Communications Systems

Communications Systems Communications are the backbone of the implementation of efficient and safe air traffic control. Fast and reliable setting up of voice communication between the air traffic control centers and a large number of aircraft (Air-Ground communication), as well as among the ATC centers in Croatia and those abroad (Ground-Ground communication) is one of the major prerequisites for the provision of air traffic control services. 
The architecture of voice communication systems is as redundant, safe and manageable as possible, which enables the continuous provision of air traffic control services, even in the cases of a breakdown of one of its segments.

The available communication infrastructure includes a few systems making a functional unit, and some of them are:
  • Voice Communication and Control Systems - VCCS,
  • Back-up Voice Communication and Control Systems,
  • VHF and UHF radio systems on multiple locations through the country,
  • Voice Recording and Replay Systems - VRRS,
  • Own portable telecommunication infrastructure (microwave links and network of multiplexers).
Voice Communication and Control Systems are installed at the Zagreb ACC and at almost all airports in Croatia. These systems enable fast and efficient allocation of all communication resources (A-G and G-G) that an air traffic controller needs to establish communication with the aircraft and neighboring ATS units. 

VHF/UHF radio systems for A-G communication are installed in multiple radio centers throughout the county in order to ensure quality coverage of the whole airspace under responsibility of Croatia Control, as well as the provision of all types of ATC services. All VHF radio frequencies for A-G communication are harmonized on international level and are registered in the central register of the ICAO, which is managed by NM.

The UHF frequencies in Croatia, as in all other NATO States, are collectively managed by the NATO Frequency Management Sub-Committee, with the technical and administrative support of the Spectrum Management Branch (SMB) located at NATO Headquarters in Brussels. Croatia Control is responsible for international coordination, allocation and registration of VHF frequencies which are operational within the Zagreb FIR.

Due care is given to following the trends in communication systems development so that the preconditions for increasing the air traffic safety and the improvement of general level of air traffic control and management could be met through continuous modernization. Development and implementation of own broadband telecommunication TDM and IP network is currently under way, thus creating the prerequisites for gradual migration of communication systems to an IP protocol based network.