Communication, Navigation, Surveillance (CNS) services is one of the five air navigation services that Vietnam Air Traffic Management Corporation (VATM) provides for flights from/to the airports of Viet Nam and transit flights through Viet Nam’s flight information region.

Figure 1: Moc Chau VHF Station 1:

Figure 2: VHF Transmitting/Receiving Stations and Coverage

With the current VHF system, the majority of the Viet Nam’s flight information regions are in VHF coverage. However, due to terrain conditions there remains a part of the Ho Chi Minh flight information region in the East Sea that VHF communication has not reached yet. In this area, the air traffic controllers communicate with the pilot using digital data messages of CPDLC (Controller Pilot Data Link Communications) method via the satellite transmission. Moreover, the HF air-to-ground radio station is installed at Tan Son Nhat International airport as a standby communication medium for the oceanic airspace

1.2. Aeronautical Fixed Services includes two types:

• The first type is ATS/DS (Air Traffic Service/Direct Speech). This is a telephone circuit for direct exchange of information between air traffic services (ATS) units and between ATS units and other relevant offices. This communication uses direct speech (Hotline).
• The second type is Aeronautical Fixed Telecommunication Network – (AFTN). This is a text transmission communication network between the units related to air navigation services, airports, airlines and aviation authorities. Currently, there are four Automatic Message Switching System (AMSS) located at Noi Bai, Ho Chi Minh, Da Nang and Gia Lam.

Figure 3: Viet Nam’s AFTN network connection diagram

2. Navigation services

Navigation services are provided through aeronautical radio navigation aids that signal to aircraft to acknowledge the position and the direction against the navigation aids station during en-route, approach and landing phases.

VATM currently provides navigation services from the following navigation aids stations:

• Three NDB (Non Directional Beacon) stations installed in Moc Chau, Nam Dinh and Long Khanh;

• Nineteen VOR/DME (Very High Frequency Omnidirectional radio Range/ Distance Measuring Equipment)  stations installed in Dien Bien, Noi Bai, Western Noi Bai, Nam Ha, Cat Bi, Vinh, Dong Hoi, Da Nang, Phu Bai, Pleiku, Phu Cat, Buon Me Thuot, Cam Ranh, Lien Khuong, Phan Thiet, Tan Son Nhat, Phu Quoc, Can Tho and Con Son.

Figure 4: DVOR/DME station

Surveillance services are provided through surveillance radar systems and RDP/FDP systems to help the air traffic controllers identify the position of the aircraft on the radar screen at the Controller Workstation Positions (CWPs). The majority of the Viet Nam’s flight information regions has been covered by six Secondary Surveillance Radar systems. There remains a part of the Ho Chi Minh flight information region in the East Sea that radar coverage has not reached yet. In this area, the aircraft’s position information are provided by ADS-C application via the satellite transmission (together with CPDLC). Moreover, three Primary Surveillance Radar systems are installed at the international airports of Noi Bai, Da Nang, Tan Son Nhat that cater for  approach control service;  Currently, VATM has 02 RDP/FDP systems at Ha Noi ACC and Ho Chi Minh AACC.

Figure 5: The coverage of Viet Nam’s secondary surveillance radar systems

The radar systems are categorized based on their functions as follows:

• En-route radar: L band frequency range (1-2 GHz), antenna rotation speed of 6-12 rpm; located on the mountain for a broad range of coverage and not be  obscured by the obstacles; located far from the center for maximum coverage. In the FIR there are often many radar systems installed to ensure the coverage overlap and mutual redundancy. Coverage from 200-250 nm (400-450 km).
• Airport radar: S band frequency range (2-4 GHz), antenna rotation speed of 12-15 rpm; located within the airport to monitor the aircraft in the  approach and takeoff, landing areas on the runway. Coverage from 60-80 NM (100-150km).
• Surface Movement Radar - SMR: X band frequency range (8-12 GHz) or Ku (12-18 GHz), antenna rotation speed of 60 rpm; located on top of the aerodrome control tower (TWR), about 40-100m, near the center of taxiways and apron so that the air traffic controllers can observe the taxiing of aircraft and traffic within these areas. Coverage of about 5 km.

 Figure 6: Noi Bai radar station

In recent years, along with the investment in technological innovation and upgrading the flight control units, the Corporation has invested in purchasing technical equipment and systems, applying digital technology and satellite information to improve the quality of communication, navigation and surveillance.

On October, 19^th 2011, the Minister of Transport signed a decision on approving the master plan to develop communication, navigation, surveillance and air traffic management (CNS/ATM) of Viet Nam's civil aviation up to 2020 and development orientation toward 2030. According to this plan, the applications of satellite data communications will gradually replace VHF, HF voice communications; proceed to apply the Performance-Based Navigation (PBN) and Ground Based Augmentation System (GBAS); deploy the installation of Automatic Dependent Surveillance - Broadcast (ADS-B) to broaden ADS-B coverage over the Viet Nam’s FIRs.

With the modern equipment/system and advanced technology, with qualified human resources, Viet Nam’s air traffic management meets the rigorous standards and requirements of the air traffic management and, at the same time, is available to assist and coordinate with air traffic control centers of the adjacent countries in order to ensure aviation safety and contribute to the development of the air transport in the Asia/Pacific region. 

Editorial Board