Originally Posted by
FullWings
I think that’s the core of the issue that divides the “pilot’s fault” crowd from the “aeroplane’s fault” one.
You’ve just got airborne in a 737 MAX and the trim starts running. What are you going to do? There are multiple reasons why the trim could activate: some benign, some not so; as above, what is the trigger for performing the runaway trim checklist? OK, so not enough information to make a rational decision at this point - it would have to be a guess, something professional pilots don’t really like to do. You could say do the checklist, just in case, but you’d be doing it on every flight. Might as well disconnect the trim *before* you take off, to be sure.
This situation is confusing enough on its own; now add in UAS, stick shake, flashing lights, noises and you have overloaded sensory channels making cognition exponentially harder. This is why Human Factors play an equal or greater role here than the purely technical ones.
Fundamentally, for some time after takeoff, abnormal operation of the trim system is virtually indistinguishable from normal operation because 737 pilots (and I have been one) get used to frequent intermittent trim operation by the aeroplane systems, to the point that you’d only notice it if it wasn’t happening, like living next to a main road.
Quite so, however, you can effectively sit back and relax at this time, we have enough information to now understand the system;
Normal operations: you get airborne, trim runs automatically for SRS....for a short period, and then stops. No other noises.... No problem enjoy your coffee.
MCAS issue as per last 2 accidents. You get airborne, and at some point you get a stall warning, Shaker, IAS/ALT disagree, and stab trim running tout suite. Use trim switches to run trim back to an in-trim case, and then Shut off the Trim. For my money, you are now unairworthy, and are going to return or divert to nearest suitable and enjoy a coffee. The aural warning is going to keep running as will the stick shaker until you take action to shut it up. If you are uncomfortable flying around without a stick shaker, then enjoy the noise. If you are OK with the fact you have, GS, ATT x 3, 2 IAS, 2 ALTM other than the one that has gone bad, then enjoy the quietness, and don't pull past buffet unless you enjoy the ride.
Broken Record: The Lion and Ethiopian crews did not have the information to hand to sort our the wheat from the chaff, in the time allotted. That doesn't make them incompetent, it makes them star crossed on the day.