ATIMS - AIR TRAFFIC SERVICES (ATS) - DESCRIPTION AND OPERATION

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1. General

A. Air Traffic Services-General
The Air Traffic Services are in charge of the ATC FANS A applications:
. ATS Facilities Notification (AFN) for connection with an ATC ground center,
. Controller-Pilot Data Link Communications (CPDLC),
. Automatic Dependent Surveillance (ADS) for aircraft path surveillance.
The Air Traffic Services (ATS) use the Air Traffic Control (ATC) Future Air Navigation System (FANS) B for datalink communications in continental area and during cruise phase.
The Air Traffic Services are in charge of the ATC FANS B applications:
. Context management FANS B application,
. Controller-Pilot Data Link Communications (CPDLC) application.
The Air Traffic Services are in charge of:

the ATC FANS A applications:
. ATS Facilities Notification (AFN) for connection with an ATC ground center,
. Controller-Pilot Data Link Communications (CPDLC),
. Automatic Dependent Surveillance (ADS) for aircraft path surveillance.
and of the ATC ARINC 623 applications:
. Departure Clearance (DC) application
. Oceanic Clearance (OC) application
. Automatic Terminal Information Service (ATIS) application.

(1) AFN application
The AFN application enables an ATS facility to become aware of the aircraft capabilities and provides an exchange of address information. The Facilities Notification messages have no function related to the direct control of the aircraft by an ATC center.

(2) CPDLC application
The CPDLC application enables the dialog between the flight crew and the Air Traffic Controller through the management of uplink and downlink text messages.
A pre-defined set of messages is used, but free text can also be sent by the pilot or the controller.
For uplink messages, the CPDLC application has these functions:

display of a message on the DCDU located on the center instrument panels, as soon as the message is received on-board,
management of the message file if several messages have been received, the message priority is taken into account,
flight crew alert of an uplink message arrival, via the Flight Warning System,
display of a message on the MCDU when the messages are too long to be entirely displayed on the DCDU (for example: the flight plan). In such a case, only a part of the message is presented on the DCDU, but the message can be read on the MCDU,
transmission to the ground of the flight crew answer from the DCDU,
loading of messages in aircraft avionics system (for example: the flight plan in the Flight Management System).

For downlink messages, the CPDLC application has these functions:

management of the MCDU for crew message preparation,
display of downlink messages on the DCDU for crew review before ground transmission.

(3) ADS application
The purpose of the ADS application is to generate ADS messages for transmission to the ground as directed:

The ADS application enables the aircraft to provide, via datalink, data derived from on-board navigation and position-fixing systems. This includes aircraft identification, four-dimensional position and additional data as appropriate.
An ADS agreement is an ADS reporting plan which establishes the conditions of ADS reporting (data required by the ground system and frequency of ADS reports). The terms of the agreement are exchanged between the ground system and the aircraft by means of a contract or a set of contracts.
An ADS contract is an agreement between the ADS ground-user and the ADS air-user where the conditions of reports are specified. There are three types of contracts: Periodic, Event and Demand contracts. They specify under what conditions ADS reports are initiated and what data are contained in.

(4) Context management FANS B application
The context management FANS B application establishes the datalink communications between the aircraft and the ATC center. It uses the Data Link Initiation Capability (DLIC) service which provides the ATC center with the necessary information to establish the datalink communications.

(5) CPDLC application
The CPDLC application enables the dialog between the flight crew and the Air Traffic Controller through the management of uplink and downlink text messages.

(6) AFN application
The AFN application enables an ATS facility to become aware of the aircraft capabilities and provides an exchange of address information. The Facilities Notification messages have no function related to the direct control of the aircraft by an ATC center.

(7) CPDLC application
The CPDLC application enables the dialog between the flight crew and the Air Traffic Controller through the management of uplink and downlink text messages.
A pre-defined set of messages is used, but free text can also be sent by the pilot or the controller.
For uplink messages, the CPDLC application has these functions:

display of a message on the DCDU located on the center instrument panels, as soon as the message is received on-board,
management of the message file if several messages have been received, the message priority is taken into account,
flight crew alert of an uplink message arrival, via the Flight Warning System,
display of a message on the MCDU when the messages are too long to be entirely displayed on the DCDU (for example: the flight plan). In such a case, only a part of the message is presented on the DCDU, but the message can be read on the MCDU,
transmission to the ground of the flight crew answer from the DCDU,
loading of messages in aircraft avionics system (for example: the flight plan in the Flight Management System).

For downlink messages, the CPDLC application has these functions:

management of the MCDU for crew message preparation,
display of downlink messages on the DCDU for crew review before ground transmission.

(8) ADS application
The purpose of the ADS application is to generate ADS messages for transmission to the ground as directed:

The ADS application enables the aircraft to provide, via datalink, data derived from on-board navigation and position-fixing systems. This includes aircraft identification, four-dimensional position and additional data as appropriate.
An ADS agreement is an ADS reporting plan which establishes the conditions of ADS reporting (data required by the ground system and frequency of ADS reports). The terms of the agreement are exchanged between the ground system and the aircraft by means of a contract or a set of contracts.
An ADS contract is an agreement between the ADS ground-user and the ADS air-user where the conditions of reports are specified. There are three types of contracts: Periodic, Event and Demand contracts. They specify under what conditions ADS reports are initiated and what data are contained in.

(9) Departure Clearance (DC)
DC service provides automated assistance to request and deliver departure information and clearances. The objective is to reduce flight crew and controller workload and to diminish clearance delivery delays.
The flight crew initiate the DC service at sending of a DC request which allows to receive a DC clearance from the ground ATC center. Moreover, DC clearance can be received directly without any previous DC request.
DC requests are composed on the MCDU DC request pages.
DC request messages are displayed on the DCDU for flight crew validation or cancellation (before the message is sent to the ground).
The DC application on the MCDU and DCDU displays are available during all flight phases.

(10) Oceanic Clearance (OC)
The OC provides automated assistance to request and deliver an oceanic clearance from the Oceanic ATC Center prior to enter oceanic airspace.
The OC provides the following capabilities:

Oceanic Clearance request
Oceanic Clearance reception
Oceanic Clearance readback
Oceanic Clearance confirmation.

The OC application on the MCDU and DCDU displays are available during all flight phases. However, OC uplink messages received during takeoff or landing are inhibited and displayed 2 minutes after the beginning of the phase that comes after. It is possible to initiate the OC service, either :

the flight crew send an OC request which activates on ground the delivering of OC clearance or
the ground ATS center sends an OC clearance directly to the airborne without request.

(11) Automatic Terminal Information Service (ATIS)
The ATIS application allows the flight crew to request and obtain information on active terminal conditions, such as runway, approach procedure, meteorological parameters (wind, visibility, weather, clouds, runway surface conditions...) etc.
The ATIS supplements the existing availability of ATIS as a voice broadcast service provided at aerodromes worldwide.
ATIS provides the following capabilities:

Request for ATIS information
Reception of ATIS report.

The ATIS application is available only on the MCDU displays and during all the flight phases.

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2. System Description

A. General
The ATC applications use these components:

the Air Traffic Service Unit (ATSU)
the two Datalink Control and Display Units (DCDU) located on the left and right center instrument panels
the two illuminated ATC MSG pushbutton switches
and the Multipurpose Control and Display Units (MCDU).

(1) ATSU
The main functions of the ATSU are:

to host various datalink applications, including both Airline Operational Control (AOC) and ATS
to provide management and access to the various datalink services available in the aircraft
to provide management and access to the various datalink networks available in the aircraft.

(2) DCDUs
The DCDUs are the Human-Machine Interface (HMI) means dedicated to the ATC applications.
The DCDUs are managed by the ATSU. The ATSU prepares and organizes data in screen pages and processes crew orders received by means of function keys called soft keys.
They let the flight crew:

display data received from the ATC center
send/answer messages to/from the ATC center.

(3) ATC MSG pushbutton switches
The ATC MSG pushbutton switches provide the flight crew with a visual alert (the lights of these pushbutton switches flash) when an ATC message arrives. This alert is cancelled when you push the two ATC MSG pushbutton switches or when the flight crew answer the corresponding message.
An aural alert is associated with the visual alert. The aural alert is generated by the Flight Warning System (FWS) through the Audio Management Unit (AMU). This alert is cancelled when you push the two ATC MSG pushbutton switches.

(4) MCDUs
The MCDUs give access to ATC pages to enter parameters, justify responses and generate messages.
The ATSU is the interface between the MCDUs and the DCDUs for message processing and assembly.

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3. Interface

A. Interface for AFN Application

(1) Flight Management and Guidance Computer (FMGC) data
The AFN application receives the following data from the FMGCs:

flight number

(2) Centralized Fault Display Interface Unit (CFDIU) data

Aircraft Registration Number

(3) Display Management Computer (DMC) data
The DMCs provide the same information as the FMGC data in case of FMGC failure.

(4) Transponder (XPDR) mode S
ICAO 24 bits address

(5) Flight Management System (FMS)
Aircraft position

B. Context Management Application
The context management application receives the following data:

Flight number from the Flight Management and Guidance Computers (FMGC) or from the Display Management Computers (DMC) if there is an FMGC failure
Aircraft Registration Number from the Centralized Fault Display Interface Unit (CFDIU)
ICAO 24-bit address from the ATC/Mode S transponder
Aircraft position from the FMGCs.

C. Interface for ADS Application

(1) FMGC data
The FMGCs receive the ADS state: Automatic report in ON or OFF position.
The ADS application uses a set of parameters from the FMGCs to generate ADS reports to the ground:

Aircraft Position
Speed
Flight Identification
Ground Speed
Wind Speed
Altitude
ADS frames:
. basic group
. predicted route frame
. intermediate projected intent frame
. fixed projected intent frame

NOTE: FMGC data are provided by the guidance master FMGC.

(2) DMC data
The DMCs provide the same information as FMGC data in case of FMGC failure.

(3) FWC data
The FWCs provide the ADS application with "TCAS Healthy" information.

D. Interface for CPDLC Application

(1) DCDUs
The DCDUs are the interface means dedicated to the ATC applications. They provide the flight crew with display capabilities and control means. They also allow the display of messages received from ATC ground center and the sending of answer and messages to the ground center. The ATSU manages the DCDUs and processes and organizes the data in screen pages to be displayed and translates received key codes into crew orders (soft keys).

(2) ATC MSG illuminated Pushbutton Switches
These pushbutton switches provide the flight crew with a visual alert in case of ATC message reception. To press these pushbutton switches cancels the alert.
In addition, the FWCs trigger an oral alert, single or repetitive chime sounds according to the priority of the message.

(3) FMGCs
Both FMGCs operate simultaneously.
One of them is called "communication master" and is in charge of all the exchange with the CPDLC in the ATSU.
The CPDLC exchanges are composed of the following functions:

CPDLC activation
Automatic Report activation
Monitoring of the conditions of the deferred clearances (Position, Altitude and Time)
Monitoring of the conditions of the deferred reports
Immediate Report
Route Clearance (the ATSU sends the clearance to the FMGC, which answers with the result of the loading operation)
Route Clearance Request
Automatic Report Request.

(4) MCDUs
They are used for ATC applications needs in addition to the DCDUs and perform the following functions:

preparation and modification of all the messages initiated by the crew
justifications to negative replies or to a particular request
editing of text
configuration of applications (ADS activation, AFN initialization)
configuration of systems (ATSU management, automatic or on-request printing).

(5) FWS
The FWCs generate aural and visual ATC MSG alerts when a CPDLC message is received.
The ATSU handles this alert operationally (flight phase inhibition, sound and light repetition, synchronization and delay, alert cancel, etc.) while the FWCs handle electrical signal generation (flashing light), aural alert and alarm priority.
The FWC has also in charge the display of the ATSU ECAM messages (Router, ATC and Airline Operational Control (AOC) application).

(6) Printer
Some MCDU pages related to the CPDLC application can be printed (this concerns pages where PRINT function is available on line 6R). It is also possible to print a message displayed on the DCDU ("PRINT" hardkey).

(7) DCDUs
The DCDUs are the interface means dedicated to the ATC applications. They provide the flight crew with display capabilities and control means. They also allow the display of messages received from the ATC center and the sending of answer and messages to the ATC center. The ATSU manages the DCDUs and processes and organizes the data in screen pages.

(8) Illuminated ATC MSG pushbutton switches
These pushbutton switches provide the flight crew with a visual alert when an ATC message arrives. To cancel the alert, it is necessary to push the pushbutton switches.
In addition, the Flight Warning Computers (FWC) trigger an aural alert (single or repetitive chime sounds according to the priority of the message).

(9) MCDUs
They are used for the following functions:

preparation and modification of all the messages initiated by the crew
configuration of the context-management application
configuration of systems (ATSU management, automatic or on-request printing).

(10) FWS
The FWS generates aural and visual alerts when a CPDLC message is received.
Through the FWS, the ATSU manages the aural and visual alerts (flight phase inhibition, sound and light repetition, synchronization and delay, alert cancel, etc.).
The FWS also displays the ATSU ECAM messages (ATC and AOC applications).

(11) Printer
Some MCDU pages can be printed (when the PRINT function is available on line 6R). It is also possible to print a message displayed on the DCDU (PRINT key).

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4. Operation

A. AFN Application

(1) General
The AFN application is a prerequisite to the establishment of air/ground datalink communication between the aircraft based ATS applications and ground ATC centers.
The purpose of the AFN application is to establish contacts with ATC centers without direct active connections. The purpose is to exchange a global application context in order to enable connections for datalink communications between the aircraft and ATC centers.
This context consists of:

General aircraft identifiers: Flight Number, coded on up to 10 characters and Aircraft Registration Number, coded on 7 characters and 24 bits ICAO address which allow a correct message routing/addressing.
ATC context: list of ATC applications available aboard the aircraft, associated with their software version numbers.

The connection management is separated into two main procedures:

The Initial Notification procedure
. either manually initiated by the flight crew at ATSU start-up, following a connection failure or after an ATS system shutdown.
. or automatically triggered upon reception of a Contact Advisory message, when the aircraft arrives from an area where its datalink capabilities were not used.
The Contact Advisory procedure.

(2) Initialization
As soon as the ATSU router is initialized, the AFN application is active and ready to be used. The AFN application is de-activated when the ATSU power supply is cut-off.
No contact with a ground ATC center can be successfully achieved if these data are not available to the aircraft:

Flight Number
Aircraft Registration Number
Aircraft position
Communication means status.

For that purpose, the AFN application cyclically acquires and monitors the Flight Number provided by the FMGCs:

If the Flight Number is not available, it must be entered through the NOTIFICATION page on the MCDU (ATC page dedicated to the AFN application).
Whenever the Flight Number changes, the AFN takes the new value into account.

After every initialization, the AFN application indicates to the CPDLC application that no connection with an ATC center is available yet. The AFN application waits for an initial notification procedure initiated by the crew.

(3) Initial Notification procedure

ATIMS - Initial Notification Procedure ** ON A/C NOT FOR ALL

This procedure enables the aircraft AFN to introduce itself to a given ATC center and to make it aware of its application context:

To do this, the crew sends the 'NOTIFY*' command from the NOTIFICATION page, on the MCDU. So, a contact downlink request is generated by the aircraft AFN to the ground ATC center. This message contains the application context, the aircraft position and the ATC center ICAO code.
Then, the AFN application waits for the ATC center reply. The reply from the ground is an uplink message which contains similar information (Flight Number, Aircraft Registration Number and ATC context). This list gives the applications available on the ATC center associated with reason codes. Each application reason code indicates to the aircraft AFN whether the ground ATC center can support its application versions.
If the notification procedure is successful, the AFN application transmits the ICAO code of the contacted ATC center to the CPDLC application which can open an active connection.

NOTE: The code of the ATC center is memorized in a non-volatile memory. Thanks to this memorization, whenever the ATSU resets, the ICAO code of the last active ATC center is automatically displayed on the NOTIFICATION page.

(4) Contact Advisory procedure

ATIMS - Contact Advisory Procedure ** ON A/C NOT FOR ALL

At any time, an ATC center can ask the aircraft AFN to contact another ATC center, due to become the active center in the next FIR region.
This procedure called Contact Advisory is used to transmit to the AFN application an uplink message. This message contains the current ATC center address and the next ATC center address:

Once the ATC uplink message is received,
the AFN application sends a downlink message to the current ATC center to indicate that the Contact Advisory request was accepted.
Then, the aircraft AFN automatically initiates a notification procedure with the next ATC center.
Once the notification acknowledgement is received,
the AFN sends another downlink message to the first ATC center that contains the next ATC center address. It also indicates whether the notification procedure was successfully achieved or not.

NOTE: At the same time, the AFN compares the ICAO code contained in the notification acknowledgement with the code expected by the CPDLC application (given in the Contact Advisory uplink message).

(5) Power cut-off
After power cut-off, the AFN application receives the power cut-off type from the System Management services of the A/C Interface Software:

if the power cut-off is less than 300 ms, this type of interrupt is totally transparent for the flight crew and the ATC center.
if the power cut-off is more than 300 ms or after an ATSU reset, the saved data are re-initialized and the AFN application performs a new complete initialization. The connections with the ATC ground center are lost and the flight crew have to initiate a new Initial Notification procedure.

B. Context Management Application

(1) General
The context management application establishes datalink communications between the aircraft and the ATC centers.
This application consists of:

General aircraft identifiers: Flight Number coded on up to 10 characters, Aircraft Registration Number coded on 7 characters and 24-bit ICAO address to route/address the messages.
ATC context: list of the ATC applications available on the aircraft.

Connection with the ATC center can be performed:

manually through the initial notification initiated by the flight crew at ATSU start-up, following a connection failure or after a system shutdown, or
automatically upon reception of a Contact Advisory message, when the aircraft arrives from an area where its datalink capabilities could not be used.

(2) Initialization
As soon as the ATSU router is initialized, the context management application is active and ready for use.
Contact with an ATC center is successfully achieved only if these data are available:

Flight Number
Aircraft Registration Number
Aircraft position
Communication means (VHF3 or SATCOM).

The Flight Number is transmitted to the context management application by the FMGCs. When the Flight Number changes, the context management application receives the new Flight Number.
After every initialization, the context management application indicates to the CPDLC application that no connection with an ATC center is available. The flight crew have to initiate an initial notification procedure.
The context management application is de-activated when the ATSU is de-energized.

(3) Initial notification procedure

ATIMS - Initial Notification Procedure ** ON A/C NOT FOR ALL

This procedure is used to establish communications with an ATC center and to provide the application context:

To do this, the flight crew select the 'NOTIFY*' command on the NOTIFICATION page, on the MCDU. A contact downlink request is generated to the ATC center. This message contains the application context, the aircraft position and the ATC center ICAO-code.
The reply from the ground is an uplink message which contains similar information (Flight Number, Aircraft Registration Number and ATC context). This message gives the context of the applications available on the ATC center and indicates whether the ATC center can support the aircraft application versions.

NOTE: The code of the ATC center is memorized in a non-volatile memory. After an ATSU reset, the ICAO code of the last active ATC center is automatically displayed on the NOTIFICATION page.

(4) Contact Advisory procedure

ATIMS - Contact Advisory Procedure ** ON A/C NOT FOR ALL

At any time, an ATC center can ask the aircraft context-management application to contact another ATC center, which will be the active center in the next Flight Information Region. This procedure is called Contact Advisory.
The uplink message contains the address of the active ATC center and the address of the next ATC center:

Once the ATC uplink message is received, the flight crew send a downlink message to the active ATC center to indicate that the request was accepted.
Then, the context management application automatically initiates a notification procedure with the next ATC center.
Once the notification acknowledgement is received,
the context management application sends another downlink message to the first ATC center that contains the address of the next ATC center. It also indicates whether the notification procedure was successfully achieved or not.

(5) Power cut-off
If the power cut-off is less than 300 ms, it is imperceptible to the flight crew and the ATC center.
If the power cut-off is more than 300 ms or after an ATSU reset, the saved data are re-initialized and the context management application performs a new complete initialization. The connections with the ATC center are lost and the flight crew have to initiate a new Initial Notification procedure.

C. CPDLC Application

(1) General
The CPDLC application enables the dialog between the flight crew and the Air Traffic Controller through management of datalink messages (uplink and downlink messages).
A pre-defined set of messages is used, but free text can also be sent by the pilot or the controller. The pre-defined messages are split into different categories depending on their operational use. Each category has its own processing.

(2) CPDLC connection management
Only one ATC center is connected with the aircraft at a given time.
It is called the active ATC center.
The CPDLC connection is only established upon ATC center request.
This connection request is accepted only after a successful AFN notification procedure with this ATC center.
The name of the active ATC center is displayed on the DCDU, on each CPDLC message, and also on the default screen.
The status of the CPDLC connection is displayed on the CONNECTION STATUS page, on the MCDU.
The connection with an ATC center can be interrupted either upon ATC request or upon flight crew request, through the CONNECTION STATUS page.
The connection is considered as terminated if no exchange was performed for at least 16 minutes.

(3) CPDLC message
Each message is composed of a set of basic elements which correspond to the existing phraseology used by current ATC procedures:

More than 180 basic elements are used to compose the different uplink messages.
More than 80 basic elements are used to compose the downlink messages.

These messages are related to:

altitude clearances,
speed, offset, flight route modification,
departure clearances,
information, negotiation, urgency messages,
instruction of frequency modification,
automatic report, crew confirmation,
crew request for clearances, etc.

(4) General message management

(a) Uplink ATC message reception
The arrival of a message which comes from the controller is associated with a dedicated ATC alert, which is both visual and aural.

1 The aural alert is a phone ring.
According to the message priority, the sound is more or less repetitive:

The basic ATC alert for usual clearances is first emitted 15 seconds after the corresponding message arrival. It is then emitted every 15 seconds.
The urgent ATC alert for urgent clearances is first emitted 5 seconds after the corresponding message arrival. It is then emitted every 5 seconds.

2 ATC visual alert
The visual ATC alert consists in two ATC MSG pushbutton switches flashing on each side of the glareshield:

this alert is cancelled when you press the two ATC MSG pushbutton switches or when you process the corresponding message,
this alert is also used to remind the flight crew that a deferred clearance condition monitoring or a report condition monitoring has expired.

(b) Downlink message process
The downlink message process consists in the following steps:

the MCDU gives access to specific ATC pages in the ATC MENU page
the flight crew enter the required parameters on the concerned ATC page,
the ATSU processes the message corresponding to this set of elements,
the message is then displayed on the DCDU
the flight crew give the order to send the message to the ATC ground center as they press the associated soft key on the DCDU.

(c) Display of messages on DCDU
The DCDUs are the basic control and display interface for CPDLC operations.
Both DCDUs display the same information at the same time.
Messages are displayed on the DCDUs with their associated parameters and commands:

Any uplink CPDLC message which comes from the controller is displayed on the DCDUs and the flight crew use the function keys on the DCDU for basic answer commands.
Any downlink CPDLC message addressed to the controller is also displayed on the DCDUs before sending ordered by the flight crew.

1 Message filing on the DCDUs
Messages are filed in a chronological order.
The flight crew can answer or send a message in any order.
New messages from the controller are displayed immediately if they are in DISTRESS or EMERGENCY type.

2 Message sending
The flight crew command the sending of a message when they press the SEND soft key on one DCDU.

3 Message storing
A message is removed from the DCDU display when it was processed and closed. The flight crew can recall it on the MCDU, on the MSG LOG or MSG RECORD page or if they press the RECALL command on the DCDU.

4 Message printing
Any received message can be printed if you press the PRINT hard key on the DCDU.

(d) MCDU control and display
Two MCDUs out of three can be used simultaneously by the flight crew for ATC use.
On the MCDU, the specific ATC pages can be accessed:

if you press the ATC COMM mode key, or
if you press the line key adjacent to the ATSU prompt on the MCDU MENU page.

The MCDUs are used as control and display for the CPDLC application:

data entry for message edition,
access to previously exchanged messages (MSG LOG or MSG RECORD function).

1 ATC pages
The different ATC pages enable the crew to:

Enter alphanumeric data for downlink message edition:
The data entered is first displayed in the MCDU scratchpad. Then, the pilot presses the line key adjacent to the datafield where he wants to put the data.

NOTE: The ATSU checks the data format. If the format is not recognized or if the data value is out of range, an error message is displayed in the MCDU scratchpad.

Enter data in dedicated fields in order to generate message elements for the edition of request messages, justifications or responses.

NOTE: A FREE TEXT page also enables to enter any text.

Enter data for the edition of emergency messages.
Enter data for the sending of report message to the ATC center.
Display previously processed ATC message, including the associated given responses. This is called the LOGBOOK or MSG RECORD function.

2 Message storing on the MCDUs
The flight crew store the messages when they are completely processed.
When a message has been previously stored, the flight crew can review it later on the MSG LOG or MSG RECORD page on the MCDUs.
Last stored message can be immediately displayed again on the DCDU if the flight crew press the RECALL soft key.

(5) General
The CPDLC application enables communications between the flight crew and the air traffic controller through datalink text messages (uplink and downlink messages).
A pre-defined set of messages is used, but free text can also be sent by the controller. The pre-defined messages are split into different categories depending on their operational use. Each category has its own processing.

(6) CPDLC connection management
Only one ATC center is connected with the aircraft at a given time.
It is called the active ATC center.
The CPDLC connection is only established upon ATC center request.
The name of the active ATC center is displayed on the DCDU, on each CPDLC message, and also on the default screen.
The status of the CPDLC connection is displayed on the CONNECTION STATUS page, on the MCDU.
The connection with an ATC center can be interrupted either upon ATC request or upon flight crew request, through the CONNECTION STATUS page.

(7) CPDLC message
Each message is composed of a set of basic elements which correspond to the existing phraseology used by current ATC procedures:

More than 180 basic elements are used to compose the different uplink messages.
More than 80 basic elements are used to compose the downlink messages.

These messages are related to:

altitude clearances
speed, flight route modification
information, negotiation
instruction of frequency modification
crew confirmation
crew request for clearances, etc.

(8) General message management

(a) Uplink message reception
The arrival of a message from the ATC center is associated with ATC visual and aural alerts.

1 Aural alert
The aural alert is a phone ring.
According to the message priority, the sound is more or less repetitive:

The basic ATC alert for usual clearances is first emitted 5 seconds after the message arrival. It is then emitted every 5 seconds.

2 Visual alert
The lights of the two ATC MSG pushbutton switches flash on each side of the glareshield when an uplink message arrives.

this alert is also used to remind the flight crew that a deferred clearance condition-monitoring or a report condition monitoring has expired.
this alert is cancelled when you push the two ATC MSG pushbutton switches or when the flight crew answer the corresponding message.

(b) Downlink message processing and assembly
The downlink message processing consists in the following steps:

the MCDU gives access to specific ATC pages in the ATC MENU page
the flight crew enter the required parameters on the concerned ATC page
the ATSU processes the message corresponding to this set of elements
the message is then displayed on the DCDU
the flight crew send the message to the ATC center.

(c) Display of messages on the DCDUs
Both DCDUs display the same messages at the same time with their parameters and soft key indications:

Any uplink CPDLC message which comes from the ATC center is displayed on the DCDUs and the flight crew use the soft keys on the DCDU to answer.
Any downlink CPDLC message addressed to the ATC center is also displayed on the DCDUs before the flight crew send it.

1 Message filing on the DCDUs
Messages are filed in a chronological order.
The flight crew can answer or send a message in any order.

2 Message sending
The flight crew command the sending of a message when they push the soft key adjacent to the SEND indication on the DCDU.

3 Message storing
A message is removed from the DCDU display once it is processed and closed. The flight crew can recall it on the MCDU, on the MSG LOG or MSG RECORD page or if they push the soft key adjacent to the RECALL indication on the DCDU.

4 Message printing
Any received message can be printed if the flight crew push the PRINT key on the DCDU.

(d) Control and display on the MCDUs
Two MCDUs out of three can be used simultaneously by the flight crew for ATC use.
On the MCDU, the specific ATC pages are displayed:

when the flight crew push the ATC COMM mode key, if available or
when the flight crew push the line key adjacent to the ATSU indication on the MCDU MENU page.

The MCDUs are used to:

enter data for message edition
get access to messages previously exchanged (MSG LOG or MSG RECORD function).

1 ATC pages
The ATC pages are used to:

Enter alphanumeric data for downlink message edition.

NOTE: The ATSU checks the data format. If the format is not recognized or if the data value is out of range, an error message is displayed in the MCDU scratchpad.

Enter data in dedicated fields to generate message elements for the edition of request messages or responses.
Display ATC messages previously processed, including the associated given responses. This is called the LOGBOOK or MSG RECORD function.

D. ADS Application

(1) General
The ADS application is a datalink application which automatically provides the ground ATC center with reports. They contain data derived from on-board navigation and position-fixing systems, including aircraft identification, four-dimensional position and additional data.
The ADS operates either in Normal mode or in Emergency mode.
The ADS is a ground-initiated application.

(2) Initialization
After ATSU initialization, the ADS application is armed in Normal mode (ADS "ARMED" by default) and ready to receive a connection request from the ground.
The ADS application remains activated as long as the flight crew do not order a de-activation or no connection is initiated by the ground.
Except for activation/deactivation and emergency mode request/cancel, the flight crew have no action on the ADS application. Processings are automatic for the crew.
If the flight crew deactivate the ADS application, ADS "OFF" is displayed.
If an ADS connection is established by the ground, ADS "CONNECTED" is displayed.

(3) Connection management
The ADS application can manage five connections simultaneously.

(a) Connection activation
The ADS receives and analyses the connection request from the ground:

If the request is accepted, the ADS initializes a new context associated with this connection and sends an acknowledgement message to the ground.
If the request is not accepted, the ADS does not process the received data and sends a negative acknowledgement Message to the ground.
if some parameters are not consistent, a non-compliance message is sent to indicate to the ground which parameters are incorrect.

(b) Connection termination
When a connection is terminated, all current contracts on this connection are cancelled and the ADS sends a disconnection signal to the ground.
A connection is terminated in the following cases:

ground request
three consecutive connection denial
end of the flight
time-out expired without any active contract (16 minutes)
flight crew request for inactive ADS application
flight crew request to disconnect an ATC
loss of communication >16 minutes

For a connection termination, all current contracts on this connection are cancelled. The context associated to this connection is cancelled, and the ADS sends a disconnection signal to the ground.
It is also possible to disconnect independently each connected center via a dedicated page (ADS DETAIL) accessible on the CONNECTION STATUS page.
ADS downlink reports messages are bufferized 30 minutes and then purged.
Except for activation/deactivation and emergency mode request/cancel, the flight crew have no action on the ADS application. Processings are automatic for the crew.
If the flight crew deactivate the ADS application, ADS "OFF" is displayed.
If an ADS connection is established by the ground, ADS "CONNECTED" is displayed.

(4) ADS message types
When the connection is activated, the ADS waits for data request from the ground.
The condition of reporting as data required, frequency of ADS reports are determined in an ADS reporting plan: the "Agreement".
The terms of the "Agreement" are exchanged between the ATC center and the aircraft by means of a contract:

Periodic Contract
Certain reports have to be sent at a specified frequency.
Event Contract
Certain reports are required at the occurrence of a specific event or sequence of events.
Demand Contract.
One-time polling of the avionics is required for specific reports.
Cancel All Contracts and Terminate Connection
Cancel Contract
Cancel Emergency Mode.

(a) Uplink ADS messages
An uplink message is composed of one or more tag depending on the type of contract required on the request:

TAG VALUE TAG DESCRIPTION

1 Cancel All Contracts and Terminate Connection

2 Cancel Contract

6 Cancel Emergency Mode

7 Periodic Contract

8 Event Contract

9 Emergency Periodic Contract

10 Lateral Deviation Change

11 Reporting Rate

12 Flight Identification Group

13 Predicted Route Group

14 Earth Reference Group

15 Air Reference Group

16 Meteorological Group

17 Airframe Identification Group

18 Vertical Rate Change

19 Altitude Rate Change

20 Waypoint Change

21 Aircraft Intent Group

(b) Downlink ADS messages
The downlink message contains the "Tag Value" which indicates the type of contract :

TAG VALUE TAG DESCRIPTION

3 Acknowledgement

4 Negative Acknowledgement

5 Non compliance Notification

6 Cancel Emergency Mode

7 Periodic Contract

9 Emergency Periodic Contract

10 Lateral Deviation Change

12 Flight Identification Group

(Flight Number)

13 Predicted Route Group

(Latitude, longitude, altitude,

estimated time to go to next waypoint)

14 Earth Reference Group

(True track, ground speed,

vertical rate data)

15 Air Reference Group

(True track, Mach speed,

vertical rate data)

16 Meteorological Group

(Wind speed, true wind direction,

temperature data)

17 Airframe Identification Group

(ICAO aircraft identification)

18 Vertical Rate Change

19 Altitude Rate Change

20 Waypoint Change

22 Intermediate Projected Intent Group

(Distance, true track, altitude,

projected time data)

23 Fixed Projected Intent Group

(Latitude, longitude, altitude,

projected time data)

REASON CODE DESCRIPTION

1 Duplicate on-request group tag

2 Duplicate reporting rate tag

3 Event contract request with no data

4 Improper operational mode tag

5 Incorrect ADS contract request number

6 Already existing ADS contract

request number

7 Undefined contract request tag

8 Undefined error

9 Not enough data in request

10 Floor altitude parameter greater than

or equal to ceiling altitude parameter

11 Vertical rate change threshold

equal to zero

12 Aircraft intent projection time

parameter equal to zero

13 Lateral deviation change threshold

equal to zero

(d) Periodic Contract Content
The Periodic Contract contains the following requests:

ADS Request (Tag Value No 7)

ADS Contract Request Number

Reporting Rate (Tag Value No 11)

Flight ID Group (Tag Value No 12)

Predicted Route Group (Tag Value No 13)

Earth Reference Group (Tag Value No 14)

Meteorological Group Data (Tag Value No 16)

Airframe ID Group (Tag Value No 17)

Air Reference Group (Tag Value No 15)

Aircraft Intent Group (Tag Value No 21)

Aircraft Intent Projection Time

NOTE: For periodic contract, the ADS application uses timers.

(e) Event Contract content
For event contract, the ADS application monitors the concerned data provided periodically by the Integration Services of the ATSU.
The Event Contract contains the following requests:

ADS Request (Tag Value No 8)

ADS Contract Request Number

Vertical Rate (Tag Value No 18)

Vertical Rate Threshold

Altitude Range (Tag Value No 19)

Ceiling

Floor

Waypoint Change (Tag Value No 20)

Lateral Deviation (Tag Value No 10)

Lateral Deviation Threshold

(f) Demand Contract content
For on-demand contract, the report is sent immediately, except for an "intent group data" request because the FMGCs provide these data after 60 seconds.
The basic ADS group, which contains the aircraft latitude, longitude, altitude, time stamp and Figure Of Merit (FOM), is mandatory in each message sent.
Additional information is available and structured into "On-Request Groups".
Each previously established connection can support one periodic contract, one event contract and one demand contract.

(g) ADS Cancel Contract content
The ADS Cancel Contract request is composed as follows:

ADS Request Tag Value No 2

ADS Contract Request Number

(h) Cancel All Contracts and Terminate Connection content
The Cancel All Contracts and Terminate Connection request is composed as follows:

ADS Request Tag Value No 1

ADS Contract Request Number

(i) Cancel Emergency Mode content
The Cancel Emergency Mode request is composed as follows:

ADS Request (Tag Value No 6)

ADS Contract Request Number

(5) Message generation and sending
Once the connection is activated, the ADS waits for ground request.
When the ground request is received by the ADS, it is analyzed for acceptation or denial.
Each established connection can support one periodic contract, one event contract and one demand contract.
The reports sent to the ground cannot be modified or displayed by the crew. The crew cannot select the parameters. Only the ground generates the contract: data content and transmission frequency.
Data for ADS report generation are acquired periodically by the ATSU from the FMGCs, the FWCs and the DMCs except for the "intent group" data. In this case, the ADS application sends a specific request to the FMGCs in order to acquire the "intent group" data.
These data are transmitted to the ATSU in frame and are time-stamped with UTC time. In case of FMGC failure, position data are provided by the DMCs without any time stamp.
The ADS application monitors the conditions of reporting data: frequency, on-demand, events. As soon as the required condition is met, the ADS application:

generates the report from the available data, and
sends the report to the ground through the air/ground communication functions which are in charge of coding and formatting the messages according to the corresponding protocols.

For periodic contract, the ADS application uses timers.
For event contract, the ADS application monitors the concerned data provided periodically by the ATSU Integration services.
For on-demand contract, the report is sent immediately, except in a case of an "intent group data" request. In this case, the ADS application waits 60 seconds for data availability.

(6) ADS activation/de-activation

(a) ADS mode
ADS has three different modes:

OFF which means that ADS is OFF, and refuses all the connections and the contract request
ARMED which means that ADS is ready to receive connections and contract request, but there is no contract which exists.
CONNECTED which means that ADS is connected and has at least one active contract with an ADS ground center.

(b) Normal mode
It is possible to activate/deactivate the ADS function through the "CONNECTION STATUS" page.
The ADS function is "ARMED" in the normal mode by default at the system initialization.
When the ADS status is switched to "OFF", it stops all the current processings and starts a disconnection processing on all the established connections. When th ADS is "OFF", all new connection requests are refused.
When the ADS status is "ARMED", it is ready to accept a new connection.
As soon as one or more connections are established between ground ATC and aircraft, the ADS status changes from "ARMED" to "CONNECTED". The access prompt (ADS detail) is displayed to allow flight crew to show the different ATCs which have ADS contract with the aircraft (this does not include the type of contract). Moreover, the connection status of the ADS with the number of connected ATCs is displayed on the DCDU.
It is possible to access "ADS DETAIL" page to the flight crew to see the different connected ATCs.

NOTE: It is possible that some center code are just displayed with 7 character address because no previous notification was performed. So no correlation between the 4 character ICAO code and the 7 character address is possible.

(c) Emergency mode
When a CPDLC message which contains the "MAYDAY" message element ("EMERGENCY" MCDU page) is sent, this activates the "ADS EMERGENCY" mode.
In this mode, the ADS application sends emergency report to the ground ATC which has already a contract with the aircraft.
Conversely, when the CPDLC message "CANCEL EMERGENCY" is sent, this deactivates the ADS "EMERGENCY" mode.
Otherwise, it is possible to the crew to activate or deactivate the ADS emergency mode on the "EMERGENCY" MCDU page if the toggle "EMER ADS": SET ON or SET OFF is selected. The title line indicates whether the ADS emergency mode is ON or OFF.

(7) Power cut-off
The ADS application receives the power cut-off type from the System Management Services:

if the power cut-off is lower than 300 ms, it is transparent for the flight crew.
if the power cut-off is more than 300 ms, the ADS application performs a new complete reinitialization because the contracts with the active ATC center are lost.

E. ARINC 623 ATC applications

(1) Departure Clearance (DC)
DC service provides automated assistance to request and deliver departure information and clearances. The objective is to reduce the flight crew and controller workload and to diminish clearance delivery delays.
The flight crew initiate the DC service at sending of a DC request which allows to receive a DC clearance from the ground ATC center. Moreover, DC clearance can be received directly without any previous DC request.
DC requests are composed on the MCDU DC request pages.
DC request messages are displayed on the DCDU for flight crew validation or cancellation (before a message is sent to the ground).
The DC application on the MCDU and DCDU displays are available during all flight phases.

(a) Sequence

1 Departure Clearance (DC) request
The DEPARTURE CLEARANCE request is prepared on the MCDU, displayed on the DCDU and sent to the ground.

2 Departure Clearance (DC) reception
An uplink clearance is received, the aural and visual warnings are activated, and the message is displayed on the DCDU.

3 Departure Clearance (DC) readback
If the pilot accepts the clearance, he selects the proposed ACK answer on the DCDU and sends it to the ground together with the clearance.

4 Departure Clearance (DC) confirmation
The ground confirms that the acknowledgement for this clearance was received, this is displayed on the DCDU.

NOTE: If the crew prefer to REFUSE the received clearance, then no downlink message is sent to the ground and this must be done by voice contact (this is indicated on the DCDU when REFUSE is selected).

(b) Downlink DC request

Departure Clearance Request ** ON A/C NOT FOR ALL

Departure requests are composed on the MCDU through the A623 DEPARTURE request pages.
When the flight crew access to the MCDU A623 DEPARTURE request pages, the application fills in automatically the following datafields with available and valid data extracted from the ATSU:

ATC flight number
departure airport
destination airport
ATIS version
aircraft type.

The DC application considers valid an ATC Flight Number received with 1 to 10 characters; the application accepts and displays the alphanumeric characters string of 1 to 7 characters. The application does not allow the flight crew entries on the flight number field.

NOTE: The A623 flight number is not modifiable because the used value is directly extracted from the FMS system, which is the unique entry. The flight crew must ensure consistency between the FMS flight number and the ATC flight number needed to dialogue with the ATC center (as given to the ground in the ATC flight plan).

The flight crew can enter and modify the Departure and Arrival fields and the gate field (the gate number is not mandatory on the MCDU displays).
The ATIS version field is filled in automatically with the last version of departure ATIS report received by datalink. This report is displayed on the ATIS report page or automatically printed by the flight crew, when available.
The flight crew can enter and/or modify the ATIS version field.
The flight crew can enter and modify the aircraft type field.
The DC application allows the flight crew to request display of departure requests from the MCDU to the DCDU when all mandatory datafields of request are filled.
If the gate number field is empty on the MCDU at composition of the DC request, the DC request message is displayed on the DCDU with the displayed default value "-----".
The DC application uses the ICAO address of departure airport datafield as supplementary address for routing purpose of air-ground messages.
When a Departure request message is sent to the ground, the DC application waits for the ground DSP acknowledgement uplink message during the Network Acknowledgement Timer.
If a positive acknowledgement is received from the ground DSP when a departure request is sent:

the DC application displays the "SENT" information to the flight crew on the DCDU which is then storable.

If a negative acknowledgement is received from the ground DSP or if the ack DSP timer has expired when a departure request is sent:

the DC application indicates the "SEND FAILED" information on the message displayed which is then storable.

Uplink Departure Clearance ** ON A/C NOT FOR ALL

On reception of an uplink DC clearance, the DC application checks that the message is valid:

If the uplink DC clearance is valid, it is displayed with white title and cyan fields.
If it is partially valid, it is displayed exactly as received from the ground, as a chain of characters completely white.
If it is invalid, it is disregarded without any notification to the crew nor the ground center.

NOTE: No departure clearance request is displayed after take-off.
If the flight crew refuse the DC clearance, the application displays the clearance in "REFUSE" state with a message on the DCDU that indicates that the crew must revert to voice. This message can be stored.

(2) Oceanic Clearance (OC)
The Oceanic Clearance (OC) provides automated assistance to request and deliver an oceanic clearance from the Oceanic ATC Center prior to enter oceanic airspace.
The OC application on the MCDU and the DCDU displays are available during all flight phases.
It is possible to initiate the OC service either:

when the flight crew send an OC request which activates on ground the delivering of OC clearance
when the ground ATS center sends an OC clearance directly to the airborne without request.

(a) Sequence

1 Oceanic Clearance request
The OCEANIC CLEARANCE request is prepared on the MCDU, displayed on the DCDU and sent to the ground.

2 Oceanic Clearance reception
An uplink clearance is received, the aural and visual warnings are activated, and the message is displayed on the DCDU.

3 Oceanic Clearance readback
If the pilot accepts the clearance, he selects the proposed ACK answer on the DCDU and sends it to the ground together with the clearance.

4 Oceanic Clearance confirmation
The ground confirms that the acknowledgement for this clearance was received, this is displayed on the DCDU.

(b) Downlink OC request

Downlink OC request ** ON A/C NOT FOR ALL

Oceanic requests are composed on the MCDU A623 OCEANIC request pages.
When the flight crew access to these pages, the application fills in automatically the ATC flight number with available and valid data extracted from the system.
The OC application considers valid an ATC Flight Number received with 1 to 10 characters. The application displays the alphanumeric characters string of 1 to 7 characters. The application does not enable the flight crew to enter the flight number.
The OC application allows the flight crew to request display of oceanic requests from the MCDU to the DCDU when all the mandatory datafields of request are filled.
The OC application provides the flight crew with a mean to enter the ICAO address of the Oceanic ATC center on the MCDU A623 OCEANIC request pages. This is mandatory for routing purpose to send the request to the Oceanic ATC center.
The OC application uses the oceanic ATS center datafield entry on the MCDU as the supplementary address for routing purpose of air-ground messages.
While an oceanic request message is sent to the ground, the OC application waits for the ground DSP acknowledgement uplink message during the Network Acknowledgement Timer (2 minutes).
If a positive acknowledgement is received from the ground DSP when an oceanic request is sent:

the OC application displays the "SENT" information to the flight crew on the DCDU which can be stored.

If a negative acknowledgement is received from the ground DSP or if the ack DSP timer has expired when an oceanic request was sent:

the OC application indicates the "SENT FAILED" information on the message displayed which can be stored.

Uplink OC clearance ** ON A/C NOT FOR ALL

On reception of an uplink OC clearance, the application checks that the message is valid.

If the uplink clearance is valid, it is displayed with white title and cyan fields.
If it is partially valid, it is displayed exactly as received from the ground, as a chain of characters completely white.
If it is invalid, it is disregarded without any notification to the crew nor the ground center.

NOTE: The flight crew may have sent an oceanic request just after take-off in order to anticipate entry in the oceanic area.

If the flight crew refuse the OC clearance, the application displays the clearance in "REFUSE" state and a message is displayed. This message requires the crew to revert the voice. This message can be stored.
If the flight crew accept the OC clearance, the application displays the clearance in the "ACK" state.

(3) Automatic Terminal Information Service (ATIS)
The ATIS application allows the flight crew to request and obtain information on active terminal conditions, such as runway, approach procedure, meteorological parameters (wind, visibility, weather, clouds, runway surface conditions...) etc.
The ATIS supplements the existing availability of ATIS as a voice broadcast service provided at aerodromes worldwide.
ATIS provides the following capabilities:

Request for ATIS information
Reception of ATIS report.

The ATIS application is available only on the MCDU displays and during all the flight phases.

(a) Sequence

1 ATIS report request
The ATIS report request is prepared on the MCDU, and sent directly from the MCDU.

2 ATIS report reception
An ATIS report is received: as it is accessible from the MCDU only, no aural or visual warnings are activated. The full report can be displayed on the MCDU.

3 Updated ATIS report reception
If the pilot has required the update service, a new ATIS report is sent each time it is updated.

(b) Downlink ATIS request
ATIS requests are composed on the MCDU ATIS request pages.
The ATIS application is initiated when the flight crew send an ATIS request, and the ground ATS system delivers an ATS report to the aircraft.
The application can accept and simultaneously process four distinct requests on four different request lines.
When the flight crew access on the MCDU ATIS request pages, the application fills in automatically three distinct requests. This concerns departure, arrival and alternate airports name and type indicator associated extracted from the system.
If these data are not available, data line allows the crew to enter an airport and an ATIS type.
The Departure type indicator (DEP) is automatically associated to the departure airport request.
The Arrival type indicator (ARR) is automatically associated to the destination and the alternate airport requests.
The application allows setting on or off automatic printing for all the ATIS reports.
The application allows setting on or off automatic update request on each ATIS arrival request line.
The application does not allow the flight crew to make simultaneously identical requests (with the same airport and type indicator).
The application does not allow the flight crew to make simultaneously arrival and update contract requests on the same airport.
The application allows the flight crew to overwrite pre-filled fields (airports and associated type indicator).
If the flight crew have overwritten automatically filled in parameters, the flight crew entry is conserved when the pilot changes pages.
The ATIS application allows the flight crew to send ATIS requests directly to the ground from the MCDU ATIS request pages. This is possible when all the mandatory parameters are filled in for a request line.
The Airport address contained in the airport identifier field of the ATIS request is used as the supplementary address for message encoding purpose to the ground.
When an ATIS message is sent to the ground, the application:

displays the "sending" status on the request line
activates the Network Acknowledgement Timer (2 minutes) to wait for the "positive ACK" or "negative ACK" ground acknowledgement message.

If a positive acknowledgement is received from the ground, the "SENT" status is indicated to the flight crew on the request line.
If a negative acknowledgement is received from the ground, the "SEND AGAIN" status is indicated to the flight crew on the request line.
At the timeout of the Network Acknowledgement Timer, the "SEND AGAIN" status is indicated to the flight crew on the request line.
The system allows the pilot to modify a waiting single request by an auto update request on the same airport.
If no ATIS report was received at the end of the ATIS Report Timer on a request, the system displays the "SEND AGAIN" status information.
The application does not allow the flight crew to compose and send a new ATIS update request when an identical update request already exists and waits.
If an automatic update request waits at landing, the application automatically sends an update cancel request to the ground.
If the flight crew request an auto update request on a waiting ATIS request:

the waiting request is discarded (no display of the sending or sent status information anymore)
the update request is available for the flight crew sending.

In this case, the ATIS report is accepted and displayed if it is received.
It is not possible to store or display downlink ATIS requests in the MSG Record pages.

(c) Uplink ATIS report
When an uplink ATIS report is received, the application checks that the message is valid.
If it is valid:

the application displays an indication of reception with the time and the version of the report received on the waiting request line with an access prompt on the MCDU ATIS report page.

If it is invalid:

the application discards the message.

If it is partially valid:

it is exactly displayed as received from the ground, as a chain of characters, except the airport which is mandatory to correlate the ATIS report and the request (and so the line).

ATIS reports are entirely displayed on the MCDU ATIS reports pages.
When the flight crew select the access prompt of the ATIS report on the request line, the application displays the MCDU ATIS report pages. These pages display the whole content of the last received report, called current report.
The application rejects any valid ATIS report not linked to a waiting request in terms of airport request and type indicator.
The application allows access to previous ATIS report (if any) from the MCDU ATIS current report pages.
Only the two last ATIS reports are saved and accessible by the flight crew.
If automatic printing is set-on, the application automatically prints any ATIS report received.
When the ATIS application waits for a request, with a departure/arrival type indicator, the application accepts and displays the following ATIS report:

An ATIS report with a departure/arrival type indicator
A combined (arrival and departure information are associated) ATIS report with either a departure or an arrival type indicator.

When an automatic update request is pending, the application accepts and displays the following ATIS reports:

consecutive ATIS single or combined reports with arrival type indicator and automatically sent by the ground
a unique ATIS report with arrival type indicator (i.e. the ground does not support update contract); in this case, after sending of request, the application receives an uplink message which indicates that update contract is not supported by the ground. The update contract request becomes non waiting.
The ATIS application automatically forwards to the A623 DC application the ATIS version of the last ATIS departure airport report received. This last ATIS departure airport report was displayed on the ATIS MCDU report pages or automatically printed by the system.
ATIS reports are not stored nor displayed in the MSG Record pages.

F. Management of the DCDU Uplink Messages

(1) Clearance messages

(a) Standard Clearance messages

Example of DCDU Clearance Message ** ON A/C NOT FOR ALL

The standard clearance message is an ATC instruction immediately applicable by the flight crew.

(b) Loadable Clearance messages

Example of DCDU Loadable Clearance Message ** ON A/C NOT FOR ALL

The loadable clearance message is an ATC instruction message which can be loaded in the FMGC, in the secondary flight plan, for evaluation.

Example of DCDU Deferred Clearance Message ** ON A/C NOT FOR ALL

The deferred clearance message is a conditional ATC instruction.
The FMGC monitors the condition. The system recalls the instruction to the flight crew at a time deferred compared to the message reception.
The associated condition of a deferred clearance message may be a time, a lateral or a vertical condition.

(d) Typical sequence of operation

Process of an Uplink Clearance Message ** ON A/C NOT FOR ALL

Process of an Uplink Deferred Clearance ** ON A/C NOT FOR ALL

The possible answers to a clearance are:

WILCO for acknowledgement
STANDBY to delay the message process
UNABLE for a negative response (with possible justification).

(2) Information messages

(a) Information messages with mandatory response

Example of DCDU Information Message With Mandatory Response ** ON A/C NOT FOR ALL

The information message enables the flight crew to anticipate a future clearance or to know an information relative to the flight operational conditions.
The flight crew acknowledge this message through a " ROGER " reply which can be preceded by a "STANDBY" response.

(b) Information messages with no need of response

Example of DCDU Information Message With No Need of Response ** ON A/C NOT FOR ALL

The messages without response are ATC information messages.
The flight crew are not supposed to send any reply to this kind of messages.

Processing of an Uplink Information Message ** ON A/C NOT FOR ALL

The possible answers to an information message are:

ROGER for acknowledgement
STANDBY for process delay.

(3) Confirmation messages
The confirmation message is an ATC request to confirm a given information.

(a) Flight data confirmation

Example of Flight Data Confirmation ** ON A/C NOT FOR ALL

For some messages, current FM data is proposed to the flight crew as reply to the ground.
For example, the response to "CONFIRM [speed]" is "PRESENT SPEED [speed]".
This data can be modified by the flight crew through the MCDU before it is sent.

(b) General data confirmation
Sometimes, the confirmation message is relative to general data as:
The response to "CONFIRM [atis]" is entered through the MCDU: "ATIS [code]".

Process of an Uplink Confirmation Message ** ON A/C NOT FOR ALL

(4) Report message

(a) Report request message

Procedure of Report Request Message ** ON A/C NOT FOR ALL

The report message is an ATC request to send a report when a given operational condition is fullfilled.
The FMS monitors the condition.
The system presents the report message to the flight crew when the condition is reached.
The associated monitored condition can be an altitude, a lateral or a vertical condition.

(b) Typical sequence of operation

Process of an Uplink Report Request Message ** ON A/C NOT FOR ALL

The possible answers to a report request are:

ROGER for acknowledgement
STANDBY for process delay.

(5) Question message and "NO ANSWER" message

Processing of an Uplink Question Message and a "NO ANSWER" Message ** ON A/C NOT FOR ALL

Procedure of Question Message ** ON A/C NOT FOR ALL

The possible answers to a question message are:

Affirmative
Negative (possible justification)
Standby for process delay.

(6) Negotiation messages

(a) Standard negotiation message

Example of Standard Negotiation Message ** ON A/C NOT FOR ALL

The negotiation message is an ATC request concerning the aircraft ability to reach a given altitude with a given constraint, a time or a position.
The flight crew either accept with an "AFFIRMATIVE" reply or reject it with a "NEGATIVE" reply.

(b) Open Negotiation messages
The open negotiation message is an ATC request concerning the aircraft ability to reach a given altitude, a speed or an offset.
The flight crew reply with the time at which the aircraft will be able to reach the given parameter, a speed, an altitude or an offset.
This reply is a free text which reformulates the question.

Process of an Uplink Negotiation Message ** ON A/C NOT FOR ALL

The possible answers to a negotiation message can be:

positive with "We can accept [altitude] by [time]" (for example)
negative with "We cannot accept [altitude] by [time]" .

(7) Clearance messages

(a) Standard clearance messages

Example of Clearance Message on DCDU ** ON A/C NOT FOR ALL

The standard clearance message is an ATC instruction immediately applicable by the flight crew.

(b) Typical sequence of operation

Processing of an Uplink Clearance Message ** ON A/C NOT FOR ALL

The possible answers to a clearance are:

WILCO for acknowledgement
STANDBY to delay the message processing
UNABLE for a negative response.

(8) Information messages

(a) Information messages with mandatory response

Example of DCDU Information Message With Mandatory Response ** ON A/C NOT FOR ALL

The information message enables the flight crew to anticipate a future clearance or to know an information relative to the flight operational conditions.

(b) Typical sequence of operation

Processing of an Uplink Information Message ** ON A/C NOT FOR ALL

The possible answers to an information message are:

ROGER for acknowledgement
STANDBY to delay the message processing.

Example of DCDU Information Message With No Need of Response ** ON A/C NOT FOR ALL

The flight crew do not have to send any reply.

(9) Confirmation and report messages
The confirmation message is an ATC request to confirm a given information.

(a) Flight data confirmation

Example of Flight Data Confirmation on the DCDU ** ON A/C NOT FOR ALL

The ATC center requires current FM data in some messages.
For example, the response to "CONFIRM ASSIGNED LEVEL" is " ASSIGNED LEVEL (level value)".
This data can be modified by the flight crew through the MCDU before it is sent.

(b) Typical sequence of operation

Processing of an Uplink Confirmation Message ** ON A/C NOT FOR ALL

(10) Question message and "NO ANSWER" message

Processing of an Uplink Question Message and a "NO ANSWER" Message ** ON A/C NOT FOR ALL

DCDU - Question Message ** ON A/C NOT FOR ALL

The possible answers to a question message are:

Affirmative
Negative (possible justification)
Standby to delay the answer.

(11) Negotiation messages

(a) Open negotiation messages
The open negotiation message is an ATC request concerning the aircraft ability to reach a given altitude.
The flight crew reply with the time at which the aircraft will be able to reach the given data altitude.

(b) Typical sequence of operation

Processing of an Uplink Negotiation Message ** ON A/C NOT FOR ALL

The possible answers to a negotiation message can be:

positive with "WE CAN ACCEPT (altitude value) AT (time)" (for example)
negative with "WE CANNOT ACCEPT (altitude value) AT (time)" .

G. Management of the Downlink Messages

(1) Request messages

(a) Standard request message
The request messages enable the flight crew to require a clearance to the ATC center.

(b) Route request message
The Route Clearance request message enables the flight crew to require a route clearance to the ATC ground center.
The route definition will be performed in the secondary flight plan of the FMS.

Process of a Downlink Request Message ** ON A/C NOT FOR ALL

(2) Report messages
The report message is a flight crew information message to the ATC ground center.
It enables the flight crew to transmit operational flight data to the ATC.

(a) Text messages
The text message is a flight crew message for the ATC ground center.
It enables the flight crew to send any kind of message whose content can be either preformatted or free text.
This message can be sent alone or further to:

an Unable reply,
a request message,
a report message,
an emergency message.

(b) Emergency messages
The emergency message is a flight crew emergency message for the ATC ground center.
It enables the flight crew to signal an emergency situation to the ATC ground center.
This message can be sent with additional information about the flight.
The sending of this type of message activates or de-activates the ADS emergency mode.

Process of a Downlink Report Message ** ON A/C NOT FOR ALL

Process of a Downlink Emergency Message ** ON A/C NOT FOR ALL

(3) Request messages

(a) Standard request message
The request messages enable the flight crew to request a clearance from the ATC center.

(b) Typical sequence of operation

Processing of a Downlink Request Message ** ON A/C NOT FOR ALL

H. DCDU Control and Display

DCDU - Control and Indicating ** ON A/C NOT FOR ALL

(1) General
The DCDUs are the basic control and display interface for ATC application
Both DCDUs display the same information at the same time.
Each DCDU displays the formatted information received from the ATSU which is in charge of data processing and DCDU display management. The ATSU sends complete pages to be displayed and acquires pilot commands by means of the configurable soft key selected by the pilot on the DCDU.

(2) DCDU command keys

BRT key enables to increase the brightness of the DCDU or to switch on the DCDU.
DIM key enables to reduce the brightness of the DCDU or to switch off the unit if the key is pressed for at least five seconds.
PRINT key enables to print the message currently displayed on the DCDU.
MSG+ key enables to display the next message registered in the DCDU queue.
MSG- key enables to display the previous message registered in the DCDU queue.
PGE+ key enables to display the next page of the message currently displayed on the DCDU.
PGE- key enables to display the previous page of the message currently displayed on the DCDU.
Four reconfigurable soft keys enable to activate the associated command function. Each function key is associated with a message in a given state. When you press one of these keys, the state of the message (except for OTHER function) and the set of associated function soft keys are modified.

(3) DCDU display
The display characteristics are as follows:

five colors are used for displayed characters: cyan, white, green, amber and magenta.
five lines of twenty four characters for the message content
two character sizes can be displayed per line.
a given line can consist of elements of several colors.
the characters or character string can be underlined or displayed in reverse video.

(a) Time information
The time stamp of ATC initiated message or flight crew initiated message is displayed in the upper left corner of the DCDU screen:

'2224Z' for 22 hours 24 minutes

Z for ZULU/UTC time

(b) ATC name information
The ATC data authority-name associated with the displayed message is shown in the upper center section of the DCDU and only in the first page of the message:

'FROM NTTT CTL' for an uplink message

'TO NTTT CTL' for a downlink message

(c) Status information
The status of the message currently displayed is shown in the upper right corner. The status message characterizes the processing state of the message:

When the answer of a message is selected, the corresponding message status is displayed in cyan reverse video:
AFFIRM, CANNOT, NEGATV, ROGER, STBY, UNABLE, WILCO, ANSWER, CANCEL, OTHER, LOAD, CLOSE, MODIFY, RECALL.
When a message is processed, this same status is displayed in green, reverse video in the status area.
After a loss of the CPDLC connection, the uplink pending message is displayed with the 'ABORT' status.
When an uplink pending message is received, the 'OPEN' status is displayed until answer selection.
When the transmission of a message fails, the 'OPEN' status is displayed in amber.

(d) Information message
The information message is displayed in the center bottom section of the DCDU. It provides the flight crew with general information related to the message currently displayed or to the processing associated with the message.
The DCDU erases its screen and displays 'INVALID DATA' if the ATSU does not send a new page two seconds after a pilot command order.

(e) Message and page number
The 'MSG XX/YY' and 'PGE XX/YY' indications give the rank of the message currently displayed in the DCDU message file and the rank of the page currently displayed.
These indications are displayed in white and the 'MSG XX/YY' indication flashes when a new message is filed.

(f) Particular DCDU displays
Before ATC notification or after disconnection, the DCDU displays the 'NO ACTIVE ATC' message or a blank display.
If the DCDU does not receive any data from the ATSU, the DCDU displays the 'NO DATA' message.
If the received data are not valid, the DCDU displays the 'INVALID DATA' message.
Each DCDU page is split into fields. Each field displays a different type of information.

(4) Message content
The messages exchanged between the flight crew and the air traffic controllers are displayed on the DCDU:

Messages are split into five lines and fifty pages maximum.
When no message is displayed, the DCDUs display a default black screen, which gives the name of the current active ATC center.
An uplink message is processed when the sending of the answer is selected.
A downlink message is processed when the sending is selected.
Text and parameters of a message, which do not require any further action relative to the communication with ATC controller, are displayed in green.
Non pending uplink messages turn green when the flight crew select the sending of the corresponding downlink message, except for messages which can be stored directly by the crew.
These messages are green as soon as they are displayed.
Downlink messages are in green reverse video when the flight crew select their sending.

--------------------------------------------------------------------------

! ! Message not processed ! Message processed !

--------------------------------------------------------------------------

! Uplink message ! Normal video ! Normal video !

! ! Not green ! Green !

--------------------------------------------------------------------------

! Downlink message ! Reverse video ! Reverse video !

! ! Not green ! Green !

--------------------------------------------------------------------------

(5) Message colors
Black color is used for screen background.
Green color is used for monitored parameters.
Magenta color is used for parameters monitored by the FM.
Amber color is used for:

Error message or status message in correspondence with the functions configured
ABORT messages status
Access to the "EMERGENCY" pages

White color is used for:

Content of the uplink messages
Status of a "CLOSED" message
Condition parameters (not monitored) of the uplink messages
Information messages

Cyan color is used for:

Content of the downlink messages
Name of the function key
Parameter of execution in the uplink messages
Status of an "OPEN" message.

(6) Reconfigurable soft keys
Four reconfigurable areas are dedicated to the display of the command label associated with the reconfigurable soft key.
This table gives the commands that are linked to communication:

---------------------------------------------------------------------------

LABEL ! USE ! Associated ! Level !

! ! Softkey ! !

---------------------------------------------------------------------------

AFFIRM ! Definitive positive reply to a message ! Bottom right ! 1 !

---------------------------------------------------------------------------

CANNOT ! Definitive negative reply to a message ! Top left ! 1 !

---------------------------------------------------------------------------

NEGATV ! Definitive negative reply to a message ! Top left ! 1 !

---------------------------------------------------------------------------

ROGER ! Definitive positive reply to a message ! Bottom right ! 1 !

---------------------------------------------------------------------------

SEND ! To confirm/send command of a message ! Bottom right ! 1 !

---------------------------------------------------------------------------

STBY ! Deferred reply to a message ! Top right ! 1 !

---------------------------------------------------------------------------

UNABLE ! Definitive negative reply to a message ! Top left ! 1 !

---------------------------------------------------------------------------

WILCO ! Definitive positive reply to a message ! Bottom right ! 1 !

---------------------------------------------------------------------------

This table gives the commands that are linked to on-board processing:

---------------------------------------------------------------------------

LABEL ! USE ! Associated ! Level !

! ! Softkey ! !

---------------------------------------------------------------------------

ANSWER ! Removal from the DCDU of a multi ! Bottom right ! 1 !

! element message and splitting up of ! ! !

! this message ! ! !

---------------------------------------------------------------------------

CANCEL ! - Removal of a prepared downlink ! Top left ! 1 !

! message from the DCDU ! ! !

! - Cancellation of a selected reply to ! ! !

! an uplink message ! ! !

---------------------------------------------------------------------------

OTHER ! Access to the second level of the ! Bottom left ! 1 & 2 !

! reconfigurable softkeys ! ! !

---------------------------------------------------------------------------

LOAD ! Command to load in the FMGEC ! Top right ! 2 !

---------------------------------------------------------------------------

CLOSE ! - Removal of the message from the DCDU ! Bottom right ! 1 !

! message file and transfer to the ! ! !

! Logbook function ! ! !

! - Removal of a reminder message from ! ! !

! the DCDU message file ! ! !

! - Removal of a recalled message from ! ! !

! the DCDU and switch back to the DCDU ! ! !

! message file ! ! !

---------------------------------------------------------------------------

MODIFY ! - Access to the MESSAGE EDITION page ! Top right ! 1 !

! on the MCDU ! ! !

! - Update of the FM data for a downlink ! ! !

! message ! ! !

---------------------------------------------------------------------------

RECALL ! - Recall of the latest stored/cleared ! Bottom right ! 2 !

-----------------------------------------------------------------

! - Recall of the latest stored/cleared ! Bottom right ! 1 !

! message when the default page is ! ! !

! displayed ! ! !

---------------------------------------------------------------------------

NOTE: The OTHER command is not displayed if there is no selectable command on the second level of the reconfigurable soft keys.

Each command label corresponds to a specific function associated with the processing state of the message (i.e. 'LOAD' command).
Each command is associated with a single reconfigurable soft key.
A function key is displayed with a star each time that function is effectively possible for currently displayed message.
A function key is displayed with a star each time that function is effectively possible for the currently displayed message.
An available function label is displayed framed in cyan with a star when it is selectable by the crew.
A function key possible for a given message but unavailable is displayed in white, without star.
DCDU command labels are not selectable for two seconds when the corresponding message is displayed for the first time on the DCDUs.
The commands WILCO, AFFIRM, ROGER and SEND are displayed but not selectable as long as the flight crew:
. have not displayed the last page of the corresponding message, or
. have printed the whole message.
A double press on a given function key corresponds to a conventional utilization sequence (for example: 'ROGER' + 'SEND').
Level 1 commands are immediately visible for the first display of a message.
Level 2 commands are only displayed and accessible after a press on the 'OTHER' command. This command gives access to another function level where the function keys have changed the command label.

(7) Message display handling
Up to twenty nine messages are filed in the DCDU message file in chronological order. The oldest message is the message number one.
If the message file capacity is reached, the amber message 'FILE FULL' is displayed in the information area of the DCDU.
When an urgent or distress message is received, it is automatically displayed on the DCDU.
When a new message is added in the DCDU file, the number of messages increases and this number flashes. A new message comes from:

the ATC center: new uplink message
the airborne system: reminder message
the MCDU: a flight crew request entered.

If the flight crew send an order to display a downlink message on the DCDU, it is immediately displayed.
When a message is removed from the DCDU file , the next message of the file is displayed.
If there is no next message, the previous message is displayed.
When there is no more message in the file, the default DCDU screen is displayed.

(8) RECALL mode
The RECALL function enables the flight crew to access on the DCDU to the last message that has been stored (after CLOSE command).
A recalled message is presented with the same characteristics as when it was stored except:

the information message 'RECALL MODE'
the 'CLOSE' command on the bottom right soft key
no message numbering.

A recalled message is removed from the DCDU when an Urgent/Emergency message arrives or when the MSG+/MSG- hard key is pressed.
The DCDU display switches back to the message previously displayed.

(9) General
The DCDUs are the basic control and display interface for ATC applications. They have a screen and eleven keys.
Both DCDUs display the same information at the same time.
Each DCDU displays the formatted information sent by the ATSU. The ATSU is in charge of data processing and DCDU display management. It sends complete pages for display and acquires pilot commands by means of four reconfigurable soft keys on the DCDU.

(10) DCDU control
The DCDU has eleven keys:

BRT key to increase the brightness of the DCDU or to switch on the DCDU.
DIM key to reduce the brightness of the DCDU or to switch off the DCDU if the key is pushed for at least five seconds.
PRINT key to print the message currently displayed on the DCDU.
MSG+ key to display the next message registered in the DCDU queue.
MSG- key to display the previous message registered in the DCDU queue.
PGE+ key to display the next page of the message currently displayed on the DCDU.
PGE- key to display the previous page of the message currently displayed on the DCDU.
Four reconfigurable soft keys associated with a set of commands (AFFIRM, CANNOT, ROGER ...). To answer a message, the flight crew push the soft key related to the correct command. Then the status of the message (OPEN, ANSWERED ...) changes.
To get access to other commands, it is necessary to push the soft key adjacent to the OTHER indication.

(11) DCDU display
Before ATC notification or after disconnection, the DCDU displays a blank display.
If the DCDU does not receive any data from the ATSU, the DCDU displays the 'NO DATA' message.
If the received data are not valid, the DCDU displays the 'INVALID DATA' message.
Each DCDU page is split into fields. Each field displays a different type of information:

(a) Time information
The time stamp of the message is displayed in the upper left corner of the DCDU screen:

'2224Z' for 22 hours 24 minutes

Z for ZULU/UTC time

(b) ATC name information
The airport identification code associated with the displayed message is shown on the upper center section of the DCDU and only on the first page of the message:

'FROM NTTT CTL' for an uplink message

'TO NTTT CTL' for a downlink message

When the answer to a message is selected, the status is displayed in cyan reverse video:
NEGATV, ROGER, STBY, UNABLE, WILCO.
When a message is processed, the status is displayed in green reverse video in the status area.
After a loss of the CPDLC connection, the uplink pending message is displayed with the 'ABORT' status.
When an uplink pending message is received, the 'OPEN' status indication is displayed until an answer is selected with one of the soft keys.
When the transmission of a message fails, the 'OPEN' status indication is displayed in amber.

(d) Information message
The information message is displayed in the center bottom section of the DCDU. It provides the flight crew with general information related to the message currently displayed or to its processing.
The DCDU erases its screen and displays 'INVALID DATA' if the ATSU does not send a new page two seconds after a pilot command order.

(12) Message content
The messages exchanged between the flight crew and the air traffic controllers are displayed on the DCDU as follows:

Messages are split into five lines and fifty pages maximum.
When no message is displayed, the DCDUs display a default black screen, which gives the name of the current active ATC center.
Messages displayed in green do not require any further action.

The colors of the messages change with their status:

--------------------------------------------------------------------------

! ! Message not processed ! Message processed !

--------------------------------------------------------------------------

! Uplink message ! Normal video ! Normal video !

! ! Not green ! Green !

--------------------------------------------------------------------------

! Downlink message ! Reverse video ! Reverse video !

! ! Not green ! Green !

--------------------------------------------------------------------------

(13) Message colors
Black color is used for screen background.
Green color is used for monitored parameters.
Magenta color is used for parameters monitored by the Flight Management (FM).
Amber color is used for:

Error message or status indication
ABORT message
Access to the "EMERGENCY" pages.

White color is used for:

Uplink messages
"CLOSED" status indication
Condition parameters (not monitored) of the uplink messages
Information messages.

Cyan color is used for:

Downlink messages
Indications adjacent to the soft keys
Parameter of execution in the uplink messages
"OPEN" status indication.

(14) Reconfigurable soft keys
The four reconfigurable soft keys are associated with a set of commands which are displayed in dedicated areas.
This table gives the commands that are linked to the communications between the flight crew and the air traffic controller:

---------------------------------------------------------------------------

INDICATION! USE ! Associated ! Level !

! ! Soft Key ! !