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EUROCONTROL > ATM Performance > EATM > ACARS > Overview 

Overview

Scope

The current scope of ACARS covers three datalink services:

Digital-Automatic Terminal Information Service (D-ATIS)
D-ATIS messages contain operational information required by aircraft before take-off and landing such as runway in use, current weather, airport and facility conditions. The pilot can downlink a message request (RAI) specifying the airport and whether the ATIS is required for Arrival (A), Departure (D), Arrival with automatic update (C) or En route (E). In return, the pilot receives an uplinked ATIS Report (DAI). A Flight Service Message (FSM) can be sent if the usual uplink ATIS Report is inappropriate or the D-ATIS Service is not available at the requested airport.

Departure Clearance (DCL) – also known as Pre Departure Clearance (PDC)
Using DCL, the pilot sends a Request for Departure Clearance Downlink (RCD) and receives a Departure Clearance Uplink (CLD) from ATC which contains the cleared destination, cleared runway, type of departure and route, squawk code, departure time, next frequency, current ATIS identifier. The pilot can then send back an acknowledgement: Departure
Clearance Readback Downlink (CDA). Procedures can vary from one State to another.

Oceanic Clearance (OCL)
On receipt of the pilot-initiated Oceanic Clearance Request Downlink (RCL), ATC sends an Oceanic Clearance Uplink (CLX) which specifies the cleared destination, entry point and route, flight level and Mach number to maintain for passage through the oceanic region. On receipt of the oceanic clearance the pilot can send an acknowledgement: Oceanic Clearance Readback Downlink (CLA).

AAG (ATS ACARS Group) Objectives

The objective of the AAG is to harmonise existing data link services (DCL, D-ATIS and OCL), provided by individually developed ATS ground systems, over ACARS and AOA (ACARS over AVLC) in terms of interoperability, performance and safety aspects.

AAG Tasks

The overall tasks of the AAG are to:
  • Collect information about existing data link implementation
  • Identify problems

  • Report to the Users
  • Report to the relevant body (EUROCAE WG45, AEEC - Airlines Electronic Engineering Committee, etc.) in order to ensure a solution to the problems
On-going detailed tasks are to:
  • Track the standard base (EUROCAE and RTCA) to specify Service Level Agreements (SLA) between ATS and communication service providers and defining associated compliance tools for the communication and ATS ground systems (including procedures).
  • Provide compliance tools to be used to substantiate compliance with ED85 and ED89 specifications.
  • Co-ordinate with other appropriate EATM areas as necessary and identify any requirement for co-ordination with organisations outside EUROCONTROL (e.g. AEEC, EUROCAE, EU, FAA, IATA, ICAO).
  • Monitor on-going work within AEEC and EUROCAE and any other bodies as appropriate for the achievement of the standards.
 
  Last validation: 10/01/2006