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Old 24th Apr 2019, 16:15
  #4284 (permalink)  
GordonR_Cape
 
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Originally Posted by hawk76
Remember, though, this chart was schematic in nature and speculated on what the graph might look like, to illustrate a point about what MCAS was likely doing to achieve its goal. I could be wrong, but I don't think anyone posted an actual plot for the MAX. Still, it is well-informed speculation and to me illustrates the point. And FCeng84's posts on the topic have been particularly enlightening; anyone looking to catch up should search for these.
Point taken, partly speculation about how it should work! However if you were designing a system that could apply MCAS repeatedly, then unwinding trim would be the first step. Otherwise there would be a high probability of ending up in an irreversible nose-down trim situation, following a series of repeated nose up elevator inputs (even with a functioning AOA sensor). Even the greenest system engineer or programmer would have picked up that issue, though not the more subtle case of stuck AOA data (which everyone focuses on).

It seems likely that most of these documents are under legal lock-down, so we may not know the truth for some time. Equally likely is that when the revised MCAS is certified, the details will be better documented. Either way, there will probably be some degree of training implications.
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