AMHS is a message handling system, which allows the exchange of ATS (Air Traffic Services) messages among users. AMHS has been conceived to improve the existing worldwide methodology known as AFTN, by using an email-like concept, where messages can convey both text and attachments. AMHS is based on ITU-T X.400/X.500 protocols.
AMHS systems basically consist of a message switching node (MTA – Message Transfer Agent) and a number of user positions (UA – User Agents). These latter can receive/send messages related to air traffic control in Basic and Extended Encoding Mode. In Basic Mode, messages do not include attachments and can be sent to any other AMHS or AFTN terminal (through a gateway), while in Extended Mode messages may include attachments and will only be understandable by AMHS end users.
AMHS Terminals can be used as stand-alone machines or can be seen as Web Servers providing other operative positions the possibility to connect via an ordinary client Web browser and to access AMHS functionalities. Through this connection, operators may read received messages and prepare messages to be sent; they may also access the repository of received/sent messages and make queries.
AMHS Terminals can also be interfaced, via LAN or RS232 lines, to local AFTN systems that may therefore be transparently connected to the AMHS network to reach remote users. This AMHS-AFTN gateway feature, in particular, allows local METEO and FDP systems to bidirectionally send/receive messages to/from the AMHS network without modifying their current connection mode that remains AFTN.