11.17.2 Phraseology BREAK BREAK is used to indicate the separation between messages
transmitted to different aircraft in a very busy environment. It is also used for controlling multiple aircraft flying in formation.
JL 102 RWY 27 WIND 280 DEGREES 5 KNOTS, CLEAR TO LAND, BREAK BREAK, IC444 ORBIT LEFT FOR DELAY, BREAK BREAK, VBB EXTEND DOWNWIND
CHAPTER 12 HF COMMUNICATIONS 12.1 Introduction
While the V/UHF are used for terminal communications, HF is used for en-route i.e. long distance communications. HF has the advantage of reaching much farther distance than the V/UHF radio waves. On the negative side, HF channels are much noisier than V/UHF communications. HF communication is being replaced by Remote Controlled Air Ground (RCAG) and satellite communications (SATCOM) which use VHF and UHF frequencies.
12.2 Definitions
Radiotelephony network is defined as a group of radiotelephony aeronautical stations which
operate on and guard frequencies from the same family and which support each other in a defined manner to ensure maximum dependability of air-ground communications and dissemination of air- ground traffic.
Network station An aeronautical station forming a part of a radiotelephony network.
Regular station A station selected from those forming an enroute air-ground radiotelephony
network to communicate with or to intercept communications from aircraft in normal conditions.
Primary guard station Regular station that has the responsibility of providing the primary guard (monitoring the frequency) so that continuity of air-ground communications is ensured and messages from the aircraft can be effectively handled.
12.3 Principles of Network Operation
The aeronautical stations of a radiotelephony network should assist each other in order to provide the air-ground communication service required of the network by aircraft flying on the air routes for which the network is responsible. (PANS)
The regular station will be those serving the locations immediately concerned with flights on that route segment, i.e. points of take-off and landing and appropriate flight information centres or area control centres and, in some cases, additional suitably located stations required to complete the communication coverage or for intercept purposes. (PANS)
In areas or on routes where radio conditions, length of flights or distance between aeronautical stations require additional measures to ensure continuity of air-ground communications throughout the route segment, the regular stations should share between them a responsibility of
primary guard whereby each station will provide the primary guard for that portion of the flight
during which the messages from the aircraft can be handled most effectively by that station. (PANS) During its tenure of primary guard, each regular station should, among other things:
(a) be responsible for designating suitable primary and secondary frequencies for its communications with the aircraft;
(b) receive all position reports and handle other messages from and to the aircraft essential to the safe conduct of the flight;
(c) be responsible for the action required in case of failure of communication. (PANS)
The transfer of primary guard from one station to the next will normally take place at the time of the traversing of flight information region or control area boundaries, this guard being provided at any time, as far as possible, by the station serving the flight information centre or area control centre in whose area the aircraft is flying. However, where communication conditions so demand, a station may be required to retain primary guard beyond such geographical boundaries or release its guard before the aircraft reaches the boundary, if appreciable improvement in air-ground communication can be effected thereby. (PANS)
12.3.1 MWARA and RDARA
Based on the above principles, radiotelephony networks have been divided as Major World Air Route Area (MWARA) networks and Regional and Domestic Air Route Area (RDARA) networks.
12.3.1.1 Major Air Route Area Networks (MWARA)
Vast areas of the world lack the necessary VHF radio communication systems needed to provide reliable radio coverage between aircrews and air traffic controllers. The lack of VHF coverage within most of these areas is due to the very remote location of these regions, for example much of the airspace over the oceans lack VHF communications as it is impossible to install transmitters on a reliable platform within these regions. For the purpose of establishing communications a vast network of HF Frequencies has been allocated to provide voice communications between aircrew and ATC facilities. Some of these regions will have as many as six different groups of frequencies assigned to them.
Aircraft operating international services to/from India operate in the following MWARA networks:
(a) Indian Ocean Area – 1 (INO – 1)
Coverage area: Antananarivo, Beira, Mumbai, Brisbane, Coco Islands, Colombo, Dar es Salaam, Harare, Jeddah, Kigali, Lilongwe, Lusaka, Chennai, Mahajanga, Male, Mauritius, Moroni, Nairobi, Perth, Seychelles, St.Denis, Toamasina
(b) South East Asia -1 (SEA – 1)
Coverage area: Bali, Bangkok, Colombo, Kolkota, Dhaka, Guangzhou, Jakarta, Kathmandu, Kuala Lumpur, Kunming, Chennai, Male, Singapore, Yangon
(c) Middle East Asia – 2 (MID – 2)
Coverage area: Abadan, Almaty, Ashkabad, Bishkek, Mumbai, Delhi, Dushanbe, Kabul, Karachi, Kathmandu, Kuwait, Lahore, Male, Muscat, Odessa, Samarkhand, Seychelles, Tashkent, Tehran, Tbilisi, Urumqi, Yerevan
12.3.1.2 Regional and Domestic Air Route Area Networks (RDARA)
For domestic en-route usage, India is divided into five areas, each area having its own family of frequencies. Aircraft communicate on these frequencies as appropriate to the area in which they operate. The RDARAs are designated as Northern, Western, Southern, Eastern and North East. Coverage area of each RDARA is normally the FIR. All the aeronautical stations within the coverage area of an FIR will guard the frequency family designated for that FIR.
12.3.1.3 The list of FIRs and the frequencies (MWARA and RDARA) are given in the table
Table 12.1 Flight Information Regions, MWARA and RDARA frequencies FIR Unit providingservice
Call sign Language
Hours of service Frequencies
Chennai Chennai Radio (MWARA) Chennai Radio English H24 17907 KHz, 13318 KHz, 11285 KHz, 6655 KHz, 5670 KHz, 3470 KHz Chennai Radio (RDARA) Chennai Radio English H24 8861 KHz, 6655 KHz, 6583 KHz, 2872 KHz Delhi Delhi Radio (MWARA) Delhi Radio English H24 13288 KHz, 10018 KHz, 5658 KHz, 3467 KHz Delhi Radio (RDARA) Delhi Radio English H24 8948 KHz, 8906 KHz, 5601 KHz, 5580 KHz, 2872 KHz
Guwahati Guwahati Radio Guwahati RadioEnglish HS 8948 KHz, 5484 KHz, 2923 KHz Kolkota Kolkota Radio (MWARA) Kolkota Radio English H24 10066 KHz, 6556 KHz, 3491 KHz, 2947 KHz Kolkota Radio (RDARA) Kolkota Radio English H24 8906 KHz, 8861 KHz, 6583 KHz, 5583 KHz, 2972 KHz Mumbai Mumbai Radio (MWARA) Mumbai Radio English H24 13288 KHz, 11300 KHz, 10018 KHz, 8879 KHz, 5658 KHz, 5634 KHz, 5601 KHz, 3467 KHz, 2872 KHz Mumbai Radio (RDARA) Mumbai Radio English H24 8948 KHz, 8909 KHz, 6655 KHz, 5601 KHz, 2872 KHz 12.4 Frequencies to be Used
Aircraft stations shall operate on the appropriate radio frequencies. The air-ground control radio station shall designate the frequency(ies) to be used under normal conditions by aircraft stations operating under its control.
In network operation, the initial designation of primary and secondary frequencies should be made by the network station with which the aircraft makes pre-flight check or its initial contact after take-off. This station should also ensure that other network stations are advised, as required, of the frequency(ies) designated. (PANS)
An aeronautical station, when designating frequencies in accordance with, should take into account the appropriate propagation data and distance over which communications are required.
If a frequency designated by an aeronautical station proves to be unsuitable, the aircraft station should suggest an alternative frequency.
When, air-ground frequencies are used for the exchange between network stations of messages essential for coordination and cooperation between the stations, such communication should, so far as possible, be effected over network frequencies not being used at that time for the bulk of the air-ground traffic. In all cases, the communication with aircraft stations should take priority over the inter-ground station communications. (PANS)
12.5 Establishment of Communications
12.5.1 Initiating a call on the HF is similar to that of VHF communications i.e. called station call
sign followed by the call sign of the calling station shall be transmitted. The difference in HF communications is, at the end of each transmission, the RT phraseology OVER is used. When the exchange of traffic has ended, the RT phraseology OUT is used.
CHENNAI RDO VTAME