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AMHS Term – AMHS Aviation Terminal


The AMHSTerm is an ICAO SARPs compliant X.400 User Agent, which allows end users to connect to the AMHS to send and receive ATC messages. It has been specifically designed with the needs of ATS operators in mind, providing a full set of ICAO 4444 forms. As an X.400 User Agent, it can also be used to send and receive free text messages, including attachments and multiple body parts. Running under many operating systems, the AMHS Terminal presents a consistent Graphical User Interface design.

General Features

  • Use of advance features of the X.400 P7 protocol, such as auto alerts and Message Store filters.
  • Local message caching to prevent fetching repeated messages and to avoid loading the Message Store
  • HTML support in X.400
  • Contact manager with tags for favourite users, access to the ATN X.500 Directory for address browsing and synchronization, local user groups, AFTN/AMHS Address Conversion and many other features
  • Also supports POP, IMAP and SMTP, with SSL and STARTTLS
  • Supports multiple accounts, of any type, at the same time, so it’s ideal for environments where computers are shared by several users.
  • Sorting of messages in a folder ( Subject, Sender, Recipient and size)
  • Drag and drop of messages to folders
  • Multi-language interface (English and Spanish by default, more can be added)
  • Filtering of messages based on search criteria
  • Support for sending X.400 Probes
  • Support for SSL over X.400 P7 (ITOTS), to connect directly to, for example, Business Mail X.400 Mailbox.
  • Automatically updates the Filing Time on content changes
  • Support for saving and editing draft messages, which can be used as templates for new messages
  • Built-in Log Viewer, where all the activity of the program can be reviewed
  • Configurable date formats
  • Detailed message properties analyser for X.400 messages


Aviation – Specific Features

  • Creation of ICAO 4444 messages using familiar forms for: FPL, SPL, ARR, DEP, CNL, DLA, RQM, RQS, RQP, CHG, CPL, EST, CND, ACP, ALR, RCF, SPL.
  • The forms are compatible with the new FPL2012 format
  • Creation of ICAO AIS messages using familiar forms for: NOTAM, SNOWTAM, SNOWTAM GRF and ASHTAM. Note that SNOWTAM GRF is the new Global Reporting Format that will be used on 4th November 2021
  • Flexible AFTN ↔ AMHS address conversion, using either an ICAO compliant X.500 ATN Directory, or the AMC Tables with conversion information.
  • Supports both ICAO XF and CAAS addressing schemes
  • Support of the generation and reception of messages in both Basic Encoding and Extended Encoding
  • Supports all the Extended ATS Message Handling Service functional groups – Basic + IHE + DIR + FTBP + SEC.
  • [FTBP] Supports the use of File Transfer Body parts, to handle message attachments. This can be used, for example, to send and receive METAR, SPECI and TAF messages using the BUFR format.
  • [IHE] Support of the generation and reception of messages in with IPM Heading Extensions
  • [DIR] Supports the use of Directory to access the X.500 ATN Directory to search for users and determine their capabilities, for example, if they support IHE or FTBP for AFTN ↔ AMHS address conversion
  • [SEC] Support for the SEC functional group
  • Digital Signatures to verify the originator of a message
  • MOAC (Message Origin Authentication and Content Integrity) to verify that the message has not been corrupted or tampered with in transit.
  • Message Sequence Integrity, to alert the user of missing messages.


The connection to the AMHS Switch can be achieved through the use of the standard Internet Protocol (IP) sockets, or by using the full OSI stack to connect to an ATN Router. Both IPv4 and IPv6 are supported. The messaging protocols that are supported are: X.400 P3, X.400 P7, AFTN, SMTP, IMAP and POP.The directory protocols that are supported are: X.500 DAP and LDAP


The AMHSTerm runs on Windows (all versions from Windows 2008 onwards, including Windows Server 2012, Server 2016, Server 2019 and Windows 10), Linux (RedHat and CentOS 7 and 8, Ubuntu, and other similar Open Source operating systems)


  • ICAO Doc 9880
  • ICAO Doc 4444
  • Extended ATS Message Handing Services
  • ATS Messaging Management Manual (Eur Doc 021)
  • EUR ATS Messaging Management Manual, version 9.0 (Eur Doc 020)
  • RFC 2126, RFC 4511