Machinbird, re your post 2748.
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When a FAC is disengaged (FAC pushbutton set off) but still valid, the flight envelope function of the FAC remains active.
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Did they use the switches on the overhead panels?
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That would not work too well if the flight envelope protection part of the FAC system was malfunctioning without failing its self test.
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If the FAC is "disengaged" by pushing the FAC set off button on the overhead panel, why does the FAC remain active in any way at all ?
Off is Off in my book.
This reads like "Off is only half off".
What is the point in having an off button for one part of the FAC's funtionality, but not the other part (the flight envelope functions).
Perhaps there should be two buttons, the second one for "flight envelope functions off".
Since there is none, the only option left is the circuit breaker ?
How many times would a FAC be turned off in normal ops, do you think ?
How many times, in what circumstances, and for what reasons, would turning off a FAC by done in the sim ?
Is it implicit in those sim exercises that the the flight envelope functions remain engaged, always, or not ?
If not, is it implicit in ANY sim exercise that total FAC shutdown, by pulling circuit breaker is required, and what the specific circumstances are, and what the consequent implications then are for continued safe flight ?
Do any of those sim'd circumstances and exercises "gell" in any way with any credible circumstance that may have occured on 8501 ?
In other words, could they have identifed (or thought they had identified) a circumstance that they had trained for, and were just working the list, or is it more likely they were in a whole "new world" situation, not trained for, no list printed, and trying to work it out themselves from square one ?
The whole idea of an off button that is not actually an off button at all bugs me.
Talk about "man - machine interface" - jesus - what are the engineers thinking when they design these things ?
It sounds more like a case of - "I can't let you do that Dave" - as in - a "prime directive" - sort of thing.
Machinbird, I do not understand the rationalle of the logic in play here.
"Please Explain".
(It is lunchtime. Perhaps I should go and have some fish and chips).