Originally Posted by ExplorerWannabe (Post 30964002)

The reports are that it kept nosediving even with MCAS turned off so it's not the software. The engineering analysis quoted earlier indicated qualities that are contrapositive to nosediving early in flight so what caused the nosediving in the first place and kept it going while the electrics (including MCAS) were turned off?

Originally Posted by mduell (Post 30964531)

Some really selective reading going on here. Where in the Boeing procedure does it say to turn the electric trim back on and not command it in the direction you want?

Originally Posted by danielSuper (Post 30964568)

Right under "two bodybuilders with four hands and a cane to block trim wheel are required to safely operate this new airplane"

Originally Posted by mduell (Post 30964606)

More selective reading. No effort with electric trim on, you've just got to use the controls.

Originally Posted by ExplorerWannabe (Post 30927563)

A lot of this reminds me of the "discussion" after the Apollo 1 fire. Borman's testimony seems particularly apt (recreated in "From the Earth to the Moon" at https://www.youtube.com/watch?v=ZqaBYoElHVg). I very much doubt Boeing or Ethiopian or even Lion Air intentionally compromised safety. IANAP but Boeing likely didn't imagine flight crews at a major airline would ignore or not know of procedures that seem to have been "standard" for decades. In my own job as a "subject matter expert" in a particularly isolated field, I am still constantly amazed at how lessons learned 25-30 years ago are "magic" today or how practices I once accepted as the norm are now abnormal (to be fair, this is sometimes a good thing).

Nevertheless, the OP's question was more strategic, should UA change aircraft? I would still say no for a variety of reasons (not even counting my own admitted bias against Airbus).

https://www.flyertalk.com/forum/unit...r-a321neo.html


If United's 737 pilots are still confident in the 737 fleet, I'm confident.

Originally Posted by ExplorerWannabe (Post 30964002)

Nothing in today's report that we didn't know yesterday and again ... WHY WAS THE PLANE NOSEDIVING?

The reports are that it kept nosediving even with MCAS turned off so it's not the software. The engineering analysis quoted earlier indicated qualities that are contrapositive to nosediving early in flight so what caused the nosediving in the first place and kept it going while the electrics (including MCAS) were turned off?
I am sure that unexlained nosediving with only 1000 feet altitude would cause panic. That's not a lot of time or altitude to come up with a solution. On the other hand, the charges that the design is deadly, that Boeing or employees are guilty of criminal conduct just are not supported by the evidence released so far. The basic 737 design and construction has been well-proven with tens of thousands of flights. The design qualities in the MAX that reportedly prompted the MCAS software should actually have mitigated this scenario when MCAS was turned off so what happened? Is it a different design defect in the aircraft? Perhaps Boeing did something else wrong in the design or construction and the furor about MCAS is hiding it. Was there an overlooked maintenance issue? (yes, I know Ethiopia brandished the recent certificate but the fact remains that very aircraft had a similar incident recently and IIRC there were other reported maintenance issues on it). Was there something else wrong in the launch configuration?

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Originally Posted by LarryJ (Post 30964353)

The answer can be found in the DFDR data that we have from the Lion Air accident flight.

The Lion Air Captain kept the airplane in-trim ("no nose diving" in media-speak) by using the primary electric trim to stop each MCAS activation and return the stabilizer to an in-trim condition. He did this 21 times over a period of several minutes.

When control was transferred to the First Officer, the F/O used the electric trim to stop the next four MCAS activations but he didn't continue to use it to remove the nose-down trim that the MCAS had input as had the Captain. Each subsequent MCAS activation progressively moved the stab trim farther and farther nose-down. He didn't stop the fifth, and last, MCAS activation and that allowed MCAS to run the stab trim to the full nose-down position (the state in which the stab jackscrew was found).

When you do the stabilizer runaway procedure, and flip the stab trim switches to cutout, it stops all electric stab trim inputs which stops the stabilizer in its current position. If you do this when the stab is at, or near, the full nose-down position you will have a real problem on your hands as you try to maintain control while manually trimming the stabilizer back up with the trim wheels. If you have been keeping the stabilizer close to in-trim, as the Lion Air Captain did, then when you cutout the electric trim it will be relatively easy to keep it in-trim with the manual trim.

Originally Posted by rdchen (Post 30964860)

So if the ET pilots first used the thumb trim switch to counter the malfunctioning​​​​​​ MCAS, then cutoff the electric trim switches, the end result might be different?

Originally Posted by rdchen (Post 30964860)

So if the ET pilots first used the thumb trim switch to counter the malfunctioning​​​​​​ MCAS, then cutoff the electric trim switches, the end result might be different?

Originally Posted by LarryJ (Post 30965538)

That's how I would do it and is consistent with the information contained in today's preliminary report.

Originally Posted by DenverBrian (Post 30965681)

Boeing finally, finally, moves in front with this apology and admission of responsibility.

https://www.usatoday.com/story/news/...ng/3361880002/