Hi _Phoenix_,
Why FD didn't step out, as AP disconnected, by design?
BEA asked the same question on Page 210 Final report.
"4.3.7 Ergonomics
The crew did not de-activate the flight directors and did not call out any changes in FMA mode. It is not sure that they noticed the appearances and disappearances of the flight director crossbars. It is likely that the crew did not know of the mode changes when the flight director became active again, reading and assimilating the displays on the FMA in dynamic and stressful conditions not being instinctive or natural. It seems that requiring an action from the crew to re-engage this automatic system would, on the one hand, lead to a consistency with the autopilot and the autothrust, and on the other hand stimulate a check on the modes and the consistency of the commands presented at the time of the re-engagement.
Consequently, the BEA recommends that:
EASA require a review of the re-display and reconnection logic of the flight directors after their disappearance, in particular to review the conditions in which an action by the crew would be necessary to re-engage them; [Recommendation FRAN-2012-047]
Further, even if it is not sure that the crew followed the orders from the flight director while the stall warning was active, the orders from the crossbars were in contradiction with the inputs to make in this situation and thus may have troubled the crew.
Consequently, the BEA recommends that:
EASA require a review of the functional or display logic of the flight director so that it disappears or presents appropriate orders when the stall warning is triggered. [Recommendation FRAN-2012-048]"