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Preliminary conclusion MCAS misfired in Ethiopian's 737 max crash

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Re: Preliminary conclusion MCAS misfired in Ethiopian's 737 max crash

#81

Post by ams6110 »

petilon wrote: post #78
zaxomi wrote: post #22

Earlier quoted context omitted.

No, it is not unstable without MCAS. MCAS is only designed to change the trim if the airplane is hand flown in flaps-retracted, low-speed, nose-up flight. This is something almost everyone is missing: A normal flight should not encounter this.

>> A normal flight should not encounter this. What is your source? This is not what I have been reading. What I have been reading is that the MAX has a bigger engine and this engine has been positioned forward on the wing in order to preserve ground clearance. As a result of this unusual engine position, the MAX has a tendency to pitch up during acceleration. Nowhere did I read that this doesn't happen during normal…

MCAS only operates at high angles of attack, higher than normal flight would encounter. The reason it was even a factor in these crashes was the bad AoA sensor readings. If the AoA data had been correct, MCAS would not have been changing the trim.

Re: Preliminary conclusion MCAS misfired in Ethiopian's 737 max crash

#82

Post by bunderbunder »

saiya-jin wrote: post #61
yg6ht5 wrote: post #39

Earlier quoted context omitted.

$1M sounds like pocket change after all that has happened.

If those victims would be primarily from western country, especially US, there would be almost immediate class action lawsuit against Boeing from families (US citizens seem more trigger-happy to fire lawsuits when feeling wronged, at least from my perspective). But I guess Ethiopian/Indonesian cries for some sort of compensation/justice would have to go very viral in western media to force a corporation like Boeing i…

Most countries don't have such a thing as class action, and even among the countries that have it, it's only commonly used in the one that invented the idea, and multi-national class action isn't really a thing. So I think you'd find that, far from "especially in the US," you should only expect a class action lawsuit like that for a flight that is either to or from (or both) a US airport.

With lots of of passengers on both flights being from lots of different countries, what they're getting instead is lots and lots and lots of individual lawsuits all being filed in different jurisdictions.

Which is, I'm guessing, likely to be more damaging to them in the long run.

Re: Preliminary conclusion MCAS misfired in Ethiopian's 737 max crash

#83

Post by fopen64 »

chasingthewind wrote: post #76
armitron wrote: post #65

I'll never fly 737 Max. No matter what changes they do, barring a complete redesign of the plane. Boeing deserves to go out of business for this.

I'm not going to defend Boeing's conduct here for one moment, but I do think your statement is an over-reaction. The company employs 150,000 people, it contributes billions to the US economy, and builds significant aerospace know-how in the US. I imagine we could come up with lots of reasons why Boeing is a net positive. These crashes are tragic and Boeing's conduct deserves condemnation, but a solution that keeps th…

If I pack air, sell it as panacea, and employ 150k people doing that, do I deserve to be be in business?

Re: Preliminary conclusion MCAS misfired in Ethiopian's 737 max crash

#84

Post by ams6110 »

karlkatzke wrote: post #54
dba7dba wrote: post #23

Earlier quoted context omitted.

Main stream media made it sound like 40 seconds is way too short of a time to troubleshoot the issue. But now that you state it that way, I gotta agree with you it's not Only Boeings fault. Sure they are big significant part of the issue. But not the only part.

As someone who's done a bunch of human factors design training for critical situations in a previous career as a UI/UX designer and now works as a systems engineer doing a bunch of alerting, 40 seconds is too short of a time to troubleshoot the issue. When this situation happens, five things happen at once. MASTER CAUTION (whoop, whoop noises and a big red light!), ALT DISAGREE alert on the MFD, Incorrect Airspeed on…

The trim wheel always moves on the 737. It's physically connected to the stabilizer. If the stabilizer is moving, the trim wheel is moving.

Otherwise, yes I agree. A lot of stuff probably went crazy in a short time for them.

Re: Preliminary conclusion MCAS misfired in Ethiopian's 737 max crash

#85

Post by VBprogrammer »

karlkatzke wrote: post #54
dba7dba wrote: post #23

Earlier quoted context omitted.

Main stream media made it sound like 40 seconds is way too short of a time to troubleshoot the issue. But now that you state it that way, I gotta agree with you it's not Only Boeings fault. Sure they are big significant part of the issue. But not the only part.

As someone who's done a bunch of human factors design training for critical situations in a previous career as a UI/UX designer and now works as a systems engineer doing a bunch of alerting, 40 seconds is too short of a time to troubleshoot the issue. When this situation happens, five things happen at once. MASTER CAUTION (whoop, whoop noises and a big red light!), ALT DISAGREE alert on the MFD, Incorrect Airspeed on…

The fix for the problem is that it can no longer repeatedly drive the trim to it's extremes. There should be plenty of elevator authority counter a single trim movement of 2.5 units.

I appreciate your point about all of the alerts going off however the pilot is manually flying the aircraft at this point, they should feel that something is going on through the controls and react to that firstly. Imagine having a blow-out in a fancy car with pressure sensors, sure lots of alerts are going off but you have probably not registered that because keeping the car going in a straight line is taking 100% of your attention.

Re: Preliminary conclusion MCAS misfired in Ethiopian's 737 max crash

#86

Post by VBprogrammer »

ams6110 wrote: post #64
ricardobeat wrote: post #25

Earlier quoted context omitted.

Going from previous discussion, apparently it would be hard for pilots to recognise it as trim runaway. The last description mentions: stall warning going off, column shake, incorrect airspeed (on one side, due to the faulty sensor), trim wheel doesn’t move, plus the fact MCAS operates in 10s intervals. Has the information disclosed to pilots after the LyonAir incident been made public?

Yes, easy to imagine a chaotic situation causing distraction, or hyper focus on the wrong thing, etc. What I have gathered from reading other forums about this, many pilots say they would interpret any significant undesired trim as a runaway condition, regardless of whether it was happening in intervals or it was literally continuous. Others say that depending on training, and the policies of the operator, a much mor…

> I'm wondering if there's not a deeper problem within the air data systems. ... Because the stick shakers, unreliable air speed, and everything else would still be happening regardless of MCAS.

This is a very good point. If the AoA sensor failed say climbing through cloud at 5000ft on auto-pilot, dropping control of the aircraft to a pilot who's busy thinking about what he's going to have for lunch, with half a dozen alerts going off, an AF447 type incident could easily happen MCAS or no MCAS.

Re: Preliminary conclusion MCAS misfired in Ethiopian's 737 max crash

#87

Post by ams6110 »

VBprogrammer wrote: post #85
karlkatzke wrote: post #54

Earlier quoted context omitted.

As someone who's done a bunch of human factors design training for critical situations in a previous career as a UI/UX designer and now works as a systems engineer doing a bunch of alerting, 40 seconds is too short of a time to troubleshoot the issue. When this situation happens, five things happen at once. MASTER CAUTION (whoop, whoop noises and a big red light!), ALT DISAGREE alert on the MFD, Incorrect Airspeed on…

The fix for the problem is that it can no longer repeatedly drive the trim to it's extremes. There should be plenty of elevator authority counter a single trim movement of 2.5 units. I appreciate your point about all of the alerts going off however the pilot is manually flying the aircraft at this point, they should feel that something is going on through the controls and react to that firstly. Imagine having a blow-…

Good point, and that's why there are two pilots. When stuff goes crazy, one flies the plane, the other one runs the checklists.

Re: Preliminary conclusion MCAS misfired in Ethiopian's 737 max crash

#88

Post by petilon »

ams6110 wrote: post #81
petilon wrote: post #78

Earlier quoted context omitted.

>> A normal flight should not encounter this. What is your source? This is not what I have been reading. What I have been reading is that the MAX has a bigger engine and this engine has been positioned forward on the wing in order to preserve ground clearance. As a result of this unusual engine position, the MAX has a tendency to pitch up during acceleration. Nowhere did I read that this doesn't happen during normal…

MCAS only operates at high angles of attack, higher than normal flight would encounter. The reason it was even a factor in these crashes was the bad AoA sensor readings. If the AoA data had been correct, MCAS would not have been changing the trim.

When an aircraft pitches up, it increases the angle of attack, right? (If not MCAS would not be a fix for the pitching up problem.) And the pitching up can happen during normal flights, correct?

Re: Preliminary conclusion MCAS misfired in Ethiopian's 737 max crash

#89

Post by mannykannot »

tyingq wrote: post #27
sokoloff wrote: post #20

Earlier quoted context omitted.

40 seconds is an eternity to accomplish the memory items on runaway stab trim non-normal checklist. It’s literally “control column - hold firmly” (already a given, since MCAS only affects manual flight and the increased back pressure required is the cue that something is amiss), “autopilot and autothrottle - disengage” (click-click, click-click), (if runaway continues) “stab trim cutout switches - cutout (both)”, (if…

The layperson in me wants to know why things like trim don't have a meter/display that shows the actual setting. Seeing +6/-6 seems like it might trigger recognition of runaway adjustment.

Over a period of six minutes, the captain repeatedly (at least 25 times) re-trimmed nose up. If that does not say trim runaway, I don't think a meter would make a difference.

Re: Preliminary conclusion MCAS misfired in Ethiopian's 737 max crash

#90

Post by salex89 »

fopen64 wrote: post #83
chasingthewind wrote: post #76

Earlier quoted context omitted.

I'm not going to defend Boeing's conduct here for one moment, but I do think your statement is an over-reaction. The company employs 150,000 people, it contributes billions to the US economy, and builds significant aerospace know-how in the US. I imagine we could come up with lots of reasons why Boeing is a net positive. These crashes are tragic and Boeing's conduct deserves condemnation, but a solution that keeps th…

If I pack air, sell it as panacea, and employ 150k people doing that, do I deserve to be be in business?

If you can actually pay 150k people, maybe you do, since you're bloody good at it!

Joke aside, let's be fair, Boeing did not sell air. Their greed got the better of them, and the institutions set to prevent that did not do their job. They should take responsibility for the things they did (or in this case, did not). There is no penalty high enough to bring back lives.

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