Boeing 737 Max design error

If you know the plane if flying at 300 MPH and is in a level or close to level attitude, has been that way for X seconds, you can definitively rule out a stall. And more fundamentally, to address your concerns, MCAS will now use BOTH AOA sensors and if they disagree, take no action.

I wouldn't argue with that.

What aircraft are (or have you been) qualified to fly?

Have you come across the concept and practice of "mushing"? As in...

Been there, done that.

BTW, Wolfgang Langewiesche's "Stick and Rudder; An Explanation of the Art of Flying" is /well/ worth reading several times.

Bro you act like you're brand new and don't know how huge corps like Boeing operate. Here's my citation. I use my brain to think of whatever slimy, underhanded way the 60 and 70-something sociopathic baby-boomer executives of the company could come up with to shirk liability and prevent any risk of damage to the company's profits or share prices.

If what seems most apropos and expedient would seem to be covering up a software fault and instead blaming the filthy African pilots via a concocted PR story they believe much of the American public will accept due to that public's intrinsic racial bias then that's what they'll plan to do. 99% probability.

And US carriers

Their margin on this one ain't gonna be made by selling just to the what, three or so, domestic major carriers left.

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Thank you for the admission that you just made up your accusations.

They're not accusations they didn't do any such thing, or at least aren't right now. Can't, not with two crashes with what look like similar root causes.

If it had just been one in Africa we likely wouldn't be here having this pleasant discussion.

Mushing has nothing to do with what I stated. Explain to us how a 737 that's been going 300 MPH in level flight for 30 seconds can be stalling. It can't.

Every aircraft I have flown and owned changes pitch with power and flaps. You simply know it's going to happen and expect it and make the necessary trim corrections automatically. That's what the trim control switch on the yolk is for.

There is no need for an automatic trim system like MCAS, especially when it is undocumented.

In the case of the Ethiopian crash, the solution would have been to turn the electric trim back on, while holding the trim up button in. It looks like in the seconds before the crash, they did turn it back on and MCAS pushed nose down again. No evidence if they were pushing the trim up button at the time. Or what happens if the pilots are commanding trim up while MCAS is doing trim down, ie who wins or if nothing happens. The even better procedure would have been to use the up trim button to first get the trim back to near neutral and only then turn off the trim switches.

Interesting that it's so difficult to manually trim with full trim and speed. It also apparently takes some time winding the wheel, it's many turns. I watched a video of it being done in a simulator. One pilot spent most of his time adjusting the trim, as needed, while they did a return and landed. Also interesting, with the LA flight the day before the crash, when they had the same problem and the jump seat pilot had to tell the actual pilots what to do, they then continued on to their destination, using manual trim. Must be different standards over there, in the US the plane would have returned to the airport, for a variety of reasons, including that you're not sure what exactly is wrong or going on.

+1

And we had at least 4 out of 7 pilots who couldn't, which is stunning.

two on LA flight the previous day two on the LA crash

The one who definitely got it right was the LA jump seat pilot

The pilot on Ethiopia we really don't know

The co-pilot on Ethiopia with 200 hours correctly identified it and was following the procedure, but the trim may have been too nose down and the plane going so fast that he couldn't wind it back manually. It would have been much better to use the trim buttons to get it near neutral to up somewhat and only then turn it off and go manual. And it looks like that might have been what he or the pilot decided to do, because someone turned it back on. But MCAS then shoved it down again. Did anyone have their finger on the trim up? Has anyone tested this in a plane or simulator?

It kind of works that way anyway. MCAS is not active with flaps deployed which is generally what you're going to have at low altitudes. That's why with all three of these flights, the trouble started just as the flaps were retracted. You would think that if they couldn't figure out what was going on, one of them might have thought that since the problem started with flaps zero, maybe they should try deploying flaps again?

It will. And so far, Boeing's response has been pretty poor, IMO. No acknowledgment that they screwed up badly with a design that never should have left the drawing board.

I'd say a truck driver doesn't need to know how ABS *works* in detail, but they need to know it's there and how to work with it. For example, you need to know what ABS is intended to do and that when it's active, with the peddle pulsing, you should maintain steady pressure and not try to pump it yourself. With MCAS, the first pilots didn't even know it was there. But the second ones did and they knew of the previous crash and it still turned out the same. Doesn't leave me with a lot of confidence in pilots, at least foreign ones in dubious countries.

And yet in all the reporting, all the discussion, that is rarely, if ever mentioned. Why is it that we've heard nothing about the root cause of the AOA failure? Was it actually traced for sure to the AOA itself, as opposed to wiring, interface circuit, software, etc? You would think there would be something like there typically is after a crash like this, where they call for inspections or replacement, etc. But here nothing. And these were brand new sensors. Also what went on at Lion Air as they tried to fix it? Supposedly they put in a replacement sensor. So, how did it fail again or did they replace the wrong one? And there were reports on the planes that crashed as well as on the flight from the previous day of airspeed disagreeing between the pilot and co-pilot displays, maybe altitude display issues too. If it's just this AOA, how is it affecting airspeed? One of the flights, I think the airspeed was off by like 40 MPH from one side to the other.

No it's not. I'm not talking about training for MCAS, I'm talking about training that all pilots go through to get qualified and to continue to be employed. That's where they would have been trained on how to deal with runaway trim. And from what we know now, at least

4 out of 7 pilots couldn't deal with it, despite that it's supposed to be a memory item.

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ion is not so simple to diagnose as was initially indicated. When you have a cockpit full of instruments and controls and "something" is wrong and th e plane is behaving very erratically, it seems not so simple to do the righ t thing and know that it was right in the face of the airplane continuing t o fly improperly.

It is simple. The trim wheels are spinning right next to your leg. Something is pushing it way nose down. You push it back up with the trim button. Five seconds later, *something* is pushing it back down again. How hard is it to identify that as a problem with the electric trim? That the plane can;t fly with full nose down trim, but it flies every other day with small trim? Hello? It doesn't matter what is causing the electric trim motor to turn and do something abnormal. It could be a stuck switch, a short, it doesn't matter that it was MCAS. And the procedure is to turn it off using the switches right above the trim wheels and then trim manuall y. We know it works, because that's what the pilots on LA did the day before. This is very, very basic flight principles and training that is supposed to be committed to memory, precisely because in an emergency, with runaway trim, you have to do the right thing and do it quickly.

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I agree it's too early to make final judgments, but there is plenty out there already to make some judgments, including that the pilots bear some of the blame. It's similar to most of these, which is why crashes are so rare. It's rarely just one thing, it's a whole series of things that have to go wrong for it to result in a crash, all of them low probability. Speaking of probabilities, I'm still mystified as to why there has been nothing about the root cause of the incorrect AOA reading. You'd think they would have said, we think it was a manufacturing defect, incorrect installation, damage to it, etc. And then some kind of order to inspect, replace, etc. But so far, nothing that I've heard. Which makes me wonder, are they sure it's the AOA and not something else, eg software bug?

have been prevented by using pilots to write code. lol

That makes no sense to me. We'd never get software for many of the complex systems out there if one had to actually be a user of one to write the code. Space rocket code, you have to be an astronaut? Code for a nuclear sub, you have to be a nuke reactor operator or sub capta in?

stem go so wrong that so many people died in two accidents. This investiga tion should be no less rigorous than the investigation into the Challenger accident.

Sadly with the Ethiopians and Indonesians driving it and controlling it, that probably isn't going to happen.

Well that's a lie. It doesn't cost more to develop a whole new plane as opposed to modifying an existing design? Training and certification on a new aircraft type doesn't cost money? Having some pilots that are certified for one, but not the other, doesn't limit who's available to fly a plane? Some airlines don't chose to limit the variants they fly so that parts are the same, maintenance training is the same, etc?

If that's the case, then why does MCAS force the nose down at high angle of attack without regard to whether the throttles are advanced or not?

Well, make up your mind. And it's not irrelevant because the other poster claimed that

"Do you want to fly a plane that only software is used to prevent stalling? Without software it stalls."

So whether it really stalls without software under most conditions or the software was only added for very high AOA conditions that a plane would never experience except for some very rare, extreme conditions that it should never see in passenger service, is relevant.

I would disagree. A 737 max is no more likely to wind up in that high AOA position. It has to be some extreme flying, not a typical passenger flight to get it there. And only then does the Max have a tendency to stall easier.

That's true, but it's at the margins of operation, not what passenger planes see every day.

There apparently can be if you want to get the plane CERTIFIED to fly under the same type rating, which was a prime objective. Would FAA certify it if it knew that at high AOA it behaves differently and differently not in a good way?

everything I've read says that the MCAS with pause for 10 seconds if the pilots command trim up, though it might be confusing that the problem goes away only to come back 10 seconds later

since you can override the electric trim by grabbing a trim wheel and holding it I assume there must be some kind of clutch limiting the electric trim force to less than you can hold by hand, which lead to the question; if the force needed to trim up is so high you can hardly move the trim wheel won't the electric trim be useless as well?

I've asked on a few of the youtube videos done by pilots but never got an answer

Not exactly. The VW people deliberately designed in specific cheats. The Boeing thing was a mistake followed by some poor judgement.

Sounds like diesel sales are way down in Europe. Lots of big mistakes were made.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

Agree. I'm not sure on the 10 secs, thought it might be 5, but you're probably right and it's basically the same, MCAS comes back quickly.

IDK, but I had thought about the same thing, that part of the runaway trim procedure is that you can hold the trim wheel to overcome it, so how is that done?

Very good question, but obviously the electric does still work, because on these flights they were able to keep bringing trim back up and MCAS was able to push it down. How you reconcile those, IDK. Also, if it really was impossible for that Ethiopian co-pilot to turn the trim wheel, seems there is more wrong there than just MCAS. It would imply that on any 737, if you have a runaway trim and it goes to hard trim in either direction, you may not be able to counter it by the stated trim procedure.

Also, I think a step is missing in the runaway trim procedure. After identifying runaway trim, the procedure should be to see if you can use the trim button to get the trim back to near neutral and then turn off the switches. If you can get it close to neutral that way, that's going to be a lot faster than winding it by hand. That might have been what the Ethiopian pilot was trying to do in the last seconds. But we don't know much, they haven't released the voice recorder or anything that shows what, if anything they were saying at that point. The authorities only quoted the co-pilot saying he was going to trim manually and that he couldn't, not that he couldn't turn the *wheel* for example. It's even possible he was confused and was referring to the trim buttons on the controls, which of course would not work because the switches were off. Also quite surprising that from what they released there was very little crew management and discussion. Like the switches got turned back on, but apparently no words informing the other pilot, etc.

Someone must know the answer.

Why would engineers be expected to push back? This wasn't some after thought. Boeing decided they wanted a plane based on the existing

737 for a variety of reasons, including that it was an obvious advantage to it;s customers and in turn, to Boeing, because no new training would be required. And for it's customers, it's a very similar plane to operate and maintain. If they had come up with a new design, then the pilots would not just need additional training, they would need a type rating for the new aircraft. All that entails very real time and costs. And with MCAS, by all indications it did behave the same way, unless MCAS failed and even that is no different than a similar runaway trim condition, which all pilots are supposed to have committed to memory.

Apples and Oranges. VW deliberately cheated and broke the law. They designed a cheat around testing in the cars, something that was not needed, was not used, except when the car detected that it was being EPA tested. Boeing had a very reasonable design goal, one that saved their customers money and time. It's just that somehow engineering and safety turned to crap and failed badly. There is no reason to believe that's anymore related to marketing than if some other fatal and bad design flaw was found in any other aircraft. Presumably Boeing didn't say to it's design team, come up with a poor, stupid MCAS design. Now, if evidence emerges that there were internal discussions about it being a bad design and marketing or management overrode it or it turns out designers argued the AOA disagree light and display needed to be standard equipment for safety and they were overridden, then it would be different.