OPERATIONS MANUAL

Communications
ACARS – Basics:
The aircraft communications addressing & reporting system (ACARS)
provides datalinks for receiving and transmitting digital information between
ground stations and the aircraft. Information is transferred via satellite
(not in the simulator) or via VHF, and is packed into short messages which
typically refer to maintenance data, administrative tasks, or flight operations,
including CPDLC (for CPDLC refer to chapter FMS). For VHF operations,
ACARS can use VHF C only: the pilot sets the active VHF C frequency on
the RTPs to 137.0; if this is set and ACARS is operational, the RTP indicator
displays the word DATA and the ACARS management unit will tune VHF C
as required (to frequencies other than 137.0; the 137.0 selection on the RTP
is used as a switch only, to disable RTP tuning). When not in DATA mode,
voice communication is possible, but it will not terminate ACARS operation,
and ACARS may, if it fails, interfere with voice communication on VHF C;
for this reason, voice communication is not permitted on VHF C. ACARS
automatically operates when AC bus 2 or 3 is powered.
The crew can access various ACARS features through one of the three
CDUs on the aisle stand. Only one CDU can give access at a time; in normal
operations, the center CDU is used. The design of the ACARS pages and
features is very much airline specific (the simulator provides one design sample
for all aircraft; it also omits pages that refer to airline specific data such as
address data, for instance).
ACARS also logs the OOOI times. OOOI stands for: out—off—on—in.
That is: out of the gate—takeoff—touchdown on the runway—in the gate.
Depending on the current flight phase, ACARS sends reports to the ground
station automatically as follows (partially simplified in the simulator):
1. When all doors are closed and the aircraft starts taxiing:
• Out report
• Refueling report
2. When the landing gear is decompressed:
• Off report
3. When the FMC changes from the cruise to the descent phase:
• ETA report (estimated time of arrival, calculated by the FMC)
4. When the landing gear is compressed:
• On report
5. When the first door opens:
• In report
The OOOI times are reset when a new flight number or another airport is
entered in the FMC. (In the simulator, the reports appear on Instructor >
Situation > Human > Dispatcher on the ACARS telex screen.)
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