Hi A33Zab,
Originally Posted by A33Zab
The only escape, I can think of, is that NAV ADR DISAGREE (ATA34) warning is transmitted by FCDC (ATA27) as detected by FCPC, thus being external and therefore requires CMC to search for correlated failures.
But I have to study the books again, if mentioned somewhere.
Basically, you don't need to look at that for ECAM messages: external/internal detection is also related to fault message classification and correlation, while ECAM messages would be sent in realtime, as displayed on the Engine Warning Display (E/WD). In any ACARS sequence, they would be ahead of the subsequent related system faults (if any).
The main problem in addressing the timming of an ACARS sequence is that maintenance in-flight report (CFR) is different from post flight reports (PFR) so as to identify the correlation between the related faults and cockpit effect messages (ECAM or flag/advisory):
Unlike the CFR, the PFR presents correlations between the fault and cockpit effect messages. The relative positions of the messages in a CFR and in the corresponding PFR may therefore be different.
Now, it seems clear to me if I look at BEA explanations in the first interim report (p. 25-27)
All the messages are timed to the nearest minute. The timing of an ECAM message consists of the time of its acquisition by the CMC, and that of a fault message is the time at which the correlation window opened. It is therefore possible in a CFR to find an ECAM message preceding a fault message that is nevertheless timed one minute before it.
In order to transmit the messages by ACARS, the CMC sends them to the ATSU.
* ECAM messages are transmitted in real time as soon as they are acquired.
* Flag or advisory messages are transmitted as soon as they have been confirmed.(1)
* Fault messages are transmitted as soon as the corresponding correlation window is closed.
________________
(1) The CMC acquires certain ECAM messages from the FWC, in the order that the latter transmits them. This is not necessarily the order in which those messages were displayed on the Engine Warning Display (E/WD). Up to one hundred messages can be acquired in one second. The messages indicating a flag or an advisory are received from the DMCs and must be confirmed for between 2.4 and 3 seconds in order to be acquired. They are timed once this confirmation has been made.