Originally Posted by
FullWings
Scenario 1: In the simulator, doing a “runaway trim exercise”. There you are at 6,000’ straight and level, 220kts, nothing happening. Oh look, the trim has started moving on its own, can’t stop it, I wonder if this is right? No? OK, do the runaway checklist. Sim passed! Easy, this trim runaway.
Scenario 2: In the aeroplane, cleaning up. Trim starts moving forward, then stops. Is that MCAS gone wrong (or even possibly functioning correctly), is it STS doing its job or is it the other guy who’s flying it trimming the aircraft? Hmmm. There goes the trim again...
Scenario 3: All the above plus continuous stick shaker, aural warnings and UAS symptoms.
Honestly, I’m not quite sure how you would train an MCAS runaway in the sim, if disconnecting the trim when there wasn’t an actual runaway = fail. It’s easy to say “they should have done the trim runaway checklist” but how do you tell NORMAL operation of MCAS/STS from ABNORMAL in a very limited timeframe? If you disconnect the trim every time it moves, you’re going to be doing lots of very short flights...
I understand what you are trying to say, but let me make this observation.
We know that the MCAS input stops if any pilot puts in manual electric trim. It then restarts after a 5 second delay. If a pilot is regularly responding to the changing trim pressures by inputting nose up trim (MCAS trims some nose down, pilot trims some nose up, MCAS trim nose down, pilot trims nose up, repeat), then yes, it looks a lot different than a classic runaway trim.
In the case of ET302, however, the MCAS input lasted
9 continuous seconds which equates to around
37 spins of the manual trim wheel. The entire time, the Captain has the yoke in his hands and the control pressures increase dramatically. This happened at least twice. What about this does not scream runaway trim?