PAGE: 1 Table of Contents Table of Contents... 1 CHAPTER 11.-... 3 11.1 Fixed Communication... 3 11.1.1 Communication Message... 3 11.1.1.1 Message Composition... 3 11.1.1.1.1 The 2-letter priority indicators are:... 3 11.1.1.1.2 Origin and Identity... 4 11.1.1.1.3 Text... 4 11.1.1.2 Correction of Messages... 4 11.1.1.3 Flight Information Messages... 4 11.1.2 Description of Aircraft Movement Message... 5 11.1.2.1 Examples of Aircraft Movement Message... 5 11.1.2.2 Examples of Aircraft Diversion Message... 7 11.2 The AFTN Aeronautical Network... 7 11.2.1 Message Heading... 7 11.2.1.1 Circuit Identification... 7 11.2.1.2 Channel-Sequence Number... 8 11.2.1.3 Priority... 8 11.2.1.4 Address... 8 11.2.1.5 Origin... 9 11.2.1.6 Text... 9 11.2.1.7 Message Ending... 9 11.3 Mobile Communication... 9 11.3.1 General... 9 11.3.2 Company Utility Telecommunication Channel (CUT)... 10 11.3.2.1 Utilization of the CUT... 11 11.3.2.2 Guard of the CUT... 11
PAGE: 2 11.3.2.3 Operational Control of Facilities... 11 11.4 Long Range Company Operational Control Radio Service... 12
PAGE: 3 CHAPTER 11.- 11.1 Fixed Communication 11.1.1 Communication Message The purpose of Communication Message is to provide and operate a communications system for the exclusive use by include AC AVIATION. 11.1.1.1 Message Composition Messages for the communication shall consist of the following compositions: (a) Message Heading Every message must start with a message heading. Normally the message heading is referred to as Start-of-Message (SOM). (b) Message Priority Messages will be forwarded over the SITA network according to their handling priorities. Message which do not require special handling are to be transmitted without a priority indicator. If special handling is required, this shall be indicated by a 2-letter priority indicator, preceding the first address and separated from it by a space. 11.1.1.1.1 The 2-letter priority indicators are: QS - Emergency or Distress Messages This priority shall be used only for top urgent messages i.e. message concerning the safety of human life or the safety of the aircraft in flight. QX - Urgent Operational Messages This priority shall be used for flight operations in progress, i.e. Flight Movement Messages. QU - Urgent Messages This priority shall be used for any other urgent messages. However, this indicator cannot be used to indicate a need for an expedient reply from the addressee. For this purpose, the word URGENT shall be given as a first text word..qd - Deferred Messages The transmission of messages with the priority QD may be delayed. They will be transmitted over the network after traffic of higher priority. OD-messages are normally delivered fast enough to serve most requirements for telegraphic forwarding of information, i.e. within a few hours. Messages should always be sent with the priority QD if they are intended for transmission to other continents where office hours are different from the originator except for messages intended for computer processing.
PAGE: 4 Transmission priority Messages handling Priority indicator 1 Emergency QS 2 Urgent QU and QX 3 Normal 4 Deferred QD 11.1.1.1.2 Origin and Identity Message origin and identity are mandatory. They shall be given on the line between address and text sections, starting the line with full stop sign (.). The message originator and the identity shall be separated by a space. The origin group shall be composed in the same way as address group. If a time reference is used for message identity, it shall consist of a date/time group in Coordinated Universal Time (UTC). 11.1.1.1.3 Text Messages will occupy circuit time in direct proportion to the message length. Keeping messages short by the use of abbreviations or word contractions can shorten the transmission time of the messages and leave more space on the network for other messages. 11.1.1.2 Correction of Messages Error in messages composed on a display set shall always be corrected before pressing the ENTER key. When an error has been discovered before the transmission of the message, the whole message must be retyped. The letter "E" shall not be used to indicate an error. When an error has been observed after the Message Ending, it is necessary to send a new complete message. To identify such messages, the standard message identifier (COR) must be shown on the first text line. 11.1.1.3 Flight Information Messages There are various types of Flight Information Messages concerning Dispatch Services. (a) Aircraft Movement Message () It is comprised of Departure, Arrival, and Delay Messages. (b) Aircraft Diversion Message (DIV) Shall be used whenever the destination of a flight enroute is changed. (c) AD HOC Schedule Message (ASM) Shall be used for the transmission of a deviation from the basic schedule, such as an addition of a supplementary or an extra flight, change of an existing flight in routing, timing, equipment or other data and cancellation of a flight. These messages shall be composed and forwarded in accordance with the standards established by IATA. The standard message formats will be used for manual processing as well as machine-issued messages.
PAGE: 5 These messages shall be dispatched by the personnel who are responsible for the handling of a flight at the certain station immediately: After the departure or arrival of an aircraft or as soon as the delay is known for message. After the information becomes available at the airport first receiving notification of the diversion regardless the reason for DIV message. Prior to the actual departure from the station concerned, and shall be regarded as a firm amendment to the basic schedules except for punctuality rules which may vary from airline to airline in case of ASM message. All dates/times will be expressed in UTC consisting of 4-digit time group (hours within the range of 0000 to 2359 hours). Airport identifiers shall be used by IATA 3-letter code. Note 1: In case of missing Aircraft Movement Message for a certain flight within a predetermined time limit, a Request Information Message shall be sent with 2 possible formats: RQM ACJ04/22. UTH.ADIDL Or MIS AD ACJ04 22OCT UTH Note 2: On the contrary, once receiving a Request Information Message for any relevant flights, an Aircraft Movement Message, no matter of a Departure, Arrival, or Delay message, shall be sent as soon as possible. 11.1.2 Description of Aircraft Movement Message Supplementary Information Note: Any other information pertaining to aircraft movement may be printed at the bottom of the Message. It may show delay reasons in plain language or other company requirement. 11.1.2.1 Examples of Aircraft Movement Message Example 1 - departure message: ACJ04/22.HSPEK.BKK AD0800/0820 EA0910 UTH PX2 SI TOW 23080 MTOF 10000 Example 2 - departure message including actual delay information: ACJ04/22.HSPEK.BKK AD0650/0703 EA0753 UTH DL93/0020 PX2 SI TOW 23080 TOF 10000 Example 3 - arrival message: ACJ04/22.HSPEK.BKK AA0230/0235
PAGE: 6 Example 4 - delay message: ACJ04/22.HSPEK.BKK ED220800 DL41 Or in case of indefinite delay: ACJ04/22.HSPEK.BKK NI220900 SI GENERATOR TROUBLE Example 5 - delayed takeoff message: ACJ04/22.HSPEK.UTH AD1945 EO2005 SI DEICING Or ACJ04/22.HSPEK.UTH AD1945 E02005 EA 0745 BKK DL72 SI DEICING Example 6 - return to ramp message ACJ04/22.HSPEK.BKK AD0610 RR0630 SI ABORTED TAKEOFF Or ACJ04/22.HSPEK.BKK AD0610 RR0630 DL90/0010 SI ABORTED TAKEOFF Example 7 - return from airborne message ACJ04/22.HSPEK.BKK FR1200/1215 SI BIRD STRIKE ENG 2 Example 8 - revised estimated time of arrival: ACJ04.HSPEK.UTH EA0320 SI HOLDING DUE TO TRAFFIC Example 9 - arrival taxi time variance information message: ACJ04/22.HSPEK.UTH AA1750 EB1810 SI NO STAND AVAILABLE
PAGE: 7 11.1.2.2 Examples of Aircraft Diversion Message Example: diversion message: DIV ACJ04/22.HSPEK.UTH EA2245 KKC DR71 PX2 SI LOW STRATUS SEL Or ACJ04/22.HSPEK.UTH EA0415 KKC PX2 SI PAX REQUIRED MEDICAL ATTN 11.2 The AFTN Aeronautical Network Aeronautical Fixed Telecommunications Network (AFTN) is operated by or on behalf of member states of the International Civil Aviation Organization (ICAO) with the objective of ensuring telecommunications necessary for safety, regularity and efficiency of International Air Navigation is established. According to ICAO a regulation which is governing the use of the network, aircraft operating agencies may tender for the transmission over AFTN circuits only certain specified categories of messages concerning safety, regularity and efficiency of airline operations. The following categories of messages are handled by the AFTN services: Distress messages and distress traffic Urgency messages Flight safety message Meteorological messages Flight regularity messages Aeronautical administrative messages SNOWTAM, ASHTAM, NOTAM Class 1 distribution Reservation messages General aircraft operating agency messages Service messages. AFTN message format shall be as follows 11.2.1 Message Heading The start-of-message signal is consisting of the characters ZCZC. The transmission identification comprises of: 11.2.1.1 Circuit Identification Shall consist of three letters selected and assigned by the transmitting station The first letter is transmitting-terminal letter The second letter is receiving-terminal letter The third letter is channel-identification letter Where there is only one channel between the transmitting and receiving stations, channel letter A shall be assigned. If more than one channel is provided, the channels shall be identified as A, B, C, etc. in respective order.
PAGE: 8 11.2.1.2 Channel-Sequence Number 3-digit numbers from 001-000 (representing 1,000) shall be assigned sequentially by telecommunication stations to all messages transmitted directly from one station to another. A separate series of these numbers shall be assigned for each channel and a new series shall be started daily at 0000 UTC hours. Note: Example of the transmission identification standard BTG039- Indicates the 39th message of the day transmitted on Channel G of the circuit from Station B to Station T. 11.2.1.3 Priority The priority indicator shall consist of the appropriate 2-letter group assigned by the originator in accordance with the following: Message category Distress message, distress traffic and urgency messages Messages justifying the requirement for special priority handling Flight safety messages Meteorological messages Flight regularity messages Aeronautical administrative messages Reservation messages General aircraft operating agency messages Service messages Priority indicator SS DD FF GG GG GG GG KK as appropriate The order of priority for the transmission of messages in the AFTN network shall be as fallows Transmission priority Priority indicator 1 SS 2 DD FF 3 KK GG 11.2.1.4 Address The addressee indicator shall be comprised of the ICAO 4-letter location indicator of the place of destination followed immediately by the ICAO 3-letter designator identifying the organization (aeronautical authority, service or aircraft operating agency) addressed followed by the filler letter X. The originator of a message shall be permitted to use in place of the filler letter X, one letter representing a division or department of the organization addressed. That letter will facilitate the internal distribution of message within the organization. The addressee indicator shall be immediately preceded by SPACE. Note: Example of the addressee indicator VTBDZPZX: addressed to the ATS Reporting office served by the aeronautical fixed station located at the Bangkok International Airport (VTBD).
PAGE: 9 VTBDACJX: addressee indicator for the designated office of the aircraft operating agency, AC AVIATION, located at the Bangkok International Airport (VTBD), with internal routing instructions for delivery to the airlines Flight Dispatch Service office (W). 11.2.1.5 Origin The origin shall be comprised of: (a) Filing Time (b) Shall be comprised of the 6-digit date/time group indicating the date and time of filing the message for transmission in UTC. (c) Original Indicator Shall be composed in the same way as address group to show the location indicator of the place at which the message is originated. 11.2.1.6 Text The text of the message entered by the AFTN origin station shall not exceed 1,800 characters in length. 11.2.1.7 Message Ending The ending of a message shall comprise letter N, appearing 4 times in undivided sequence (NNNN). Note: Each of AFTN messages transmitted by the AFTN origin station shall not exceed 2,100 characters in length (i.e. 7 lines) including printing and non-printing characters in the message from and including the start-of-message signal (ZCZC) to and including the end-of-message signal (NNNN). 11.3 Mobile Communication 11.3.1 General Aeronautical mobile services can be made between aeronautical and aircraft stations or between aircraft stations themselves. The air-ground radio frequencies used shall be selected from: The band 131.475 MHz for regular VHF communication system. VHF communication systems are a short to medium range which keeps interference with distant stations at the same frequency to a minimum. However, it is not suitable if used for communications in international oceanic airspace due to the inherent line-of-sight limitations of the equipment. The band 2.8 to 22.0 MHz for Single sideband (SSB) HF communication system which permits voice communication over distances much farther than line-of- sight radio system of VHF. Therefore, HF system is generally used from aircraft to ground stations or other aircraft stations during any operation which is conducted in international oceanic airspace and also will be required to maintain a continuous listening watch and communication capability on the assigned HF frequencies. Although HF frequencies are designated by Air Traffic Control in each area, actual communication may be with general purpose communication facilities such as international flight service stations or Aeronautical Radio Incorporation (ARINC) or other operators. These facilities will be responsible for the relay of position
PAGE: 10 reports and other pertinent information between the aircraft and Air Traffic Control. In general, the English language should be used by international air services. The standards and recommended practices is set up in order to provide the means by which pilots and ground personnel communicate and understand with each other. The exchange of communications shall be concise and unambiguous' using standard radiotelephony phraseologies and spellings. These phraseologies and spellings prescribed in ICAO Annex 10 Volume II Chapter 5 and Manual of radiotelephony, Document 9432 shall be used in all situations. Speech transmitting techniques required by users will be as follows: Before transmitting, listen out on the frequency to be used to ensure that there will be no interference with a transmission from another station. Use a normal conversation tone, speak clearly and distinctly. Maintain an even rate of speech. When a message needs to be recorded, the speaking rate should be slightly slower to allow for the writing process. A slight pause before and after numbers will make them easier to understand. Maintain the speaking volume at a constant level. Be familiar with good microphone operating techniques such as maintain a constant distance from the microphone and suspend speech temporarily if it is necessary to turn the head away from the microphone, depress the transmit switch fully before speaking and do not release it until the message is completed in order to ensure that the entire message is transmitted. The transmission of long message should be interrupted momentarily from time to time to permit the transmitting operator to confirm that the frequency in use is clear and, if necessary, to permit the receiving operator to request repetition of parts not received. Avoid using hesitation sounds such as 'er'. Whenever the communication is established, the receiving operator shall acknowledge the receipt of the message. 11.3.2 Company Utility Telecommunication Channel (CUT) There is a general requirement from the Company's point of view for direct links between the pilot of an aircraft and Company in order to permit exchange of messages regarding importance for the safe, efficient and economical operation of aircraft. The available authority operating communication channels (General Purpose Stations), which are normally handling this type of air-ground communication on HF or VHF, cannot fulfil the requirement for direct links as the communication is relayed through a radio operator via teletype, telephone or other means. This will, in most cases, delay the exchange of messages between pilot and Company and the vital direct contact is missing. It is therefore considered necessary to arrange all facilities to handle this kind of communication through installation of Company Utility Channel (CUT) on VHF in Dispatch or Traffic-Offices at a number of AC AVIATION stations (131.475MHz). The CUT installation is an amplitude modulated radio telephone station designed for fixed frequency operation on the VHF band with various transmitter output, depending on local requirements and
PAGE: 11 conditions. 11.3.2.1 Utilization of the CUT The CUT must be used with sound judgment as misuse may easily reduce the originally intended value of this facility e.g. calls from the ground should be avoided during takeoff and landing, when the flight deck crew is most busy. The CUT can be utilized for a large variety of messages directly related to the ground handling or general operation of a flight, and advantage should be taken from this facility to speed up preparatory work which can support an efficient and smooth handling. Frequencies for Company VHF air-ground communications are assigned to the aircraft operating agencies by States and coordinated within IATA/ICAO to ensure best possible utilization of the narrow band allotted for this purpose. 11.3.2.2 Guard of the CUT The CUT installation provides coverage up to 50NM flying time from the airport. During this period, it is the responsibility of station managers to ensure that loudspeaker guard is maintained on the CUT channel in connection with each Company operation into and out of the airport. Flight deck crew is instructed to maintain continuous guard on the CUT when within coverage. However, should the crew not be guarding the CUT due to other duties on board, Air Traffic Control may be asked to advise the aircraft that the station wishes to communicate on the CUT. 11.3.2.3 Operational Control of Facilities The basic requirements for air-ground radio communications are a good command of the English language, ICAO radiotelephony phraseology as well as knowledge of the functions of the radio equipment used. The communication permissible over the air-ground CUT channel includes: FLIGHT OPERATIONS messages MAINTENANCE messages PASSENGER SERVICE messages RAMP SERVICE messages CABIN SERVICE messages. Aircraft dispatchers have the authority to originate and transmit to aircraft in flight information or advice pertaining to the safe conduct or the operational planning of the flight such as: Weather information Altimeter settings Runway conditions Holding recommendation Diversion recommendation When exercising this authority, the aircraft dispatcher shall avoid taking such an action that would conflict with the procedures established by Air Traffic Control, the Meteorological Service or the Communication
PAGE: 12 Service. He shall reveal the identity of messages originated by inserting "AC AVIATION OPERATION (station name)" either before or after the text, whichever appropriate. Messages from a Dispatch Office or information from an Air Traffic Service/ Meteorological Office to a flight shall be transmitted on the CUT channel verbatim as received. Assistant dispatchers also have the authority to transmit to aircraft in flight any or all of the following information if they are deemed to affect the planned operation of the flight in any way: Terminal and alternate weather Runway conditions at the terminal and its alternate NOTAM information regarding the serviceability of navigation aids at the terminal and its alternate Holding and/or diversion recommendations based on actual weather conditions and with due consideration to the traffic situations. 11.4 Long Range Company Operational Control Radio Service The purpose of this service is to provide direct voice communications between flight crews and their company control offices via HF SSB communications using 'phone patch' techniques primarily in the international environment. Aircraft will use the assigned frequencies from any location. However, the limiting factor being the actual propagation of the radio signals which may vary depending upon the frequency, time of day, latitude, local atmospheric noise level and sun spot activity. Messages category handled by the Station generally are 'Flight regularity' messages. Those messages include messages that require immediate action on the part of flight crews, aircraft operators, or agencies acting for aircraft operators for the efficient and expeditious utilization of aircraft to avoid serious delays or travel interruptions to passengers and/or cargo, or to avoid situations that could cause the aircraft operator to suffer significant economic penalties. Together, meteorological information is also obtained and passed to the aircraft on request. The main use made of the Station is for position reporting and giving advance warning of serviceability status. However, advice can also be passed to aircraft concerning civil/military disturbance, airspace closures, flight plan clearances etc. Note 1: Communications concerning air traffic control for international flights are considered 'Flight Safety' messages and are usually handled on the ICAO Major World Air Route Area (MWARA) High Frequency and VHF Enroute Radio Telephone Networks or VHF ATS facilities.