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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

#301

Post by hakfoo »

avar wrote: post #223
cletus wrote: post #118

So a lot is known at this point: 1. The A320neo caught Boeing completely off-guard; 2. The threat of the likes of American Airlines (already a mixed Airbus/Boeing customer and the largest airline in the world) placing a large A320neo order for regional aircraft operations scared the bejesus out of Boeing management; 3. For airlines like Southwest that are pure 737, the prospect of adding a plane that didn't share a c…

> the plane CLEARLY flies differently to a 737[...] There's no such thing as "a 737". A 737-600 is 31 meters long[1], and a 737-900ER is 42 meters. Both share the same type rating with the MAX[2], and have the same 36 meter wingspan. That's going from a length:span ratio of 0.86:1 to 1.17:1, you think those sort of airframe changes don't make for a plane that flies differently? Maybe the whole notion of a "common typ…

I think it's all about how far off the mean you are.

Consider cars: You can get most full-size sedans with either four or six cyliner engines, manual or automatic transmission, and regular or sporty suspensions. That's potentially eight different sets of handling characteristics. But they're all going to be in a fairly narrow cluster of "this still drives pretty much like a Camry." When you decide "instead of the six-cyliner engine, let's drop in a 700 horsepower turbocharged V8", it's no longer anywhere near that cluster.

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

#302

Post by subway »

anticensor wrote: post #292
echelon wrote: post #273

Earlier quoted context omitted.

I'm not going to fly on any 737, just in case the MAX bit gets truncated. Everyone I've talked to has expressed the same fear. I don't care if it's irrational or not - it's my life, and I'm not risking it on one of these stupid, cost-cutting planes.

Boeing 737-MAX is longer than previous iterations of 737.

And that means...?

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

#303

Post by CamperBob2 »

blattimwind wrote: post #286
CamperBob2 wrote: post #16

Earlier quoted context omitted.

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.

A good counterexample: in the Lion Air case, at least one planeload of passengers came within a hair's-breadth of disaster prior to the fatal crash. The pilots figured out what to do in time, in part because a third pilot was available to RTFM while the other two flew the airplane. However, that crew not only didn't take any action to remove the aircraft from service, they apparently didn't even bother to leave a Post-It note on the dashboard.

The regulations we have in place here in the US -- to say nothing of our airlines' own policies -- would have kept that aircraft grounded until the problem was diagnosed and addressed.

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

#304

Post by anticensor »

subway wrote: post #302
anticensor wrote: post #292

Earlier quoted context omitted.

Boeing 737-MAX is longer than previous iterations of 737.

And that means...?

You cannot confuse them because of the sheer size and shape difference.

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

#305

Post by thucydidesofusa »

erentz wrote: post #43
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 simp…

Dang, that alternate history fantasy is something the management of Boeing needs to read.

That's so spot on - something like that would have changed the skies. Imagine how many secondary cities could have come online if airlines had cheap 116/141/165 seaters.

I wonder if that would have left too large a gap between the largest C-series and the smallest NMA, you can argue that both would be relentlessly optimized and it'd be really hard for the A320neos to compete on either end.

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

#306

Post by acqq »

manigandham wrote: post #245
codedokode wrote: post #242

Earlier quoted context omitted.

To me MCAS looks like an ugly software hack implemented to save money on redesigning a plane and re-training pilots. It brings several problems: - it is difficult for pilots to understand how MCAS works, and how to diagnose failures. They are not programmers or engineers. And MCAS doesn't provide any debugging information about its work anyway. And pilots don't have time to analyze it. - it adds new points of failure…

Yes, that's what I said. The artificial behavior would be fine if the pilots actually knew it was artificial and how it was being done. That lack of understanding and training is the critical error, made worse by a poorly designed system that failed too easily.

> The artificial behavior would be fine if the pilots actually knew it was artificial and how it was being done.

If I remember correctly, the behavior you promote as "fine" is forbidden by the regulators, and not accidentally.

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

#307

Post by acqq »

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.

> An adjustment in stick pressure is not a notable new threat, they just need to be trained for the plane's behavior.

It seems that what you claim is "not a new threat" is actually forbidden by the regulations, because it was recognized to be a threat.

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

#308

Post by thucydidesofusa »

bronson wrote: post #218
manigandham wrote: post #204

Earlier quoted context omitted.

The aircraft flies fine. MCAS is a stability control system that applies in certain cases (full power, high angle of attack) where the nose pitches up. It may lead to a stall but that's not what it's correcting for and it doesn't just happen during level flight. If the MCAS system was disabled then pilots handle it manually. Trim is not an exotic concept and just takes training and understanding of the operating char…

The aircraft flies fine in most flight profiles, yes. At high angle of attack, the MAX-8 is more unstable than pilots were trained to expect. And the MCAS has done an absolutely miserable job of fixing this. Worst case scenario bad: it caused the loss of two airplanes that, if the MCAS had never been added to the MAX-8, would have reached their destinations just fine. Until the it flies predictably in every flight pr…

The MAX will fly predictably, just perhaps in a way that's ultimately different from the NG 737s, maybe it will mean that pilots will need a check out flight instead of a iPad tutorial. Maybe it means there will be a new type certification, who knows.

All planes with rear engines and t-tails have unforgiving parts to the flight profile, we still fly MD-80s and Boeing 717s and all those regional jets. The Max isn't ideal, but Boeing has a chance of getting ahead of this issue and not junking the product line or existing planes.

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

#309

Post by basicplus2 »

manigandham wrote: post #214
basicplus2 wrote: post #142

Earlier quoted context omitted.

The engines we placed in a far from ideal position because of low ground clearance making the plane not fly close to neutral that is a fundamental design flaw

Normal flight is flight is fine. The issue with the new engines was that the nacelles generated lift in specific scenarios at high-angle-of-attack which changed the pitch. This doesn't mean the aircraft is fundamentally unsound, it's just a flying characteristic and can be managed just fine if the pilots knew about it and what the MCAS system was doing to counter it.

A aeroplane that NEEDS an added control system just to make it APPEAR to fly neutral is a design flaw.

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

#310

Post by manigandham »

acqq wrote: post #306
manigandham wrote: post #245

Earlier quoted context omitted.

Yes, that's what I said. The artificial behavior would be fine if the pilots actually knew it was artificial and how it was being done. That lack of understanding and training is the critical error, made worse by a poorly designed system that failed too easily.

> The artificial behavior would be fine if the pilots actually knew it was artificial and how it was being done. If I remember correctly, the behavior you promote as "fine" is forbidden by the regulators, and not accidentally.

If it’s prohibited then how was it certified?
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