Aeronautical Fixed Telecommunication Network

From Wikipedia, the free encyclopedia

The Aeronautical Fixed Telecommunication Network (AFTN) is a worldwide system of aeronautical fixed circuits provided, as part of the aeronautical fixed service, for the exchange of messages and/or digital data between aeronautical fixed stations having the same or compatible communications characteristics. AFTN comprises aviation entities including: ANS (Air Navigation Services) providers, aviation service providers, airport authorities and government agencies, to name a few. It exchanges vital information for aircraft operations such as distress messages, urgency messages, flight safety messages, meteorological messages, flight regularity messages and aeronautical administrative messages.

1 Communications infrastructure
2 Station address format
3 Message content
4 Further reading

[edit] Communications infrastructure

Please help improve this section by expanding it.
Further information might be found on the talk page or at requests for expansion.

[edit] Station address format

AFTN addresses are 8 characters long. They consist of the 4-letter ICAO station code with a 4-letter facility code appended. Facility code ZTZX refers to Control Tower, ZPZX refers to ATS Reporting Office or "ARO" of a specific aerodrome and ZQZX refers to Area Control Center.

[edit] Message content

AFTN messages can be given a message priority to ensure best use of the system. The priority indicators and their meanings are shown in the following table:

Indicator	Content	Priority
SS	accidents	High (Mayday)
DD	very important notices or events	Urgency
GG	important events	Normal
FF	Flight messages (FPL, DLA, ARR etc.)	Normal
KK	other and company messages	Low

The AFTN system is backwards compatible with older transmission technology as many member states do not upgrade their AFTN centers fast enough. The message format betrays the extensive use of radioteletype links in the past. A typical message would look like:

ZCZC DFA05 12032006
DD RCTPZQZX
1209 VTBBZQZX

MESSAGE

NNNN

The ZCZC stands for start of message and is geared towards torn-tape stations where the Z and c characters will punch all five holes on the tapes providing a quick check to the operator that the tape-puncher is working correctly. The NNNN similar is a familiar one hole consecutive sequence which can be quickly identified as end of message by operators.

The message routing is easily automated by general purpose computers. Teletype communication with airline operators is sometimes maintained by having a connection to the IATA Type B messaging networks which use a 7 character address. The whole communications system is still rooted in the 'official' nature of radio teletypes.

The older tape stations (and perhaps newer ones) also included a bell that could be rung by using a set character code. The purpose of the bell was to allow the sender to alert the receiving operator of a high priority message such as an SS message. It was also possible to insert spacing between bell rings. With care and persistence, you could compose a musical tune to play to far distant stations. Jingle bells was a favourite. A particularly clever 'author' could combine the tune with an image such as a Christmas tree. The skill for this was often learnt on those long night watches when little traffic was in the air.

Each country within the network has it airports and aerodrome reporting location addresses beginning with a letter. For instance the letter K, is the first letter of the four letter ICAO address location within the United States. The first letter for a Canadian aerodrome, or airport address, begins with the letter C.

Other airport required reports are also transmitted through the AFTN, on daily and hourly intervals like flight plans, NOTAM's (notices to airmen), and AIRAD's (Airfield Advisories). For example, a message originated at New York's John F. Kennedy airport would be KJFK. Goose Bay Canada's airport originated messages would be identified as CYYR.