scope:

This DLASD deals with the "Departure Clearance" ATS datalink service implementation as per the operational requirements as described in reference.

It does not cover those experimental implementations of the "Departure Clearance" ATS datalink service, which are based on free text as well as on different ACARS message formats.

The DCL service is an "Aerodrome Control Service", a direct communication from Aircrew to Controller, as defined in reference.

NOTE: The pre-departure clearance in the US is delivered through the airline dispatch office to the aircrew, more than 30 min. before departure. According to FAA it is an AOC application which has a different operational meaning than the Departure Clearance (DCL) as defined in this document. A comparison between the PDC and DCL services is presented in APPENDIX D.

This document does not capture any communication requirement which would be applicable to the specific interface between Communication and ATS domain (e.g. X.25), even if that interface characteristics of low level may transcend a domain boundary (Refer to section A.1 in APPENDIX A). However it does identify, for information purposes, any document of relevance for the implementation of such communication interface.

This document is applicable to an operational environment where the communication services can be supported by communication links:

• which are provided by a single communication service provider,

• which rely partially on services proposed by other communication service providers.