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

seattletimes.com

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

#21

Post by rootusrootus »

ricardobeat wrote: post #13
exabrial wrote: post #7

> As various warnings went off in the cockpit, they never reached the conclusion to use the runaway stabilizer procedure. We continue to put the microscope on Boeing but this is why there is a person in the cockpit: to oversee the planes automated systems. There were multiple failures, and while we pick apart Boeing, we have not done the same to the pilots.

Read up on the extensive reporting on both accidents. They never reached that conclusion because it was absolutely unexpected, as a result of Boeing’s stealth changes to the aircraft. There was an article recently where they put very experienced pilots in a simulator under the same conditions and they all failed.

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

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

#22

Post by Majromax »

exabrial wrote: post #7

> As various warnings went off in the cockpit, they never reached the conclusion to use the runaway stabilizer procedure. We continue to put the microscope on Boeing but this is why there is a person in the cockpit: to oversee the planes automated systems. There were multiple failures, and while we pick apart Boeing, we have not done the same to the pilots.

> There were multiple failures, and while we pick apart Boeing, we have not done the same to the pilots.

At the time of the crash, it appears that the established procedures were insufficient. In particular, the MCAS failure creates a qualitatively different 'runaway stabilizer' than the previously-imagined failure mode of a stuck-on motor.

In turn, that seems to have created a situation where the pilots did accurately follow the runaway stabilizer checklist, but the trim was so far off neutral that they could not manually control it.

That's why the article here notes that the older-spec second switch, which deactivated just autopilot inputs into the electric trim system, could have helped. However, that is still far from a final answer, since the troubleshooting checklist would still need modification to try deactivating just auto-trim rather than both switches.

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

#23

Post by sokoloff »

CamperBob2 wrote: post #16
dd36 wrote: post #6

Earlier quoted context omitted.

Gotta love deregulation. How many institutions are left? Any? CFPB, EPA, HUD, Interior are all run by people that don’t believe in their missions. It’s all about undermining from inside. Who protects the public when private rights of collective action are forbidden by arbitration agreements and the government has been captured by private interests?

Gotta love deregulation. Remind me, when's the last time we had a major fatality incident in the US domestic passenger airline business? And how does that compare with the prevailing state of affairs before "deregulation?" Difficulty: answer with numbers, please, rather than insults, downvotes, or political attacks.

Colgan Air 2407 was in 2009. Comair 5191 was 2006. Both, like most airplane crashes, were substantially pilot error. (Both of these were primarily pilot error.)

Weather forecasting has gotten much better in the years since deregulation. We’ve also been operating a mostly-jet fleet, which has larger inherent performance margins than the turboprops (and, worse, pistons) before them. And we have decades of experience about how pilots kill airplanes to inform operations and regulations.

It’s not clear that airfare deregulation either hurt nor helped airline safety in the US. US-flag air carrier ops are extraordinarily safe and I believe the FAA makes a positive contribution to that outcome.

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

#24

Post by bumby »

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…

I think their safety system analysis made the connection MCAS is potentially hazardous as previously reported by the Seattle Times

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

#25

Post by acidburnNSA »

dd36 wrote: post #6
MaxBarraclough wrote: post #4

Earlier quoted context omitted.

One of the lessons learned is that the FAA is no longer a credible institution.

Gotta love deregulation. How many institutions are left? Any? CFPB, EPA, HUD, Interior are all run by people that don’t believe in their missions. It’s all about undermining from inside. Who protects the public when private rights of collective action are forbidden by arbitration agreements and the government has been captured by private interests?

The Nuclear Regulatory Commission is doing just fine in their function.

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

#26

Post by bumby »

eigenvector wrote: post #9
exabrial wrote: post #7

> As various warnings went off in the cockpit, they never reached the conclusion to use the runaway stabilizer procedure. We continue to put the microscope on Boeing but this is why there is a person in the cockpit: to oversee the planes automated systems. There were multiple failures, and while we pick apart Boeing, we have not done the same to the pilots.

If a hazard or potential failure mode can be eliminated in the design of a system, it's better to do that than to rely on every single operator to mitigate it individually.

Exactly. Engineering the hazard out of the system is a vastly superior way of mitigating it than relying on administrative/operational procedures for mitigation

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

#27

Post by techslave »

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.

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

#28

Post by djsumdog »

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 predictable maneuvering. Yes, pilots would have to be certified for these new plans, but that cost pails to the money lost from these grounded fleets.

I'd honestly like to see the 737 MAX taken out of service and Boeing simply ending this line. The old planes should be stripped for parts and as much recycled as possible. It's going to cost them a lot of money, and it should. Their mistakes lead to the deaths of two whole planeloads of passengers. Airbus, Bombardier and others will probably make a lot out of this disaster, and that's probably a good thing and will help competition in this small/narrow market.

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

#29

Post by bumby »

rootusrootus wrote: post #21
ricardobeat wrote: post #13

Earlier quoted context omitted.

Read up on the extensive reporting on both accidents. They never reached that conclusion because it was absolutely unexpected, as a result of Boeing’s stealth changes to the aircraft. There was an article recently where they put very experienced pilots in a simulator under the same conditions and they all failed.

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.

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

#30

Post by djsumdog »

acidburnNSA wrote: post #25
dd36 wrote: post #6

Earlier quoted context omitted.

Gotta love deregulation. How many institutions are left? Any? CFPB, EPA, HUD, Interior are all run by people that don’t believe in their missions. It’s all about undermining from inside. Who protects the public when private rights of collective action are forbidden by arbitration agreements and the government has been captured by private interests?

The Nuclear Regulatory Commission is doing just fine in their function.

True, but I also doubt we'll see new nuclear facilities in the US any time soon.
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