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Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

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Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#41

Post by stingraycharles »

salawat wrote: post #5

>A cynical man could be inclined to think that with this change, they casually removed a possibility of pilots/airlines realizing the existence of MCAS: "we have thrown off the right switch to unlink the autopilot from the trim motor and there is still something making automated stabilizer inputs, what could it be?" It's worse actually. They've taken a procedure, and are raising it on a pedestal as if to say "See, th…

It's fair to recognize this is not entirely Boeing's fault either: it was the airline industries that don't want to re-train their pilots and wanted this type of plane (American Airlines was specifically keen on getting Boeing to manufacture this plane [1]), so they were kind of told "we want you to make exactly $this, otherwise we switch to Airbus".

[1] https://www.vox.com/2019/4/5/18296646/boeing-737-max-mcas-so...

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#42

Post by jeremyjh »

CamperBob2 wrote: post #15
leetrout wrote: post #3

It has been fascinating to watch layer after layer peel back around all of this. Bad design decisions forced from chasing the bottom dollar, optional, critical safety features with the warning indicator and now these switches. > Boeing declined to detail the specific functionality of the two switches That's also interesting- I assume they are in CYA mode and wouldn't discuss anything that could be sensitive to the cu…

Boeing declined to detail the specific functionality of the two switches It seems like that's really the crux of the problem. They made changes that they didn't feel it was necessary to tell their customers about. Just another step along the "I know you bought this product from us, but it's still our product at the end of the day" timeline that we're stuck on. Further, I'll bet that it transpires that no one entity i…

When a culture becomes this defective, the top people need to end their careers in disgrace. This provides the necessary context, clearance and incentives for others to pick up the pieces and make substantial reforms.

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#43

Post by erentz »

djsumdog wrote: post #28

What is the endgame now for 737 MAX planes? Every airline using them has had several weeks to totally reorganize to deal with these huge missing parts of their fleets. Boeing keeps talking about fixing them and putting them back in the air, but I dunno. At this point, it should be agreed the fundamental design flaws are serious, and Boeing should have simply made a brand new plane, with much more modern controls and…

> What is the endgame now for 737 MAX planes?

The bugs will be addressed and they'll still fly. Airlines have no choice, there's a limited capacity in the world for airplane construction, several thousands of orders on the books for the 737 and 320 waiting to be filled. What can an airline do? They can cut back some orders but not all orders.

> I'd honestly like to see the 737 MAX taken out of service and Boeing simply ending this line.

I have an alternate history fantasy where instead of going with the MAX and then trying to kill the C-series as they did, they instead bought into the C-series. Swapping the cockpit for a Boeing cockpit design. Built the -500 stretch of the C-series, and then used the C-series to replace the 737 line in the <165 pax market. And moved ahead on the 797/NMA for which they'd have a shorter version covering the 200-270 pax market as a pure passenger mover as it's proposed.

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#44

Post by mcsoft »

techslave wrote: post #27
mcsoft wrote: post #20

It strikes me how a seemingly insignificant decision at the time - to position fuselage slightly higher above the ground - gave Airbus a strategic advantage 50 years later. It forced the competitor into a services of unexplainable and reckless decisions that break basic principles of reliable engineering. Which in turn led to a very visible disastrous business consequences: Boeing had to silently reduce 737 MAX produ…

basic principles? i think that’s a bit far. the plane isn’t inherently unstable is it? i thought it’s just the black box of MCAS that is the problem and MCAS is there to avoid a lengthy type certification. it’s completely explainable. and it wasn’t seemingly insignificant. it was for fuel efficiency. it was significant and they knew what they were doing.

They had to install MCAS because the plane was unstable in high AoA mode, i.e. during takeoff.

And it was unstable because larger CFM engines could not fit under the wing anymore so they had to put it further forward and a bit up. This increased the pitch up moment when a full power is applied.

Also, can't really see how the height of the fuselage above the ground affects fuel efficiency.

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#45

Post by rootusrootus »

bumby wrote: post #29
rootusrootus wrote: post #21

Earlier quoted context omitted.

But at least one aircrew in the real world actually succeeded.

True, but this seems to sound like, "if we just hire the right people none of these safety procedures would be necessary". If we only had ethical people we wouldn't need laws. Its more important to focus on the processes rather than the individual people, especially because even great people can have off days.

My point was that we should figure out why one aircrew worked it out, and one did not. If we want to fix the process, we have to consider the humans. I get the impression from this whole debacle that one significant contributor to the accidents was that Boeing's idea of what the procedures should be and what pilots actually do is different enough to be catastrophic. Putting everything else aside for a moment, this has to be a lesson about how procedures are designed and documented. It does no good to decree how something should work if the operators won't, as a practical matter, ever follow those instructions.

Edit: This seems to be unpopular. I am curious how you guys would do it differently? Just document the controls and provide no procedural recommendations? Interesting.

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#46

Post by massysett »

djsumdog wrote: post #28

What is the endgame now for 737 MAX planes? Every airline using them has had several weeks to totally reorganize to deal with these huge missing parts of their fleets. Boeing keeps talking about fixing them and putting them back in the air, but I dunno. At this point, it should be agreed the fundamental design flaws are serious, and Boeing should have simply made a brand new plane, with much more modern controls and…

These planes cost at least $100 million each. They will fix them and get them flying again.

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#47

Post by staunch »

djsumdog wrote: post #28

What is the endgame now for 737 MAX planes? Every airline using them has had several weeks to totally reorganize to deal with these huge missing parts of their fleets. Boeing keeps talking about fixing them and putting them back in the air, but I dunno. At this point, it should be agreed the fundamental design flaws are serious, and Boeing should have simply made a brand new plane, with much more modern controls and…

Now imagine if Boeing had created a brand new design instead of the 737 MAX and it had some mysterious fatal flaw as well? Second System Syndrome is something every engineer should understand. There's just no good reason to suspect a brand new design would've been bug free or easier to debug than the 737 MAX.

The 787s or A320neos could start dropping out of the sky at any minute. Maybe their carbon fiber panels start disintegrating midair after some number of pressurization cycles. The 787s almost did drop out of the sky due to battery problems. Because of the complexity involved, the only hard proof of an aircraft's safety is many years of successful flying.

Other planes have had fatal flaws that took a lot more work to discover. The silver lining of the 737 MAX's MCAS problem seems to be that it is at least quite straightforward to fix, as far as aircraft bugs go.

IMHO Boeing should payout millions for each death they caused, fix the mistakes that caused them, reorient their culture towards safety first, and return the 737 MAX to service. If they work very hard and learn from this mistake there's no reason to think they can't regain the public's trust within a few years.

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#49

Post by skybrian »

djsumdog wrote: post #28

What is the endgame now for 737 MAX planes? Every airline using them has had several weeks to totally reorganize to deal with these huge missing parts of their fleets. Boeing keeps talking about fixing them and putting them back in the air, but I dunno. At this point, it should be agreed the fundamental design flaws are serious, and Boeing should have simply made a brand new plane, with much more modern controls and…

It's rather weird to ask a huge number of mostly-good airplanes to be thrown away for PR reasons, rather than fixing them.

(Not to mention that these planes have never crashed in most countries, even with an admittedly serious bug.)

Re: Boeing altered key switches in 737 MAX cockpit limiting ability to shut off MCAS

#50

Post by dsfyu404ed »

skybrian wrote: post #49
djsumdog wrote: post #28

What is the endgame now for 737 MAX planes? Every airline using them has had several weeks to totally reorganize to deal with these huge missing parts of their fleets. Boeing keeps talking about fixing them and putting them back in the air, but I dunno. At this point, it should be agreed the fundamental design flaws are serious, and Boeing should have simply made a brand new plane, with much more modern controls and…

It's rather weird to ask a huge number of mostly-good airplanes to be thrown away for PR reasons, rather than fixing them. (Not to mention that these planes have never crashed in most countries, even with an admittedly serious bug.)

>It's rather weird to ask a huge number of mostly-good airplanes to be thrown away for PR reasons

Welcome to the internet where other people's money doesn't matter.

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