Aircraft Communications Addressing and Reporting System (ACARS) Flashcards
ACARS is found under ATA code:
23-20
ACARS is used to:
Send short digital messages automatically
Can be used to send aircraft condition and phase reports to dispatchers
Phase of flight reports are commonly known as:
OOOI (pronounced OOHWEE) which stands for Out of gate, Off ground, On ground, and In gate.
Like satellite communication systems, the ACARS requires a:
subscription to a service provider.
On the aircraft, ACARS is connected to what systems?
VHF communications system and an
HF or a satellite communication system.
What is the VHF frequency for ACARS in the United States?
131.550 MHz
(For ACARS to thrive, tune to 131.55)
What band is used for ACARS on international flights?
HF
The ACARS management unit connects to multiple:
communication systems and sends or receives messages automatically.
All ACARs transmissions in the United States are all on one frequency, transmitted messages must be:
as short as possible.
To achieve a short message:
a special code block using 220 characters is transmitted in digital format.
If there is a longer message:
more than one block will be transmitted.
ACARS operates in two modes:
the Demand Mode and the Polled Mode.
The Demand Mode allows:
the flight crew or airborne equipment to initiate communications.
Demand Mode: 🗣️➡️
Polled Mode: 📞⬅️
The Ground Station sends a reply message. If an error or no reply is received:
the MU continues to transmit the message at the next opportunity.
In the Polled Mode:
the system operates only when interrogated by the ground facility.
Demand Mode:🗣️ ➡️
Polled Mode: 📞 ⬅️
The Ground Facility regularly:
uplinks questions to the aircraft equipment and the MU responds with a transmitted message.
What does the MU do?
organizes and formats flight data prior to transmission.
Flight information is transmitted to the ground facility under what circumstances?
Upon request
Information for ACARS is collected from:
several aircraft systems including the
FMS, the Aircraft Integrated Data System (AIDS), and the Central Maintenance
Computer Systems (CMCS).
The ACARS control is managed through the:
Control Display Unit (Boeing) or the
MCDU (AirBus) located on the flight deck.
Various EICAS maintenance pages and CMC fault reports can be sent to:
ground facilities using ACARS.
To downlink a CMC fault report or EICAS maintenance page, the crew would:
access the desired fault on the CDU, and then send the report to the ground facility.
Some of the newest aircraft will:
automatically downlink maintenance data
A BITE circuit within the MU monitors:
the ACARS UM and other related systems.
For the link test to work, the aircraft must be:
within range of an ACARS ground station. Keep in mind VHF range is very limited on the ground.
