Originally Posted by
infrequentflyer789
I recall that there has been at least one case where a/p was re-engaged soon after UAS and did the wrong thing due to speeds being in agreement but still erroneous.
The UAS duration was not sufficient to latch Alternate 2 in that case. While it's true that it was possible to re-engage AP in that scenario, the re-engagement had to be manual. The AP will not re-engage itself automatically in any scenario, and because Alt2 was triggered and latched in the case of AF447 even a manual attempt to re-engage AP would have been denied.
Because of the digital nature of the equipment, the AP switch is not a type where AP status can be determined by switch position - AP status is determined by the presence of the Autopilot button light on the FCU and the PFD status instead.
Originally Posted by
BOAC
- I see repeated reference all over PPrune to this being the 'correct action'. Was this in fact so, i.e.a QRH item before 447?
Would need confirmation on the QRH, but "Flight Director : OFF" was definitely a step in the UAS procedure published by Airbus and disseminated to the airlines prior to AF447.