Originally Posted by
Water pilot
It is a bit odd to be blaming an aircrew in Ethiopia for not providing information that Boeing engineering already knew! Airline pilots are not supposed to be the testing and documentation department.
This really goes to the fact that Boeing chose not to document the existence of the MCAS system. The behavior that the pilots experienced was impossible in the NG so they used their best guess as to the cause, and as humans do, filtered out information that was irrelevant to the cause. After all, their job is to get from A to B and they are not trained in the art of system diagnosis and documentation. In fact, everything I have read here indicates that pilots are explicitly discouraged from failure diagnosis, which is the justification for why the function of the two cutout switches was changed. To now blame the pilots for an inadequate description of the failure seems contradictory.
The unreported stick shaker was on the penultimate Lion Air flight, not Ethiopian.
Given that that aircrews are discouraged from failure diagnoses it would have been better to report 'what happened' rather than speculate on system/cause "sts running backward", would have been much better logged as "recurring uncommanded severe nose down trim requiring use of trim cutout switches"
Anyone with tech support experience has likely had experience with a user who describes what is happening in terms of their guess as to cause rather than observed behavior. Not to say that a guess on cause is not useful at times but it should be distinct from the symptom report.
BTW: In much of the aviation world (outside USA) "engineer" refers to an aircraft mechanic, not someone who designs airplanes, not sure if this could have influenced your statement re providing information to Boeing Engineering.
Another thought is that had the broken (not an option) AOA disagree warning been functional on the penultimate Lion Air it would have likely been logged and also triggered maintenance rechecking of AOA sensors.
This annoys me everytime I see a spokesperson stating that it likely would not have affected the outcome, arguably possibly true for the accident flights but not the prior Lion Air flight.