SERA.15015 Construction of CPDLC
messages
Regulation (EU) 2023/1772
(a) The text of CPDLC messages shall be
composed in standard message format, in plain language, or in abbreviations
and codes. Plain language shall be avoided when the length of the text can be
reduced by using appropriate abbreviations and codes. Non-essential words and
phrases, such as expressions of politeness, shall not be used.
(b) The air traffic controller and the pilot shall construct CPDLC messages
using standard message elements, free text message elements, or a combination
of both. The use of free text message elements by air traffic controllers or
pilots shall, be avoided.
(c) When the implemented CPDLC message set does not provide for specific
circumstances, the competent authority may determine, in consultation with
operators and other air traffic services providers, that it is acceptable to
use free text message elements. In such cases, the competent authority
concerned shall define the display format, intended use and attributes for
each free text message element.
(d) The composition of a CPDLC message shall not exceed five message
elements, only two of which may contain the route clearance variable.
(e) Construction of multi-element CPDLC messages:
(1) When a multi-element CPDLC message requires a response, the response
shall apply to all message elements.
(2) When a single message element clearance or any part of a multi-element
clearance message cannot be complied with, the pilot shall send an “UNABLE”
response for the whole message.
(3) The controller shall respond with an “UNABLE” message that applies to
all elements of the request when no element(s) of a single or multi-element
clearance request can be approved. The current clearance(s) shall not be
restated.
(4) When a multi-element clearance request can only be partially
accommodated, the controller shall respond with an “UNABLE” message applying
to all the message elements of the request and, if appropriate, include a
reason and/or information on when clearance may be expected.
(5) When all elements of a single or multi-element clearance request can be
accommodated, the controller shall respond with clearances corresponding to
each element of the request. This response shall be a single uplink message.
(6) When a CPDLC message contains more than one message element and the
response attribute for the message is “Y”, when utilised, the single response
message shall contain the corresponding number of replies in the same order.
EASA aviation regulations mandate concise CPDLC message construction using standard formats, abbreviations, and codes. Free text should be minimized. Messages are limited to five elements, with restrictions on route clearance variables. Pilots must reject entire multi-element messages if any part is unachievable. Controllers respond similarly to unapproved requests.
* Summary by Aviation.Bot - Always consult the original document for the most accurate information.
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