[js2]

You can still point back to Boeing for not recommending flight simulator training of this failure scenario.

One thing that I've wondered though as I've read more about MCAS. MCAS can't kick in till the flaps are fully retracted. Usually when something goes wrong in response to an action, the response is to undo the action. Why isn't the procedure or even the pilot instinct to re-extend the flaps when the nose down occurs just after having retracting the flaps?

[msbarnett]

> One thing that I've wondered though as I've read more about MCAS. MCAS can't kick in till the flaps are fully retracted. Usually when something goes wrong in response to an action, the response is to undo the action. Why isn't the procedure or even the pilot instinct to re-extend the flaps when the nose down occurs just after having retracting the flaps?

When the two AoA sensors began to disagree during takeoff, the left and right side airspeeds started disagreeing as a result. That leads the pilots to execute the Unreliable airspeed indicator checklist memory items, which include levelling off for troubleshooting and leaving the flaps in their current configuration (retracted), and to keep thrust high to avoid stalling due to the unreliable airspeed indicators.

It's precisely at this point that MCAS now kicks in and starts nosing them down. Extending flaps will cut it back out but: 1) they're now instinctually fighting the stabilizer with elevators to stay out a nose dive, 2) the checklist they were running when this started says not to extend flaps, 3) the Boeing/FAA directive tells them to hit the STAB CUTOUT, so they do that, but 4) the elevator/stabilizer fight + the high speed from the thrust being set to climb due to the checklist they were running when this started results in so much force on the manual stabilizer crank that the co-pilot can't turn it by hand and now they're so engaged in this stabilizer fight and trying to get the plane trimmed for landing that the flaps are the last thing on their mind, and the Boeing/FAA directive never instructed them to try re-extending them, airspeed disagree be damned. They're completely out of the manual and FAA/Boeing directive at this point. Nothing covers this (anymore, 30 year manuals would have had a procedure to ease the forces on the wheel here).

So lacking any other means of trimming for landing, they turn the electronic stabilizers back on, and trim electronically, which works...but they don't cut it again within 5 seconds (the FAA/Boeing directive didn't really spell out how crucial this timing is, or even consider that manual trim would have been made impossible by everything else going on), and the MCAS runs again, and the dive becomes fatal.

[cjbprime]

There's also a lot going on at that point in flight. It's within ten seconds of autopilot, for example. Would be hard to pinpoint. Besides, they have checklists to follow: airline piloting is not supposed to be creative and experimental.

[ominous_prime]

I would guess that the node down attitude quickly put them over VFE, so even it they could extend the flaps (I don't know if the flight system would prevent that or not) they would at least second guess doing so and continue other avenues of troubleshooting.