Acronyms and Glossary
It has been rumored that the introduction of datalink into the airline industry originated as part of a contest to see how many acronyms could be developed around a specific technology. Whether this is true or not, the industry is at the point where acronyms are now nested within acronyms. For example, AOA is an acronym for ACARS Over AVLC, where AVLC itself is an acronym for Aviation VHF Link Control and VHF is also an acronym for Very High Frequency.
- ACARS
- Aircraft Communications Addressing and Reporting System
- ACMS
- Aircraft Condition Monitoring System
- AMS
- ACARS Message Security, as specified in ARINC 823
- AOA
- ACARS Over AVLC. With the introduction of VDL Mode 2, the ACARS protocols were modified to take advantage of the higher data rate made possible by Mode 2. AOA is an interim step in replacing the ACARS protocols with ATN protocols.
- ATN
- Aeronautical Telecommunications Network. As air traffic increases, ACARS will no longer have the capacity or flexibility to handle the large amount of datalink communications. ATN is planned to replace ACARS in the future and will provide services such as authentication, security, and a true internetworking architecture. Europe is leading the US in the implementation of ATN.
- AVLC
- Aviation VHF Link Control. A particular protocol used for aeronautical datalink communications.
- CDU
- Control Display Unit
- CMF
- Communications Management Function. The software that runs in a CMU, and sometimes as a software partition in an integrated avionics computer.
- CMU
- Communications Management Unit. Successor to the MU, the CMU performs similar datalink routing functions, but has additional capacity to support more functions. CMU standards are defined in ARINC Characteristic 758.
- FDAMS
- Flight Data Acquisition and Management System
- FMS
- Flight Management System. FMS standards are defined in ARINC Characteristic 702 and 702A.
- HFDL
- High Frequency Data Link is an ACARS communications media used to exchange data such as Airline Operational Control (AOC) messages, Controller Pilot Data Link Communication (CPDLC) messages and Automatic Dependent Surveillance (ADS) messages between aircraft end-systems and corresponding ground-based HFDL ground stations.
- HF
- High Frequency. A portion of the RF spectrum.
- LRU
- Line Replaceable Unit. An avionics "black box" that can be replaced on the flight line, without downing the aircraft for maintenance.
- MCDU
- Multifunction Control Display Unit. A text-only device that displays messages to the aircrew and accepts crew input on an integrated keyboard. MCDU standards are defined in ARINC Characteristic 739. MCDUs have seven input ports and can be used with seven different systems, such as CMU or FMS. Each system connected to an MCDU generates its own display pages and accepts keyboard input, when it is selected as the system controlling the MCDU.
- MIDU
- Multi-Input Interactive Display Unit (often used as a third cockpit CDU).
- MU
- Management Unit. Often referred to as the ACARS MU, this is an avionics LRU that routes datalink messages to and from the ground.
- OOOI
- Shorthand for the basic flight phases—Out of the gate, Off the ground, On the ground, In the gate.
- POA
- Plain Old ACARS. Refers to the set of ACARS communications protocols in effect before the introduction of VDL Mode 2. The term is derived from POTS (Plain old telephone service) that refers to the wired analog telephone network.
- SATCOM
- Satellite Communications. Airborne SATCOM equipment includes a satellite data unit, medium to high power amplifier, and an antenna, possibly with a steerable beam. A typical SATCOM installation can support a datalink channel as well as one or more voice channels.
- VDL
- VHF Data Link
- VHF
- Very High Frequency. A portion of the RF spectrum, defined as 30 MHz to 300 MHz.
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