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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

#281

Post by bronson »

Dylan16807 wrote: post #230
rocqua wrote: post #227

Earlier quoted context omitted.

Not quite if I am to believe other HN comments. The thing MCAS compensates for is that, in certain cases, as you pitch up more, the pressure on the stick decreases. This feels to pilots like leveling out, which is dangerous. MCAS was designed to counter this. The specific design of MCAS and not adding any new procedures, was to lower the training requirements. Specifically, anyone certified on the old 737 was still c…

> This feels to pilots like leveling out, which is dangerous. MCAS was designed to counter this. Pilots are trained extensively not to trust what motion feels like, and to use the horizon and instruments. An adjustment in stick pressure is not a notable new threat, they just need to be trained for the plane's behavior.

That’s the whole point: the MCAS was supposed to be cheaper/easier for the airlines than new training.

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

#282

Post by foldr »

michaelmrose wrote: post #205
kuzehanka wrote: post #182

Earlier quoted context omitted.

So much ignorance and misinformation about this issue even on HN. The parent comment and entire thread is 100% correct. There is nothing inherently unstable or unsafe about the MAX 8. It has a pitch-up characteristic that's mild compared to some other commercial jets like the 757. The only reason MCAS was put on that plane was to allow the MAX 8 to share a type rating with the rest of the 737 family, to make it so th…

Nobody who isn't an engineer wants is terribly interested in the argument that a model of plane that has killed 2 planes full of people recently is in anyone's opinion safe. Personally I won't fly on one in my lifetime. I'll leave the analysis of why to others to figure out why I fly on other airplanes. Incidentally I have seen pilots argue that the max is inherently unsafe on this forum which is probably why people…

You're missing the point of the post you're responding to. The poster is saying that the 737 MAX isn't inherently unsafe due to its aerodynamic configuration. The safety issue arose from the bungled MCAS system. This could be fixed without changing the airframe.

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

#283

Post by staunch »

smadurange wrote: post #192
staunch wrote: post #68

Earlier quoted context omitted.

What regulations are you referring to? Yes, it's true that it would be have been free from this specific MCAS issue. But what other issues would a new design have had? It's impossible to know. It's also true that if Boeing had done a better job of implementing the MCAS design it would have been viewed as a triumph of software solving hardware problems. Air France 447 crashed in large part because the pilot flying was…

Airbus uses software to enhance safety. MCAS is trying to fix a very specific and a potentially dangerous issue while keeping it from the pilots. So, I'm not sure if there's a good analogy there.

In both cases the software was designed to prevent the pilot from stalling the aircraft i.e. to enhance safety.

And yet hundreds of people died in Air France 447 because the pilot stalled the aircraft when sensor failure disabled the Airbus software without the pilot realizing it.

In the case of MCAS, people died because the Boeing software didn't disable itself due to sensor failure.

Definitely not the same issue but both examples of software-sensor-related fatal crashes.

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

#284

Post by bumby »

simion314 wrote: post #201
manigandham wrote: post #80

Earlier quoted context omitted.

There's no fundamental design flaw, the aircraft is sound. The problem came from using software systems to artificially make the plane behave like older designs to avoid entirely new training and certifications. Even that would've been acceptable and similar systems are already in use in other planes but it was the inadequate info, redundancy, warnings and controls to disable the system that created the problem. It's…

>There's no fundamental design flaw, the aircraft is sound. You can claim this because now all the FAA approvals for this planes, all tests need to be redone by somebody that we can trust. Sure they but larger engines, did they improved the supports, the bolts ,FAA "checked" this updates but can you trust them? the idea that MCAS is the only subsystem that must be fixed and checked is flawed, everything needs to be t…

Part of the problem is that Boeing changed the trim increment AFTER the FAA certification without FAA knowledge. I'm surprised a configuration change like that was allowed and wonder what level they were analyzed by safety engineers.

So there's not just the design workaround but there seems to also be process gaps that contributed to the situation.

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

#285

Post by mveety »

bronson wrote: post #281
Dylan16807 wrote: post #230

Earlier quoted context omitted.

> This feels to pilots like leveling out, which is dangerous. MCAS was designed to counter this. Pilots are trained extensively not to trust what motion feels like, and to use the horizon and instruments. An adjustment in stick pressure is not a notable new threat, they just need to be trained for the plane's behavior.

That’s the whole point: the MCAS was supposed to be cheaper/easier for the airlines than new training.

You wouldn’t be retrained to ignore cues from your senses and trust your instruments. That training happens when you’re young and getting your IFR ticket.

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

#286

Post by blattimwind »

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.

> Remind me, when's the last time we had a major fatality incident in the US domestic passenger airline business?

Doesn't really matter much. Incidents in aviation that can happen on continent X could usually have happened on any continent.

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

#287

Post by davidf18 »

kuzehanka wrote: post #182
kortilla wrote: post #138

Earlier quoted context omitted.

No, it did not “have a bad propensity to stall”. That’s a very imprecise statement in the first place but if you take it to mean, it would try to stall during normal flight conditions, it’s definitely false. Airbus aircraft are “safe” despite the fact that dual conflicting pilot input is averaged without stick feedback (see the Airfrance flight from Brazil). If electronics being used to fly the aircraft upsets you, y…

So much ignorance and misinformation about this issue even on HN. The parent comment and entire thread is 100% correct. There is nothing inherently unstable or unsafe about the MAX 8. It has a pitch-up characteristic that's mild compared to some other commercial jets like the 757. The only reason MCAS was put on that plane was to allow the MAX 8 to share a type rating with the rest of the 737 family, to make it so th…

The 737-MAX with the larger engines turned the statically stable airframe into one that must use computers (eg MCAS) to make it dynamically stable which is a technique used on modern fighter jets but to my knowledge has never been applied to a passenger aircraft.

In this plane which is not "fly-by-wire" the pilots are part of the safety loop and are given a certain short amount of time to respond to an emergency.

Troubling to me is the footnote in the manual which there are times where the manual wheels for the trim require 80 lbs or 100 lbs or more of force. This amount of force would potentially preclude female pilots on these planes to handle these sorts of emergencies.

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

#288

Post by jwr »

the_mitsuhiko wrote: post #253
nicoburns wrote: post #248

Earlier quoted context omitted.

Why not?

Because it has grandfathered rules that new planes don’t have it depends on. For instance no new plane design us allowed to have 737 style emergency exits.

Oh, that's bad. In that case, I expect we will see it forced through the regulatory pipeline, because Boeing is "too big to fail". This is not good, neither for us passengers nor for aviation safety in general.

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

#289

Post by jeanl »

user5994461 wrote: post #262
eCa wrote: post #243

Earlier quoted context omitted.

> Airlines have no choice Anecdotal: I know of at least one family that booked a trip on a non-Boeing airline, at additional cost, to avoid risking being on a Max. Imagine that after the Max is back in service, that there is a serious incident in the first few months - it doesn't have to be fatal, just a close call of some kind - how many more customers will avoid the Max at all costs?

How do you know the plane model before you board? It's not shown when buying the ticket, it's not written on the ticket either.

You can find that at https://flightaware.com just from the flight number...

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

#290

Post by ricardobeat »

rootusrootus wrote: post #79
addicted wrote: post #69

Earlier quoted context omitted.

It’s like seeing someone make a half court shot in basketball at the buzzer and wondering why other players don’t do the same. You could adjust the probability to it being a 3 pt shot, dunk, or free throw. The failures in the Boeing 737 introduced a significant probability of unrecoverable failure. The fact that a few pilots managed to recover does not mean that the ones who didn’t recover did something wrong. On the…

Sorry to confuse, I am not really interested in assigning blame. I am more interested to see what can be learned from this so flying continues to get safer. That will include looking at how the pilots responded to the training material in practice, and figuring out how that plays into designing future procedures, documentation, and training. I get that nobody here seems to have much appreciation for human factors, bu…

The entire discussion does revolve around human factors; how decisions were made, how the changes were designed to avoid the need for retraining, and in this specific article, designed to hide a change under the guise of preserving standard procedures for the people flying the plane. I’m not sure what other angle you’re after.
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