They turned the switches back on because they physically couldn’t move the trim wheels, and the only thing holding the nose up was the pendulum effect of the thrust of the motors.

It’s a **** poor design of a transport category airplane that at this juncture, is too big to fail.

 

Having flown 737 NG with manual stab trim after stab out of trim light on at 15,000’ I can say this.

At 250 kias forward manual trim was easy and smooth operating. Nose up trim was difficult and was not smooth.

It would have been extremely difficult/impossible to get ANY manual nose up trim at the 400 plus kias that they were at.

I would like a no look scenario in the sim.

Something no one has mentioned. MCAS is only active after flaps up. I would consider extending flaps to 1 if cut out switches proved to be ineffective. That being said, is it a function of flap position or flap handle position??

 

Air Ethiopia FO Ahmed Nur Mohammod Nur, 25, was an airline flight academy graduate with 361 flight hours logged, including 207 hours on the Boeing 737.

 

Some 737 manuals used to discuss the push-pull roller coaster technique at high loads. Push to unload while manually trimming up, pull no later than hitting the ground, repeat.

 

Absolutely. Maybe on a vanilla go-around before flaps are up. No brief, no notice. Train to proficiency but log the first look results.

 

I think that a number of people at Boeing should be investigated for actions that violate our criminal justice code.

The whole board, and all of upper management should have already resigned...

https://www.theatlantic.com/ideas/ar...arings/602188/

https://theoutline.com/post/8269/the...=1&zi=h47uyaim

https://www.ccn.com/10-blunders-that...7-max-forever/

 

I was hoping that Boeing would have stopped at the max 9 after the crisis and either built a new airplane or revamp the 757.
I just saw the other day they are rolling out the dash 10 abomination.
They have learned nothing from this debacle except to continue profits over safety and common sense. New management is needed desperately!
Boeing use to build magnificent airplanes but haven’t since the 777.
Although the 787 is good now it had a rough start and because of outsourcing and profits over safety they were lucky they didn’t have a hull loss.

 

They did not cut out the stab trim until the trim position was nearly full nose-down and was flying at over Vmo (over 390kts vs Vmo of 340kts). When they turned the stab trim back on the captain repeatedly tried to engage the autopilot (which won't engage when out-of-trim) instead of using the primary electric trim, which might have had a chance of rolling the trim back up. That allowed additional unscheduled MCAS activations to roll it to the full nose-down stop.

The Captain didn't know what to do so he kept trying to engage the autopilot. He had tried the same thing less than 500' off the ground on takeoff (minimum autopilot engagement altitude on takeoff is 800'). In doing so, he briefly coupled the autopilot (CMD A) to the Flight Control Computer that was receiving bad data. This produced unstable pitch inputs from the autopilot and caused the autopilot to disconnect within 30 seconds.

While "STAB TRIM CUTOUT switches ... CUTOUT" is part of the applicable procedure, they did it far too late and without doing the previous steps--this one is the second-to-last step. Doing only one item on a checklist does not qualify as following the procedure.

They made many other procedural errors prior to that one including never just flying the airplane. i.e. when the nose gets heavy, trimming it back up with the primary electric trim. The Captain of the Lion Air accident flight kept the airplane in-trim through 21 unscheduled MCAS activations by doing just that. The trim didn't get significantly out-of-trim until he transferred control to the F/O who did not re-trim the airplane after each MCAS activation.

If you're interested in understanding the actions of both accidents crews, I'd recommend this (rather long) article from NY Times Magazine. It is the most detailed article that I have seen on the MAX crashes.

https://www.nytimes.com/2019/09/18/m...x-crashes.html

 

That article is the best explanation that I have found as well. Only one question. The 800’ autopilot engagement altitude is company imposed. It used to be 1,000’. Any idea what the actual Boeing limit is?

 

500' (unofficial source - assuming NG limit is same as MAX)

Boeing 737 Limitations