Originally Posted by teckgeek
I quote from the 2nd BEA report:
"The reappearance of the flight directors on the PFD when two air speeds will
be calculated that can lead the crew to rapidly engage the autopilot. However,
these speeds, though of the same order, can be erroneous and weak and thus
lead the autopilot to command movements of the flight control surfaces that
are inappropriate for the real speed of the airplane.
In case of automatic disconnection of the autothrust with activation of the
thrust lock function, the absence of appropriate manual adjustment of thrust
can present a risk of an attitude/thrust mismatch, especially when this
disconnection occurs with a low N1 value."
The same report, speaking of 13 cases of A330 airspeed anomalies:
"In seven cases, the autopilot was reconnected during the event. In two of
them, the re-connection occurred when the two speeds were consistent
with each other but were erroneous".
This is of great interest especially when you realize that no latter that last december, Airbus has published a
RED Operating Engeneering Bulletin on that matter ...