User's Guide
Table Of Contents
- 1 Introduction
- 1.1 Audience
- 1.2 Overview
- 1.3 Envoy CMU Features
- 1.4 Configuration Options for Envoy
- 2 Operation of Envoy
- 3 CPDLC Operations
- 3.1 Log On
- 3.2 Logoff
- 3.3 Lost Connection
- 3.4 Typical Message Composition
- 3.5 ATC Menu
- 3.5.1 ATC Request Menu – FANS 1/A+ and ATN B1 CPDLC Common
- 3.5.2 ATC REPORT Menu
- 3.5.3 WHEN CAN WE EXPECT
- 3.5.4 POS REPORT Message – FANS 1/A+
- 3.5.5 EMERGENCY (MAYDAY) Message – FANS 1/A+
- 3.5.6 ATC MSG LOG
- 3.5.7 CLEARANCE REQUESTS – FANS 1/A+
- 3.5.8 FREE TEXT 1/2
- 3.5.9 ATC VOICE CONTACT Message – FANS 1/A+
- 3.5.10 Cancel EMERGENCY, Cancel ADS
- 3.5.11 Flight Plan Transactions and Monitoring
- 4 Automatic Dependent Surveillance (ADS)
- 5 ACARS Operations
- 6 MAINTENANCE Menu
- Appendix A Acronyms
- Appendix B AFN Messages
- Appendix C Supported CPDLC Messages
- Appendix D ADS-C Tags
- Appendix E ACARS Message Labels
- Appendix F ATSU Call Signs (ICAO, IATA)
- Appendix G Fault Management
User Guide for the Envoy Data Link
Document Number: UG-15000 Rev. A Page 60 of 173
4 Automatic Dependent Surveillance (ADS)
Automatic Dependent Surveillance (ADS) operation is a configuration option for aircraft and
facilities that use two-way ADS messaging:
• ADSF - The airborne application
• ADSG - The ground-based peer (within the Air Traffic Services (ATS) provider system)
The Envoy supports up to five (5) simultaneous ADS contracts with one or more ADSGs. Each
contract specifies the downlink detail and frequency of reports. Most of this is transparent to the
aircrew. The aircrew has the ability to cancel all contracts and to selectively cancel an ADS
contract with a specific ATSU.
The Envoy interface gives the aircrew the ability to:
• Enable or disable ADS
• Put ADS into (and out of) Emergency Mode
• Inhibit an ADSG from sending ADS requests
When ADS-C is active, aircrew are advised to avoid using non-ATC waypoints (such as Abeam
waypoints or Pilot Defined Waypoints) to preclude sending ADS updates that are not part of the
filed flight plan.
4.1 ADS-C
The Envoy has built in support for ADS event contracts. Upon receiving a FANS CPDLC logon
request, an ATSG has the option to establish an ADS-C contract with an aircraft to receive ADS-C
reports on a regular basis. The report content and modulus, or downlink cycle is based on the
ADS-C uplink generated by the ADSU. Actual data reported may vary based on Envoy
configuration options.
An ATSU may request multiple simultaneous ADS contracts to obtain periodic, event-driven, or on-
demand data from a given aircraft.
Note In FANS, an ATSG can request ATC reports that are based on event triggers, route
constraints, and/or time intervals. For more information, see the FANS reports queue,
described in Section 3.5.2.
Periodic contract
An ATSU sets:
• The time interval for an ADS-C report
• The optional groups to include and the modulus, which the frequency that group is included in a
periodic report (for example, a modulus of five indicates that the optional group would be included
with every fifth periodic report sent).
On Demand Contract
An on demand contract allows an ATSU to request a single ADS-C periodic report. A demand
contract does not cancel or modify any other ADS contracts that may be in effect with the aircraft.