Flight plans, meteorological reports and other operational messages have travelled over the Aeronautical Fixed Telecommunication Network (AFTN) for decades. Developed in the teleprinter era, AFTN created a standard way for aviation organisations around the world to address, route and exchange essential information.
That network is now being progressively supplemented and replaced by the more capable ATS Message Handling System (AMHS). For UK airports, however, migration is not simply a matter of switching one connection off and another on. NATS currently provides Aeronautical Fixed Service data through both AFTN and AMHS, making interoperability particularly important while existing airport systems and external networks migrate at different rates.
So, What Changes When You Move From AFTN To AMHS?
The biggest difference is the way information can be carried.
AFTN was designed to accommodate character-based messaging, and although the communications technology underneath it has evolved considerably since the 1950s, the AFTN message format is still highly structured and text orientated. ICAO Annex 10 defines a strict AFTN structure comprising a heading, address, origin, message text and ending. The address includes the message priority and eight-letter addressee indicator, while the origin identifies when and where the message was filed.
AMHS moves ATS messaging onto a much more capable architecture. Defined within ICAO Doc 9880, it uses the X.400 messaging standards and can operate over IP-based network infrastructure. Extended AMHS can also carry binary information and attachments, opening the way to data that cannot be accommodated within traditional AFTN character messages.
This makes AMHS much better suited to the increasingly data-rich information aviation systems need to exchange.
Why Does The AFTN Message Format Still Matter?
Moving to AMHS does not immediately remove AFTN from your airport.
An AFTN address uses an eight-letter addressee indicator, while AMHS uses X.400 originator/recipient addresses. During migration, messages may therefore need to cross between systems using completely different addressing structures.
That is the job of an AFTN/AMHS gateway.
When an AFTN message enters an AMHS network, the gateway converts its address into the appropriate X.400 address and maps information including the originator, priority, filing time and message text into the AMHS message. Traffic travelling in the opposite direction has to be converted back into a valid AFTN message.
Converting an AFTN address into AMHS means mapping it to the correct destination within a different addressing structure, not simply reformatting the same characters. Gateways use defined mapping information, such as management-domain, addressing and user tables, to determine where the eight-character AFTN address belongs within AMHS. EUROCONTROL’s ATS Messaging Management Centre coordinates this address and routing information across the European network to support the process.
What Your Airport Should Check Before Migrating
Before migrating, start with the systems that currently consume or generate AFTN messages.
For example, your flight data processing, meteorological, NOTAM or other operational applications may still expect an AFTN interface even when your external connection moves to AMHS. Replacing every application simply to accommodate X.400 messaging may neither be necessary nor desirable.
A connector can instead allow an existing AFTN-based application to communicate through AMHS while handling the message and address conversion between the two environments. Our AMHSConnect was developed specifically for this type of requirement, including connections from systems such as MET and flight data processing applications.
You also need to establish which AMHS service level and message capabilities your connected systems support, how addresses will be maintained and how message routing, logging and failure handling will work once the new connection is live.
Make The Move From AFTN To AMHS
At Copperchase, we supply AFTN and AMHS messaging systems together with AFTN/AMHS gateways that allow the two environments to operate together during migration. Please contact our team today to find out more.
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