The pilots had told engineers there had been a disagreement of altitude and airspeed readings based on cockpit alerts, a preliminary report released by Indonesian investigators shows. There was, however, no mention of an AOA disagreement in their write-up, according to the report, and the plane was dispatched on its final flight the next morning from Jakarta.
Not detailed in the manuals, not mentioned in the maintenance history.
Expecting the IAS DISAGREE.
A system which they were not aware of 'in a non normal' environment keeps trimming against their effort to bring the nose up the moment they stop counteracting it.
Very easy post event to identify the trim issue. In that cockpit with a cacophony of aural alerts, warnings, stick shakers that now seem all spurious, identifying the problem quite another.