AIRPLANE
OPERATIONS
MANUAL
NAVIGATION AND
COMMUNICATION
OCTOBER 02, 2001
2-18-24
Page
1
Code
02
HONEYWELL MARK III COMMUNICATIONS
MANAGEMENT UNIT (CMU)
The airplane may optionally be equipped with Honeywell’s Mark III
Communications Management Unit (CMU). Additional information on
functions and operations can be obtained in the manufacturer’s
manual.
The Mark III Communications Management Unit (CMU) is an airborne
communications router that supports data link service access between
the following aircraft data link applications and their corresponding
ground service providers:
− Aeronautical Operational Communication (AOC)/Airborne Flight
Information System (AFIS).
− Controller Pilot Data Link Communication (CPDLC).
− Automatic Dependent Surveillance (ADS).
The CMU is based on ARINC Characteristic 758 and can be upgraded,
by software download, to an Aeronautical Telecommunications
Network (ATN) router when protocols and application infrastructure are
available to support Communications, Navigation and Surveillance/Air
Traffic Management (CNS/ATM) data link applications. The CMU
provides an Aeronautical Radio, Inc. (ARINC) 724B compatible data
link router through which all character-oriented data are transmitted to
and from the ground Aircraft Communications Addressing and
Reporting System (ACARS) network.
There are several levels of user interfacing. The CMU´s operational
crew interface is provided through a Control Display Unit (CDU),
printer, and data loaders.
Access to the ground network is provided via several ACARS air-
ground sub-networks listed below:
− Satellite Communications (SATCOM).
− Very High Frequency (VHF).
− High Frequency (HF).
− Mode-S (future).
− Ultrahigh Frequency (UHF) (future).
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