Perhaps I am missing something here as this technical discussion is quite esoteric but Boeing advise ...."failure condition that can occur
during manual flight only." The bolding from Boeing.
So all this discussion around pilots being under skilled and not being able to sort out an issue after disconnected the AP becomes even more interesting as the FCOM bulletin suggests that if the AP was flying the issue would have been resolved? Perhaps there is more significant information to come, perhaps once the FDR information has been released. At this stage it is about
PR departments getting in with their version to bias the discussion to suit corporate aims.
And
How can "Automatic disengagement of autopilot" be an effect from AOA disagree, if the failure condition "can occur during manual flight only"?
I'm a little bothered here. I truly believe most here are smart and understand systems analysis at least enough to comprehend what the Boeing AD is telling us here, but the statements above have me frowning. Is this really so confusing?
Boeing states that a failure of an AOA sensor can cause the AP to kick off or not be select-able in the first place if the AOA was already iffy. So let's assume that happened here. The crew took off things seemed fine, but once in the air they either engaged the AP which then dropped out, or were unable to engage the AP due to AOA disagreement. So no automatics. The AD is referring to stabilizer trim under control of the flight control computer, which with an iffy AOA input will cause nose down trim to be applied in increments lasting up to 10 seconds, while in manual flight.
They HAVE TO BE in manual because the very condition the AD refers to
disables the autopilot.
So, no more "if only they turned on the AP", right?
- GY