User's Guide

User Guide for the Envoy Data Link
Document Number: UG-15000 Rev. A Page 64 of 173
5 ACARS Operations
The Envoy has standard ACARS messaging, which includes associated ATC messages, in a
menu tree structure that supports all phases of flight.
This section describes the default menu structure, page layouts, and field-level inputs for the
standard ACARS menu tree and message set shown in Figure 2-3. Airlines may specify up to 72
custom 2-page screens for ACARS messages.
Many pages contain autopopulated data; although the aircrew can edit these fields, the bus feed
overwrites any manual input. Some unit values may be hardcoded according to configuration
options or ARINC 618/620/622 specifications.
The ACARS menu can be accessed by pressing the ACARS function key at the top of the Envoy
display or by pressing LSK R2 on the Envoy Main Menu.
Note If an Envoy is not configured with ACARS, pressing the ACARS function key or LSK R2 on
the main menu displays a FUNCTIONALITY NOT AVAILABLE message in the scratchpad.
The Envoy manages message transaction sequences and default settings for ATC, ADS, and AOC
messages, including these reporting intervals:
SINGLE EVENT
Aircraft parameter value(s) from one or more A429 data busses that change
state or exceed a threshold for a specified duration. For example, the state of
a door (open/closed) flap (or brake (on/off) can trigger an OOOI event, or 10
minutes after the OOOI state is IN, the ACARS message log will be cleared.
MULTIPLE EVENTS
Multiple events can be cascaded to produce sophisticated event triggers that
rely on a series of conditions to be true before a message is downlinked to
operations or maintenance.
CONTINUOUS
INTERVAL EVENTS
Time- and event-based thresholds, such as exceeding an altitude threshold,
can be defined as triggers; for example exceeding FL320 for more than 2
minutes can trigger a position report message to be sent at 15-minute intervals
while the aircraft is above the threshold altitude.
These event triggers are inherent in many ATC requests, such as weather and position reports.