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Aircraft Communications Addressing and Reporting System (ACARS) is a digital datalink system fortransmission of short, relatively simple messages between aircraft and ground stations via radio or satellite.The protocol, which was designed by Aeronautical Radio, Incorporated (ARINC) to replace their very highfrequency (VHF) voice service and deployed in 1978,[1] uses telex formats. The IT company SITA lateraugmented their worldwide ground data network by adding radio stations to provide ACARS service. Overthe next 20 years, ACARS will be superseded by the Aeronautical Telecommunications Network (ATN)protocol for Air Traffic Control communications and by the Internet Protocol for airline communications.

Contents

[hide]

1 History of ACARS1.1 Introduction of ACARS systems1.2 OOOI events1.3 Flight management system interface1.4 Maintenance data download1.5 Interactive crew interface

2 How it works2.1 VHF subnetwork2.2 Satellite communication and HF subnetworks2.3 Datalink message types

3 Example transmissions3.1 Departure delay downlink3.2 Weather report uplink3.3 Flight data acquisition and management system message downlink

4 Aircraft equipment5 Datalink service provider6 Ground end system7 ARINC specifications8 Acronyms and glossary9 GIS and data discovery10 See also11 References

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12 External links

History of ACARS[edit]

Prior to the introduction of datalink, all communication between the aircraft (i.e., the flight crew) andpersonnel on the ground was performed using voice communication. This communication used either VHFor HF voice radios, which was further augmented with satellite communication in the early 1990s. In manycases, the voice-relayed information involved dedicated radio operators and digital messages sent to anairline teletype system or successor systems.

Introduction of ACARS systems[edit]

In an effort to reduce crew workload and improve data integrity, the engineering department atAeronautical Radio, Inc (ARINC), introduced the ACARS system in July 1978, although a few experimentalACARS systems had been introduced earlier. Already the first day of operations saw about 4,000transactions, but ACARS did not experience widespread use by the major airliners until the 1980s.

The original ARINC development team was headed by Crawford Lane and included Betty Peck, aprogrammer, and Ralf Emory, an engineer. The terrestrial central site, a pair of Honeywell Level 6minicomputers, and AFEPS (Arinc Front End Processor System) software were developed by asubcontractor, Eno Compton of ECOM, Inc.

Although the term ACARS is often understood as the data link avionics line-replaceable unit installed onaircraft, the term actually refers to a complete air and ground system. The original expansion of theabbreviation was "Arinc Communications Addressing and Reporting System".[2] Later, it was changed to"Airline Communications, Addressing and Reporting System".

On the aircraft, the ACARS system was made up of an avionics computer called an ACARS ManagementUnit and a Control Display Unit. The management unit was designed to send and receive digital messagesfrom the ground using existing VHF radios.

On the ground, the ACARS system was made up of a network of radio transceivers managed by a centralsite computer called AFEPS (Arinc Front End Processor System), which received (or transmitted) the datalinkmessages as well as routed them to various airlines on the network.

The initial ACARS systems were designed to ARINC Characteristic 597. This was later upgraded in the late1980s by the publication of ARINC Characteristic 724. ARINC 724 is intended for aircraft installed withavionics supporting digital data bus interfaces. ARINC 724 was updated to the current standard ARINCCharacteristic 724B, which is the predominate standard for all digital aircraft.[clarification needed] With theintroduction of ARINC 724B, the ACARS management units were also coupled with industry standardprotocols for operation with flight management system MCDUs (ARINC 739), and printers (ARINC 740 andARINC 744). The ACARS management unit has expanded to serve broader needs using a communicationsmanagement unit defined by ARINC Characteristic 758. Today, new aircraft designs integratecommunications management unit functions in integrated modular avionics (IMA). ARINC Standards areprepared by the Airlines Electronic Engineering Committee.

OOOI events[edit]

One of the initial applications for ACARS was to automatically detect and report changes to the major flightphases (Out of the gate, Off the ground, On the ground, and Into the gate), referred to in the industry asOOOI.[3] These OOOI events are determined by algorithms that use aircraft sensors (such as doors, parkingbrake and strut switch sensors) as inputs. At the start of each flight phase, a digital message is transmittedto the ground containing the flight phase, the time at which it occurres, and other related information such

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as the amount of fuel on board or the flight origin and destination. These messages are used to track thestatus of aircraft and crews.

Flight management system interface[edit]

In addition to detecting events on the aircraft and sending messages automatically to the ground, initialsystems were expanded to support new interfaces with other on-board avionics. During the late 1980s andearly 1990s, a datalink interface was introduced between the ACARS management units and flightmanagement systems. This interface enables flight plans and weather information to be sent from theground to the ACARS management unit, for forwarding to the flight management system. This feature givesthe airline the capability to update flight management systems while in flight, and allows the flight crew toevaluate new weather conditions or alternative flight plans.

Maintenance data download[edit]

The introduction of the interface in the early 1990s between the flight data acquisition and managementsystem, the aircraft condition monitoring system and the ACARS management unit resulted in wideracceptance of datalinks on the part of airlines. The flight data acquisition and management system and theaircraft condition monitoring system systems which analyze engine aircraft and operational performanceconditions now provide performance data to the airlines on the ground in real time using the ACARSnetwork. This reduces the need for airline personnel to go to the aircraft to off-load the data from thesesystems. These systems are capable of identifying abnormal flight conditions and automatically sendingreal-time messages to an airline. Detailed engine reports can also be transmitted to the ground via ACARS.The airlines use these reports to automate engine trending activities. This capability enables airlines tomonitor their engine performance more accurately and identify and plan their repair and maintenanceactivities more rapidly.

In addition to the interfaces for the flight management system and the flight data acquisition andmanagement system, the industry started to upgrade the on-board maintenance computers in the 1990s tosupport the transmission of maintenance-related information in real-time through ACARS. This enabledairline maintenance personnel to receive real-time data associated with maintenance faults on the aircraft.When coupled with the flight data acquisition and management system data, airline maintenance personnelcan start planning repair and maintenance activities while the aircraft is still in flight.

Interactive crew interface[edit]

All of the processing described above is performed automatically by the ACARS management unit and otherassociated avionics systems, without flight crew intervention. As part of the growth of ACARS functionality,the ACARS management units also interface directly with a control display unit located in the cockpit. Thiscontrol display unit, often referred to as a multifunction control display unit or a multi-input interactivedisplay unit, provides the flight crew with the ability to send and receive messages similar to today’s email.To facilitate this communication, the airlines in partnership with their ACARS vendor defines multifunctioncontrol display unit screens that could be presented to the flight crew and enable them to perform specificfunctions. This feature provides the flight crew flexibility as to the types of information requested from theground and the types of reports sent to the ground.

As an example, the flight crew could pull up a multifunction control display unit screen that allowed them tosend to the ground a request for various types of weather information. After the desired locations and typeof weather information are entered, ACARS transmits this information to the ground. In response to thisrequest message, ground computers send the requested weather information back to the ACARSmanagement unit for subsequent display and/or printing.

Airlines began adding new messages to support new applications (weather, winds, clearances, connectingflights, etc.) and ACARS systems were customized to support airline-unique applications and unique groundcomputer requirements. This resulted in each airline having its own unique ACARS application operating on

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its aircraft. Some airlines have more than 75 multifunction control display unit screens for their flight crews,where other may have only a dozen different screens. In addition, since ground computers differ for eachairline, the contents and formats of the messages sent by an ACARS management unit differ accordingly.

In the wake of the crash of Air France Flight 447, there has been discussion about making ACARS an"online-black-box."[4] If such a system were in place, it would avoid the loss of data due to: (1) black-boxdestruction, and (2) inability to locate the black-box following loss of the aircraft. However, due to highbandwidth requirements, the cost would be excessive and there have in fact been very few incidents wherethe black boxes were not recoverable.

How it works[edit]

An on board person or system can create a message and send it via ACARS to a system or user on theground, and vice versa. Messages may be sent either automatically or manually.

VHF subnetwork[edit]

A network of VHF ground radio stations ensures that aircraft can communicate with ground end systems inreal-time from practically anywhere in the world. VHF communication is Line-of-sight propagation andprovides communication with ground-based transceivers (often referred to as remote ground stations). Thetypical range depends on altitude, with a 200-mile transmission range common at high altitudes. Thus VHFcommunication is only applicable over land masses which have a VHF ground network installed.

Sample ACARS VHF transmission

The sound of an ACARS VHF transmission made on 130.025 MHz, recorded at Petaluma, Californiaon 15 August 2006

Problems playing this file? See media help.

A typical ACARS VHF transmission.Mode A

Aircraft B-18722Ack NAK

Block id 2Flight CI5118Label B9

Msg No. L05AMessage /KLAX.TI2/024KLAXA91A1

Satellite communication and HF subnetworks[edit]

Satellite communication can provide worldwide coverage. Depending on the satellite system in use,coverage may be limited or absent at high latitudes (such as needed for flights over the poles). HF datalinkis a relatively new network whose installation began in 1995 and was completed in 2001. Aircraft with HFor global satellite communication datalinks can fly polar routes and maintain communication with ground-based systems (ATC centers and airline operation centers). ARINC is the only service provider for HFdatalink.

Datalink message types[edit]

ACARS messages may be of three types:

0:00 MENU

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Air Traffic ControlAeronautical Operational ControlAirline Administrative Control

Air traffic control messages are used to communicate between the aircraft and air traffic control. Thesemessages are defined in ARINC Standard 623. Air traffic control messages are used by aircraft crew torequest clearances and by ground controllers to provide those clearances.

Aeronautical operational control and airline administrative control messages are used to communicatebetween the aircraft and its base. These messages are either standardized according to ARINC Standard633 or defined by the users, but in the latter case they must meet at least the guidelines of ARINCStandard 618. Various types of messages are possible, for example, relating to fuel consumption, engineperformance data, aircraft position, in addition to free text.

Example transmissions[edit]

Departure delay downlink[edit]

A pilot wants to inform his flight operations department that departure has been delayed by air trafficcontrol. The pilot loads from the communications management unit a multifunction control display unitscreen that allows him to enter the expected length of and reason for the delay. After entering theinformation on the multifunction control display unit, he depresses on it a “SEND” key. The control displayunit detects that the SEND key was pushed and generates a digital message containing the delayinformation. This message may include such information as aircraft registration number, the origination anddestination airport codes, the current estimated time of arrival before the delay, and the current expectedduration of the delay. The communications management unit then sends the message to an existing radio(HF, satellite communication or VHF, with the selection of the radio based on special logic contained withinthe communications management unit). For a message to be sent over the VHF network, the radiotransmits the VHF signals containing the delay message, which is then received by a VHF remote groundstation.

Most ACARS messages are only 100 to 200 characters in length. Such messages are made up of a one-block transmission from (or to) the aircraft. One ACARS block is constrained to be no more than 220characters within the body of the message. For downlink messages which are longer than 220 characters,the ACARS unit splits the message into multiple blocks, transmitting each block to the remote groundstation (there is a constraint that no message may be made up of more than 16 blocks). The remoteground station collects each block of such multi-block messages until the complete message is receivedbefore processing and routing the message. ACARS also contains protocols to support a retry of failedmessages or retransmission of messages whenever the service provider changes.

Once the remote ground station receives the complete message, it forwards the message to the datalinkservice provider's main computer system. The datalink service provider's ground network uses landlines tolink the remote ground station to the datalink service provider. The datalink service provider usesinformation contained in its routing table to forward the message to the airlines or other destinations. Thistable is maintained by the datalink service provider and identifies each aircraft (by tail number) and thetypes of messages that it can process. (Each airline must tell its service provider(s) what messages andmessage labels their ACARS systems will send, and, for each message, where they want the serviceprovider to route the message. The service provider then updates its routing tables based on thisinformation.) Each type of message sent by the communications management unit has a specific messagelabel, which is contained in the header information of the message. Using the label contained in themessage, the datalink service provider looks up the message in the table and forwards it to the airline’scomputer system. which then processes the message.

This processing performed by an airline may include reformatting the message, populating databases forlater analysis, or forwarding the message to other departments, such as flight operations, maintenance,

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engineering, finance, or other organizations within an airline. In the example of a delay message, it may berouted via the airline’s network to both their operations department as well as to a facility at the aircraft’sdestination, notifying them of a potential late arrival.

The elapsed transmission time from the moment the flight crew presses the send key to the moment it isprocessed by an airline’s computer system varies, but is generally on the order of 6 to 15 seconds. Themessages that are sent to the ground from the communications management unit are referred to asdownlink messages.

Weather report uplink[edit]

For a message to be transmitted to the aircraft (referred to as an uplink message), the process is nearly amirror image of how a downlink is sent from the aircraft. For example, in response to an ACARS downlinkmessage requesting weather information, a weather report is constructed by the airline’s computer system.The message contains the aircraft registration number in the header of the message, with the body of themessage containing the actual weather information. This message is sent to the datalink service provider'smain computer system.

The datalink service provider transmits the message over its ground network to a VHF remote groundstation in the vicinity of the aircraft. The remote ground station broadcasts the message over the VHF. Onreceiving the VHF signal, the onboard VHF radio passes the message to the communications management(with the internal modem transforming the signal into a digital message). The communications managementvalidates the aircraft registration number and processes the message.

The processing performed on the uplink message by the communications management depends on thespecific airline requirements. In general, an uplink is either forwarded to another avionics computer, such asan FMS or FDAMS, or is processed by the communications management. For messages destined for thecommunications management (such as a weather report uplink), the flight crew refers to a specificmultifunction control display unit screen that contains a list of all received uplink messages. The flight crewthen selects the weather message for viewing on the multifunction control display unit. The ACARS unit mayalso print the message on the cockpit printer (either automatically upon receiving the message or inresponse to the flight crew's pressing a PRINT prompt on the MCDU screen).

Flight data acquisition and management system message downlink[edit]

Messages are sent to the ground from other on-board systems in a manner similar to the delay messageexample discussed above. As an example, a flight data acquisition and management system messagesystem may have a series of active algorithms monitoring engine exceedance conditions during flight (suchas checking whether engine vibration or oil temperature exceeds normal operating conditions). Upondetecting such an event, the Flight data acquisition and management system's message systemautomatically creates an engine exceedance condition message, with applicable data contained within thebody of the message. The message is forwarded to the communications management unit using what isreferred to as ARINC 619 data protocols. The communications management unit then transmits themessage to the ground. In this case, the service provider's routing table for an engine exceedance messageis typically defined to have the message routed directly to an airline’s maintenance department. Thisenables airline maintenance personnel to be notified of a potential problem in real time.

There are three major components to the ACARS datalink system:

Aircraft equipmentService providerGround processing system

Aircraft equipment[edit]

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The heart of the datalink system on board the aircraft is the ACARS management unit. The older version ofthe management unit is defined in ARINC Characteristic 724B. Newer versions are referred to as thecommunications management unit and are defined in ARINC Characteristic 758.

Aircraft equipment consists of airborne end systems and a router. End systems are the source of ACARSdownlinks and the destination for uplinks. The management unit/communications management unit is therouter. Its function is to route a downlink by means of the most efficient air-ground subnetwork. In manycases, the management unit/communications management unit also acts as an end system for aeronauticaloperational control messages.

Typical airborne end systems are the flight management system, datalink printer, maintenance computer,and cabin terminal. Typical datalink functions are:

Flight management system - sends flight plan change requests, position reports, etc. Receivesclearances and controller instructions.Printer - as an end system, can be addressed from the ground to automatically print an uplinkmessage.Maintenance computer - downlinks diagnostic messages. In advanced systems, in-flighttroubleshooting can be conducted by technicians on the ground by using datalink messages tocommand diagnostic routines in the maintenance computer and analyzing downlinked results.Cabin terminal - Often used by flight attendants to communicate special passenger needs, gatechanges due to delays, catering, etc.

ACARS messages are transmitted over one of three air-ground subnetworks.

VHF is the most commonly used and least expensive. Transmission is line-of-sight so VHF is notavailable over the oceans or other vast expansions of uninhabited surface, such as the Amazon Basin.Satellite communication is a fairly expensive service that provides (near) worldwide coverage. TheInmarsat satellite network does not cover the polar regions. However Iridium became usable forACARS transport in 2007 and provides excellent coverage in the polar regions.

HF is a more recently established subnetwork. Its purpose is to provide coverage in the polar regionswhere Inmarsat coverage is unreliable.

The router function built into the management unit/communications management unit determines whichsubnetwork to use when routing a message from the aircraft to the ground. The airline operator provides arouting table that the communications management unit uses to select the best subnetwork.

Datalink service provider[edit]

The role of the datalink service provider is to deliver a message from the aircraft to the ground end system,and vice versa.

Because the ACARS network is modeled after the point-to-point telex network, all messages come to acentral processing location. The datalink service provider routes the message to the appropriate end systemusing its network of land lines and ground stations. Before the days of computers, messages came to thecentral processing location and were punched on paper tape. The tape was then physically carried to themachine connected to the intended destination. Today, the routing function is done by computer, but themodel remains the same.

There are currently two primary service providers of ground networks in the world (ARINC and SITA),although specific countries have implemented their own network with the help of either ARINC or SITA.ARINC operates a worldwide network and has also assisted the Civil Aviation Administration of China, aswell as Thailand and South America with the installation of VHF networks. SITA has operated the network inEurope, Middle East, South America and Asia for many years. They have also recently started a network inthe USA to compete with ARINC.

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Until recently, each area of the world was supported by a single service provider. This is changing, and bothARINC and SITA are competing and installing networks that cover the same regions.

Ground end system[edit]

The ground end system is the destination for downlinks and the source of uplinks. Generally, ground endsystems are either government agencies such as the Civil Aeronautics Administration or the Federal AviationAdministration in the United States, an airline operations headquarters, or, in the case of small airlines orgeneral aviation consumers, a subscription based solution. Civil Aeronautics Administration end systemsprovide air traffic services such as clearances. Airline and general aviation operations provide informationnecessary for operating the airline or flight department efficiently, such as gate assignments, maintenance,and passenger needs. In the early history of ACARS most airlines created their own host systems formanaging their ACARS messages. Commercial off-the-shelf products are now widely available to managethe ground hosting.

ARINC specifications[edit]

Much of the processing performed by the communications management unit as well as basic requirementsof the hardware are defined by ARINC specifications. The following is a list of the major ARINCspecifications that define standards that govern many aspects of ACARS systems:

ARINC documents and their specifications

ARINC607

Design Guidance for Avionics Equipment. Includes definition of the aircraft personality modulerequired for ARINC 758 communications management unit installation.

ARINC429

Specification for receiving and broadcasting ARINC 429 broadcast data (data transfer betweenavionics line replaceable units). ARINC 429 is the one-way communication data bus (one data buspair to transmit data and another data bus pair to receive data).

ARINC618

Defines the air/ground protocols for communicating between the ACARS/communicationsmanagement unit and VHF ground systems. Also defines the format of the ACARS messages sentby the ACARS/communications management unit as well as received by the ACARS communicationsmanagement unit. The format of this message is called a Type A message. This characteristic hasbeen updated to define the future VDL Mode 2 ACARS over aviation VHF link control operation.

ARINC619

Defines the protocols for the ACARS/communications management unit to transfer data filebetween other avionics in the aircraft. ARINC 619 covers file protocols that are used to interfacewith the flight management system, flight data acquisition and management system, the cabinterminal, maintenance computers, satellite communication systems and HF voice data radios.

ARINC620

Defines ground-to-ground communication protocols. This includes the format of messages routedbetween a service provider and an airline or other ground system. This is referred to as a Type Bmessage (the air/ground Type A message is reformatted to a Type B message for groundtransmissions).

ARINC622

Describes the processing associated with sending air traffic control application messages overtoday’s ACARS links (including ARINC 623 ATC messages).

ARINC623

This characteristic identifies air-traffic-control-related messages that can be generated or receivedby an ACARS management unit/communications management unit system (does not include FANS-1 or FANS-A messages that are processed by the flight management system).

ARINC629

Specification for a bi-directional data bus for sending and receiving data between multiple avionicsline replacement units. The specification was initially developed for use on Boeing 777 commercialairplanes, but was published as an ARINC industry standard in 1999.

ARINC631

Specification for VHF Data Link Mode 2. This specification provides general and specific designguidance for the development and installation of the protocols needed to exchange bit-orienteddata across an air-ground VHF Digital Link in an open system interconnection environment.

ARINC

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724B Specification for an ACARS management unit for ARINC 724B wiring.

ARINC739 Specification for interfacing with multi-purpose cockpit display units.

ARINC740 Specification for interfacing to cockpit printers.

ARINC744

ARINC758

Specification for a communications management unit relative to ARINC 758 wiring. Thisspecification identifies various levels of functionality, these in turn defining future growth phasesfor the communications management unit. Initial communications management unit systems whichperform today’s ACARS functions are classified as Level OA.

ARINC823

Two-part specification that defines a security framework for protecting ACARS datalink messagesexchanged between aircraft and ground systems. Security services include confidentiality, dataintegrity and message authentication. Part 1, ACARS message security, specifies the securityprotocol, and Part 2, key management, specifies life-cycle management of the cryptographic keysnecessary for secure and proper operation of the ACARS message security system.

Acronyms and glossary[edit]

There has been rumour that the introduction of datalink into the airline industry originated as part of acontest to see how many acronyms could be developed around a specific technology. Whether this is trueor not, the industry is at the point where acronyms are now nested within acronyms. For example, AOA isan acronym for ACARS Over AVLC, where AVLC itself is an acronym for Aviation VHF Link Control andVHF 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 takeadvantage of the higher data rate made possible by Mode 2. AOA is an interim step in replacing theACARS protocols with ATN protocols.

ATN Aeronautical Telecommunications Network. As air traffic increases, ACARS will no longer have thecapacity or flexibility to handle the large number of datalink communications. ATN is planned toreplace ACARS in the future and will provide services such as authentication, security, and a trueinternetworking 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 asoftware partition in an integrated avionics computer.

CMU Communications Management Unit. Successor to the MU, the CMU performs similar datalink routingfunctions, but has additional capacity to support more functions. CMU standards are defined in ARINCCharacteristic 758.

FDAMS Flight Data Acquisition and Management System

FMS

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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 AirlineOperational Control (AOC) messages, Controller Pilot Data Link Communication (CPDLC) messages andAutomatic Dependent Surveillance (ADS) messages between aircraft end-systems and correspondingground-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 downingthe aircraft for maintenance.

MCDU Multifunction Control Display Unit. A text-only device that displays messages to the aircrew andaccepts crew input on an integrated keyboard. MCDU standards are defined in ARINC Characteristic739. MCDUs have seven input ports and can be used with seven different systems, such as CMU orFMS. Each system connected to an MCDU generates its own display pages and accepts keyboardinput, 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 datalinkmessages 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 theintroduction of VDL Mode 2. The term is derived from POTS (Plain old telephone service) that refersto the wired analog telephone network.

SATCOM Satellite Communications. Airborne SATCOM equipment includes a satellite data unit, medium to highpower amplifier, and an antenna, possibly with a steerable beam. A typical SATCOM installation cansupport 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.

GIS and data discovery[edit]

In 2002, ACARS was added to the NOAA Observing System Architecture. NOSA provides near realtime WMS maps and an ID search from the NOSA homepage.

See also[edit]

Aeronautical Telecommunication Network (ATN)Future Air Navigation System (FANS)Acronyms and abbreviations in avionicsSELCAL

References[edit]

1. ^ Carlsson, Barbara (October 2002),"GLOBALink/VHF: The Future Is Now", TheGlobal Link: 4, retrieved 2007-01-24

3. ^http://aspmhelp.faa.gov/index.php/OOOI_Data

4. ^ Online-Black-Box soll Crashs schneller

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2. ^http://www.arinc.com/downloads/product_collat

aufklären. (German) Spiegel-Online. June 6,2009. Accessed on: June 6, 2009.

External links[edit]

ARINC, inventors of ACARSacarsd, free ACARS decoder software for Linux/WindowsACARS on NOSAARINC Standards Document List, list and describe the ARINC standards

[show]

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vte

Earth-based meteorological observation systems and weather stations[show]

vte

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