CNS

 

Investing into the air traffic control system and its modernization in the previous period have ensured that the existing infrastructure in its current operational condition is in full compliance with the international standards and requirements in terms of capacity and functionality.

CNS infrastructure within SMATSA llc is made up of accurate, reliable and long-lasting technical systems featuring high level of automation and low maintenance requirements, which fulfill contemporary environmental protection standards. CNS infrastructure within SMATSA llc consists of:

The FAMUS modernization project involved, upon the completion of the installing and testing processes, commissioning of the systems used in air traffic control service provision, whose introduction enabled the commencement of the operational work in the new Air Traffic Control Center building. The FAMUS project involved modernization of Digital Voice Recording and Playback Systems (DVRPS) and Time Reference Systems (TRS) in aerodrome control units, as well as modernization of navigation aids.

 

Automated Air Traffic Control Systems

Automated air traffic control systems include:

  • AFTN/AMHS,
  • DPS (Data Processing System).

AFTN/AMHS

AFTN/AMHS is used for generation and exchange of messages in the Aeronautical Fixed Telecommunication Network (AFTN). In the future implementation phase the system shall also be used for generation and exchange of messages within the Aeronautical Message Handling System (AMHS).

AFTN/AMHS is physically divided into two functional units:

  • Operational AFTN/AMHS unit,
  • Test AFTN/AMHS unit, which is primarily used for training of operational and technical personnel, but is also used for testing of new system configurations, whose functionality is impossible to check within the operational system.

The operational and the test systems are functionally identical, the only difference being that the operational system is redundant, whereas the test system has no redundancy in regard to hardware and software configuration. The operational and the test system interconnection enables availability of real messages in the test environment, which enhances not only the quality of the personnel training but also the reliability of the test results.

Depending on the primary function, AFTN/AMHS is divided in:

  • AIDA-NG system, used for the exchange of AFTN/AMHS messages with the international partners (currently available AFTN connection with Vienna, Budapest, Bucharest, Sofia, Athens and Banja Luka), and
  • CADAS system, used for the exchange of AFTN/AMHS messages with domestic users in Beograd ATCC, Beograd Tower, Podgorica ТМА, as well as in Batajnica, Vršac, Niš, Kraljevo, Užice, and Tivat aerodrome control units.

DPS

DPS is a complex multiple-purpose system, which, among other things, comprises:

  • Surveillance Data Processing System (SDPS), including:
  • Sensor Data Conversion and Distribution Systems (radar and ADS-B data),
  • Sensor Data Tracking Systems forwarding generated tracks to the controller working positions and other system users,
  • Sensor Data Recording and Playback System,
  • Flight Data Processing System (FDPS),
  • Safety Nets and Monitoring Aids System,
  • System for establishing connection between the part of the system set up in Belgrade and the part of the system set up in Podgorica.

SDPS provides the air traffic control officer with the information on the true aircraft position, whereas FDPS processes all flight-related data (e.g. aerodrome of departure and calculated take-off time, aerodrome of destination and landing time, requested flight level, aircraft type and appropriate equipment, etc.). SDPS and FDPS are interconnected, which enables coupling of the true aircraft position data and the flight plan data, further enabling Air Situation Display function, potential conflict identification function and alert function, and consequently facilitating work of an air traffic control officer.

Local FDPS in Belgrade is connected to global systems through which it receives initial flight plans, but is also connected to other surrounding local FDPS with which it exchanges data related to flights transferring from one air traffic control unit area of jurisdiction to another. Coordination between adjacent air traffic control units is supported with the exchange of OLDI (On-Line Data Interchange) messages (currently available OLDI connection with neighboring partners Budapest, Zagreb, Sofia, Skopje, Tirana, Arad, Brindisi and Bucharest).

DPS is physically divided into two functional units (subsystems):

  • Operational DPS, which is redundant,
  • Test DPS, which is primarily used for testing of new system configurations and parameters prior to allowing their operational use, but also for training of technical personnel. Test system is a functional copy of the operational DPS, the only difference being that the test system is singular.

 

Telecommunications Systems

The role of the telecommunications systems within the air traffic control system is the provision of the following services:

  1. Air-ground pilot-controller voice communication, for the purpose of coordination of aircraft in flight;
  2. Ground-ground voice communication between adjacent air traffic control units, for the purpose of coordination of aircraft in flight;
  3. Voice communication recording;
  4. Reference time distribution;
  5. Transfer of voice communication and of OLDI, AFTN, МЕТЕО and radar data as well as of the data required for the surveillance of navigation and electronic power equipment.

Voice communication system comprises independent commutation blocks in simultaneous operation and redundant interface controllers, with specifically distributed software solution contributing to its high reliability and availability. In case of the main system failure, voice coordination is accomplished through a completely independent backup system.

Radio system used for the needs of air-ground voice communication performance comprises a group of distributed radio centers, in order to achieve the best possible radio signal coverage. All radio center signals are collected in the Air Traffic Control Center through telecommunications network owned by SMATSA llc as well as through the infrastructure belonging to telecommunications service providers. Using of redundant transfer paths has been made available wherever technical justification exists.

Beograd ATCC

Each aerodrome has its own local radio center used for handling ground-air communication in its area of responsibility. All frequencies used for the needs of air-ground voice communication are coordinated at the international level under the ICAO and EUROCONTROL supervision.

One of the radio centers

 

Due to the legal obligation of recording and filing of all the data relating to the process of air traffic control service provision, a system has been developed and installed, for recording operational voice communication performed within Beograd ATCC as well as within all aerodrome and terminal air traffic control units.

High percentage of the rate of availability of the telecommunications services is significantly influenced by the existence of detailed technical instructions, prescribed preventive system maintenance procedures, professional development training and refresher training courses organized for the personnel performing the telecommunications-related jobs.

 

Radar Systems

The system of surveillance of the air traffic under the jurisdiction of SMATSA llc relies on the use of up-to-date Primary Surveillance Radar (PSR) and Secondary Surveillance Radar (MSSR/Mode S) systems, combined with the intensive following of the development of new technologies (multilateration, ADS-B, etc.). All secondary surveillance radars feature basic and advanced, Mode S, operation modes, whereas primary surveillance radars have the ability of generating weаther data. At the moment, the surveillance of the air traffic is carried out through four radar stations with three co-located primary and secondary radars installed, backed up with the radar data obtained through the exchange with the neighboring ANSP. Operation of the mentioned systems provides data required for multi-radar tracking and ensures fulfillment of the following requirements in accordance with the European air traffic surveillance standard:

  • double area secondary radar coverage,
  • double secondary radar coverage and single primary radar coverage in the main terminal control areas.

Working methods and regulatory requirements for the provision of the Surveillance service within the CNS service have been brought into compliance with the relevant ICAO Annexes and documents, national laws and regulations, as well as with the recommendations defined by the EUROCONTROL. The integrity, continuity, availability and accuracy of the data are guaranteed by application of technical procedures and operational instructions, by system design, by equipment redundancy as well as by 24-hour technical supervision and management of the systems by competent personnel.

Koševac Radar Station

Koviona Radar Station Technical Facility

 

Ground Based Radio Navigation Systems

Ground based radio navigation aids are used in the air traffic control system in order to ensure safe en-route navigation, but also to enable the application of aerodrome instrument departure i.e. approach and landing procedures. These systems provide, at any moment, the flight crew with the possibility of determining the aircraft relative position, within the entire airspace under SMATSA llc jurisdiction, enabling the aircraft to stay on its planned course in all weather conditions. Ground based radio navigation systems are, therefore, fundamental aids in guiding the aircraft towards their destination, no matter whether they are en-route or aerodrome aids.

The main radio navigation aids within Serbia and Montenegro Air Traffic Services SMATSA llc navigation infrastructure are: ILS, VOR, DME, NDB and VDF.

Since the final approach and landing are the most complicated phases of flight, SMATSA llc is equipped with several ILS systems that enable precision instrument approach and safe landing of the aircraft, even during the low visibility conditions. ILS consists of the localizer that provides aircraft with lateral guidance, glide path that provides vertical guidance and marker beacons. The localizer guides the aircraft along the extended centreline of the runway, whereas the glide path ensures the descent of the aircraft along the glide-slope which is usually at the angle of 3º in relation to the horizontal plane. Marker beacons provide indication when the aircraft is at the predefined points/distances along the approach path.

VOR (VHF Omni-Directional Radio Range) is a medium-range navigation aid transmitting the azimuth information. It is located along the air routes, as well as in the vicinity of the aerodromes. If the aircraft is equipped with the appropriate equipment, the pilot can determine the aircraft magnetic course in relation to the position of VOR on the ground.

DME (Distance Measuring Equipment) could be located together with VOR, so as to complement the azimuth information with the aircraft slant-range distance from VOR/DME station on the ground. The crew is provided, in this way, with all the data necessary for determining precise position of the aircraft. DME could also be coupled with ILS – instead of marker beacons, thus providing continuous information about the distance from the runway threshold.

NDB (Non-Directional Radio Beacon) is one of the earliest radio navigation aids. It is used to guide the aircraft along the air routes as well as in non-precision instrument approach for landing at the aerodrome. NDB transmits information about the aircraft relative bearing in relation to the ground station.

VDF (VHF Direction-Finding) is auxiliary navigation aid used to establish the aircraft position by determining the direction from which the radio communication, transmitted by it, is received. VDF receiver is usually located within the aerodrome complex.

 

Glide Path VOR/DME
VDF
ILS Localizer Beograd ILS Localizer

 

Automated Weather Observation Systems (AWOS) and Equipment

Landing at and taking off from an aerodrome depend to a large extent on current weather conditions at the aerodrome. Therefore, meteorological information is of key importance for the safety of air traffic. Automatic weather stations, which represent the main source of information, have been set up at all aerodromes in the territory of the Republic of Serbia and of the Republic of Montenegro, with the purpose of permanent measuring, collecting, processing, filing, display and exchange of meteorological data. Automatic weather stations consist of:

  • sensors for measuring wind direction, wind speed, visibility, cloud height, atmospheric pressure, humidity, air and ground temperature, precipitation, etc;
  • acquisition unit for reception, adjustment and forwarding the data for further processing;
  • dual servers (sensor operation control, data processing, filing, transferring data to the users);
  • terminal / work stations for data display.

Anemometer

During take-off, precision approach and landing procedures in the reduced visibility conditions, apart from cloud base, the values of the Runway Visual Range (RVR) parameters are of importance. Automated system at the aerodrome in Belgrade provides these data, which was one of the conditions for establishment of operational Cat IIIb category at Nikola Tesla Airport in Belgrade.

Together with the software package for meteorological data display (SAWAS), the system includes provision of meteorological reports such as METAR, SPECI, TAF, SIGMET, AIRMET, AD WRNG, etc., which are generated either automatically or by the weather forecasters and meteorological technicians.

 

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