ACARS (Aircraft Communication Addressing & Reporting System)

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Aircraft Communication Addressing & Reporting System (ACARS)

ACARS (Aircraft Communication Addressing & Reporting System) is  two way communication link between an Aircraft in flight and the Airline main ground facilities. Data is collected from the aircraft by digital sensors and is transmitted to  the  ground  facilities.  Replies  sent from  the  ground stations may  be printed out so the appropriate  flight  crew  can have a hard copy of the response. 

How ACARS work?

ACARS (Aircraft Communication Addressing and Reporting System) is a digital data transfer system between an aircraft and ground station that works in the VHF frequency range from 129 MHz to 137 MHz. ACARS allows aircraft operators to share data with their aircraft without the need for human involvement. This allows an airline to connect with its fleet of aeroplanes in the same manner that data can be exchanged through a land-based digital network. ACARS makes use of an aircraft's unique identifier, and it has several characteristics that are comparable to those used in electronic mail today.

ACARS History

The ACARS system was first specified in the ARINC 597 standard, however it has since been updated to ARINC 724B. ACARS' capacity to deliver real-time data about aircraft performance on the ground is one of its most important features. This has allowed for the identification and planning of aircraft maintenance activities. ACARS signals are automatically routed to the appropriate aircraft operator via a succession of ground-based ARINC (Aeronautical Radio Inc.) computers. The method helps to eliminate the requirement for repetitive HF and VHF voice transmissions while also providing a system that can be logged and tracked. 

ACRAS Components

A Management Unit, which handles the reception and transmission of messages via the VHF radio transceiver, and a Control Unit, which includes a display screen and printer, make up the Aircraft ACARS components. The ARINC ACARS distant transmitting/receiving stations, as well as a network of computers and switching devices, make up the ACARS Ground Network. The ground-based airline operations and associated tasks, such as operations control, maintenance, and crew scheduling, are all part of the ACARS Command, Control, and Management Subsystem.

ACRAS Frequency Range

ACARS signals are divided into two categories: downlink messages sent from aircraft and uplink messages sent from ground stations. The data rate is minimal, and the messages are made up of simple alphanumeric characters. The range extending from 129 MHz to 137 MHz (VHF) is used for the transmission and receiving of ACARS messages. 


Typical ACARS communications transport routine data includes:

  • Passenger Loads 
  • Departure Reports
  • Arrival Reports 
  • Fuel Data
  • Engine Performance Data

The Ground Station can request this information and have it retrieved from the aircraft at regular intervals or on demand. This type of information would have been transmitted by VHF voice communication prior to ACARS. ACARS employs both ground-based and aircraft-based hardware and software. 

ACARS Messages

ACARS Printed Message
ACARS Message

It's worth noting that different countries employ different channels. The following elements make up a typical ACARS message: 

  • Mode Identifier
  • Aircraft Identifier
  • Message Name
  • Block Identifier Message Number 
  • Flight Number 
  • Message Content.


ACARS makes it possible for aircraft and flight crew to remain connected and updated during all phases of flights. It is very useful for operation and maintenance people. The messages save time in case of any maintenance action or operation requirements.  The ground personnel can plan their activities in advance before the landing of the aircraft and clear the aircraft for the next flight. 

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