, but a radiotelephone using a VHF frequency band is still the most commonly used communication method in aviation.

Each air traffic control unit has its own radio frequency, which is published in aviation maps in the AIP (Aeronautical Information Publication). It is a statutory requirement for aircraft flying in all controlled airspace sectors to have a VHF radio.

The national aviation authority, the Finnish Civil Aviation Authority, is responsible for controlling the aviation frequency band and for coordinating the frequency between neighbouring countries and national actors. Finavia maintains the radio systems used at its own airports in accordance with the regulations set by the Finnish Civil Aviation Authority.

5. Meteorological observation systems (MET)

Finavia is responsible for providing aviation meteorological observations at its airports. Meteorological observations are taken (METAR) at 20 minute intervals at the airports and the information is transmitted using the aviation telecommunication network (AFTN) all over the world as a basis for flight planning.

The variables measured are visibility, cloud ceiling and weather conditions, as well as the temperature, condensation point, wind and pressure. For some of the aerodromes, the observations are produced entirely automatically, and in this case there will also be lightning and ice sensors in addition to weather radar information from the Finnish Meteorological Institute.

On the basis of the meteorological observations produced by Finavia, the Finnish Meteorological Institute produces the flight weather forecasts (FAT, GAFOR, SWC) for flight planning. Finavia's briefing points at the airports or online service portal are the places where pilots can search for this information.