User's Guide

Table Of Contents
User Guide for the Envoy Data Link
Document Number: UG-15000 Rev. A Page 109 of 173
Appendix B AFN Messages
To establish communication for ATS transactions, the ATS facility needs to discover the identity of
the aircraft and the available ATS application(s) (ACARS, CPDLC, FANS, ATN, ADS). Similarly, an
aircraft needs to acquire the ground address of the ATS facility. The ATS Facilities Notification
(AFN) application provides this functionality via the following messages:
Message Label
Intent
FN_CON
Downlink AFN Contact message.
FN_AK
Uplink AFN Acknowledgement message.
FN_CAD
Uplink AFN Contact Advisory message.
FN_RESP
Downlink AFN Response message.
FN_COMP
Downlink AFN Complete message.
The AFN application consists of two basic procedures:
Initial Notification - The Initial Notification procedure allows an aircraft to introduce itself to the
ground end-system in a chosen ATS facility and to make that end-system aware of its aircraft
registration and the ATS data link applications that it supports. The Initial Notification procedure
may be initiated by aircrew action or by an automatic trigger. When initiated, an AFN Contact
message is sent to the ground end-system. If the Initial Notification procedure is successful, the
ATS facility responds with the full seven character address of the ground AFN end-system. This
procedure is known as the AFN LOG-ON.
Request for Notification - The Request for Notification procedure allows an ATS facility to
request an aircraft to notify another ATS facility. The ATS facility initiates the Request for
Notification by sending an AFN Contact Advisory message to the aircraft.