Manuel CPDLC V3.0. - Service d'Information Aéronautique Enna

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3.4.2 Management of CPDLC connections
Connections should be maintained and terminated to support this requirement; however aircraft may
be connected with another ATSU on occasions such as:
a) When an aircraft is transiting a CPDLC serviceable FIR subject to coordination between ATSUs;
b) During the CPDLC connection transfer process;
c) Where the active connection is retained by the transferring ATSU subject to prior coordination;
d) When the aircraft is within a non-serviceable or non-CPDLC FIR and logs on to the ATSU
responsible for the next FIR; or
e) In emergency circumstances.
Care must be taken not to issue clearances or instructions to a flight via CPDLC when it is
under the control of another sector/ATSU.
3.4.3 CPDLC connection sequence
A CPDLC connection attempt can only occur after the AFN logon has been completed. The CPDLC
connection is initiated by sending the CONNECTION REQUEST message by the Algiers ACC and
is established when the CONNECTION CONFIRM message is received from the aircraft:
a) If there is no existing connection, the avionics will accept this connection as the active connection.
b) If there is an existing connection, the avionics will check that the initiating ATSU has been
established as the next data authority. If so, the avionics will accept this connection as the non-active
connection.
c) In all other situations, the avionics will reject the connection request.
CONNECTION REQUEST
(CR1)
CONNECTION CONFIRM
(CC1)
CPDLC Connection Sequence
ATSU
Operation Manual of CPDLC V3.0 Algiers FIR 13