Ethiopian Crash


#41

He probably called his friends, told them to short Boeing, and then made the announcement. :upside_down_face:

I suppose politics and this kind of decision are inextricable when they shouldn’t be. A strong and independent civil aviation entity should be a part of every country’s structure, and decisions should be made by them based on safety and data, not political pressure or economics. In a perfect world.


#42

That’s supposed to be every government agency, and this has been a recurring theme in my classes (Masters of Public Administration) every week. We hear a lot of, “this isn’t what’s supposed to be normal, but…”

Getting back on topic, heard this story on the situation this afternoon. Interesting bit there again about the flight manual and the AA planes.


#43

Whatever the politics, it is done. The financial losses are beyond my comprehension. Safety follows capitalism and the wheels are now turning at lightening speed. This has been a terrible week by any standard. Good people have died, people both good and bad have lost their careers and their portfolios. But now a safe jet can emerge from the process. Will the public trust it? How Boeing and the airlines manage the next month will be fascinating to watch.


#44

Ok, looks like Boeing have jumped too. The article sites ‘evidence discovered at the crash site’ but no further details. I wonder if a preliminary look at the CDR has shown something?

BBC News - Boeing grounds entire 737 Max crash aircraft fleet


#45

People are loving the 787 despite the fact that two caught fire so early in their service lives. Because Boeing identified the flaw and took steps to mitigate it that built confidence.

How many 787s have had those runaway fires since? None. I don’t know if there have been any further battery fires at all, but if there were they flew under the radar because the fire was contained to the battery and basically became a maintenance issue.

So I’d say Boeing can do it, depending on what fix is required and whether as rumored the solution would just expose a different problem.


#46

The problem here, I think, is that this is the fix for the 737-MAX. The addition of newer, heavier engines to the 737 body moved the center of gravity (mass?) farther forward than it ‘should’ be aerodynamically and that required something like the MCAS system to prevent an unfortunate potential stall … the problem seems to be that the system can not be overridden easily or pilots do not know which breakers to pull ‘in the moment’ to get control of the jet back and stop fighting the MCAS (given that 5 seconds after you override it, it is allowed to fight back).


#47

I think (and I don’t know this to be true) it is also that the root of the problem might be conflicting AOA data being sent to the airplane’s flight control system (for lack of a better word). From what I read, there are only two…so if one gets jammed, damaged, or iced up (no idea if any of those things are possible), there is not a third voting member to say - oh…this one is bad. On a system as important as one that pushes the nose over, I think it might be a good idea to have a third sensor to give the 2 out of 3 dentists recommend not doing this type of confidence…

Let me just be clear though - I know nothing about this system, and everything I wrote is probably wrong. :slight_smile:


#48

How long have the MAX 8’s been in the field?

EDIT: Just looked. Not that long. Uh-oh.


#49

One explanation might be autopilot engagement. In my 20 years on the plane I can count maybe 5 times when the Pilot Flying engaged the autopilot below 3000 feet. I usually wait until FL200 or therebouts. My other western counterparts probably behave similarly. Maybe that masked or prevented the circumstances that caused the LionAir crash. (I am not ready to lump Ethiopian yet.) As news outlets have correctly noted, many countries compensate for low flight deck experience by enforcing strict use of automation. That trend was supposed to reverse worldwide after Air France and Asiana. But the wheels of habit turn slowly.

I cannot claim the slightest understanding of MCAS other than the conflicting descriptions I have read in news feeds. Airlines and Boeing have been mum. But I do understand the trim system (the sole control used by MCAS to provide the nose down moment). It could not be more simple. Its two big wheels on either side of the throttles that turn old fashioned cables connected directly to the stabilizer. Two electric motors are bused through the same cables. Those motors allow for pilot electric actuation—moving the wheels feels a little silly in a big plane—or autopilot. There are also different trimming speeds but that is getting unnecessarily deep. The important thing is that electric trim can ALWAYS be easily cancelled by flipping the two disconnect switched next to the throttles*. So there will never be a need or an impetus for future pilots to try to “trick-fornicate” the system. A safe override already exists. The issue with MCAS has always been one of training and full honesty with the pilots flying the plane. If they had done that, then there likely would not have been a problem. And because of that, the future looks promising.

Now @BeachAV8R touched on the other problem which is a total mystery to me—the AOA input to the system. Why is it, or is…err…is it sensing a stall? Obviously in neither crash was a stall anywhere near imminent. So that’s a million dollar question.

*news outlets also claim that clicking electric trim will also stop autopilot trim. While that may be true, seconds after you let go AP trim resumes and the effects are cumulative. After a few cycles of this you will find yourself with full aft yoke and still headed for the dirt. The only effective solution is 1) AP off, 2) Stab Disconnect Engage, 3) recover with elevator and manual trim (the wheel)


#50

What is more troubling to me is that apparently one of the planes (can’t remember if it was the Lion Air or the Ethiopian one) had had the MCAS system kick in on a couple other flights prior to the fatal one. I read something along the line of - on previous flights the system had engaged and the pilots correctly handled the problem. It is odd that the plane would have not been taken out of service to examine exactly why the system was coming on.

Correction - it looks like it was addressed:

“The Lion Air plane’s angle of attack sensor had registered incorrect airspeed readings on the four flights prior to the crash, according to the Indonesia National Transportation Safety Committee, and Lion Air said the sensor had been replaced the day before.”


#51

LionAir is getting a lucky pass here. I mean, yes, they were the tragic victim of a faulty system. But through the case you mention above and many, many more, that airline has proven to be as penny-pinching and corrupt as they come. The Max shutdown is almost a vindication for them. Something they have no rights to.


#52

Mudspike is fortunate enough to have actual pilots in the membership rather than the wildly speculative folks found elsewhere on the internet. I feel like I’m getting a class in aviation.


#53

#54

Interesting take on this.


#55

I’d want to see what airlines purchased the extra AoA vane option, and who didn’t.


#56

Would MCAS inputs trigger the usual trim ‘drumroll’ that brings your attention to the fact that the trim is being changed for an unusual length of time?


#57

I would think so… but I don’t know how far trim disconnect switch it. In KC-135s, we got beaten into submission for “run away trip” malfunctions.


#58

After a Citation with a medical team crashed into Lake Michigan several years ago, it was drummed into us on the Corporate/Business aviation side too. It’s a very simple procedure in every airplane I have flown, but the malfunction seemed very obvious in most cases. It sounds to me that the MCAS issue is a bit more insidious in how it presents itself, although it seems some pilots have figured it out before losing control of the aircraft.


#59

That’s what bothers me the most, identifying this problem in time when it arises means you are on a very short deadline, and the system does not accept counter input as a communication from the pilot saying “you are wrong MCAS”. It will happily continue despite being overruled. Add to this the fact that this sensor is non-redundant and a flight stability augmentation system has “optional” hardware and the fact that this was required to gain certification?

Honestly, this whole thing is quite the mess that never should have happened. We know these things from best practices by now. To me the question is mostly ‘how did this slip by so many engineers’, and I wonder what forces have acted upon those contemplating or opposing the current implementation. I’ve heard stories of the FAA giving Boeing a free reign for about 8 years now, though the veracity of those stories are something different.


#60

The trim wheel is obnoxiously loud on the 737. By comparison, the trim my current planes: the 757 and 767 are totally silent and lack significant visual cues. This issue would much more easily sneak up on the pilots in those planes. The Airbus has a visual indication much like the 737 but is silent. So it too, if it had a similar system to MCAS (which it doesn’t) would sneak up on the crew. But trim activity in the 737 is obvious. But we must never forget that the crews were probably distracted by a series of warnings related to the faulty AOA input. They might even have had a stall warning. The human pilot brain will totally focus on the warning and totally ignore the trim. We are good at lots of stuff but multitasking is not one of them. And I wish this point was made more clearly to the public when pundits consider the failure of both crews. They were not just dealing with a plane that wanted to dive for the deck. They were also dealing with a plane that was screaming at them. It would have been a total horror show.

The speculation among pilots is that this system never need have been installed in the first place. Money and the need to make a new plane that flew closely enough to the old that no further training was required was the likely impetus behind it. And now we are learning that Boeing employees were contracted by the FAA to help with the certification process. This thing is going to go very deep and wide. Boeing and the Max will both survive because both are To Big To Fail. But both will forever be mared by this—and rightly so.