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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

#101

Post by hirowan »

skybrian wrote: post #97
owenversteeg wrote: post #90

Earlier quoted context omitted.

>(Not to mention that these planes have never crashed in most countries, even with an admittedly serious bug.) In... Most countries? That's such a weird standard to hold an aircraft to. Even very serious aircraft issues before typically only resulted in crashes in a handful of countries! Did I read that wrong or do you want 100+ of the 200ish countries in the world to have experienced a 737 MAX crash before scrapping…

Just putting the safety record into context. Actually, I think if the planes can be fixed (and I'd be shocked if they couldn't), the two crashes before the fix will no longer be relevant for assessing safety.

You're putting the safety record into chauvinist context, to be exact. An AoA failure is sufficiently rare for it to have only occured in a couple of occasions in - shockingly - only a couple of countries.

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

#102

Post by CydeWeys »

joe_the_user wrote: post #64
erentz wrote: post #43

Earlier quoted context omitted.

> 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…

I'm not an engineer but what about: A) Adding two more angle-of-attack sensors so a pilot can be reasonably sure of auto-adjust will work. Retrofitting those would be expensive, of course. B) Put the two buttons back the way they were and add a "light" indicator an angle-of-attack sensor failure. C) More pilot simulator training so pilots know what to expect in the unusual situation that the system fails. I suspect t…

You need three redundant sensors for safety-critical systems, so that if one fails you know which one is failing. Airbus has three AoA sensors (and three of others as well) on their planes for this reason.

And it's worth pointing out that 737s already have two of these sensors, but don't use them both for MCAS (?!?!).

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

#103

Post by hirowan »

skellera wrote: post #81
nikofeyn wrote: post #52

Earlier quoted context omitted.

it’s not just pr reasons. they tried to hot patch this airplane design with software, and now they are hot patching that fix. it seems it is a fundamentally flawed design that they tried to hide and get away with rather than doing the right thing. i know i don’t want to fly on a 737 max ever, and this whole ordeal with boeing and the faa has made me less confident in the airline industry as a whole. your parenthetica…

Pilots are highly trained. They go through many hours of simulated flights. After an incident like this, any pilots still flying a MAX will be drilled on this specific failure. If you start to see pilots refuse to fly it, that’s when you should worry. Aviation adapts to problems and it always has. Southwest installed additional gear on their planes to help prevent this when the first plane crashed. It’s not far fetch…

> After an incident like this ...

Clearly, that didn't happen, or a second MAX wouldn't have crashed under very similar circumstances.

> Southwest installed additional gear on their planes to help prevent this when the first plane crashed.

Southwest ordered the MAX with an AoA indicator; it wasn't retrofitted.

> ... to help prevent this ...

It's questionable whether the AoA indicator would've made a difference. However, an AoA disagree alert that is standard in the previous 737 gen was "accidentally" made part of the AoA indicator extra feature set on the MAX, and the AoA disagree just _might_ have made a difference. [1]

> It’s not far fetched that companies in countries with lesser regulations might skip out on training or plane enhancements that would lessen the chances of this problem.

An AoA indicator is not mandatory anywhere in the world.

[1] https://www.aviationtoday.com/2019/05/06/boeing-angle-of-att...

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

#104

Post by skybrian »

hirowan wrote: post #101
skybrian wrote: post #97

Earlier quoted context omitted.

Just putting the safety record into context. Actually, I think if the planes can be fixed (and I'd be shocked if they couldn't), the two crashes before the fix will no longer be relevant for assessing safety.

You're putting the safety record into chauvinist context, to be exact. An AoA failure is sufficiently rare for it to have only occured in a couple of occasions in - shockingly - only a couple of countries.

Okay, I probably should have calculated the number of successful flights to avoid this. But, nowhere did I say any country is better than any other. That's your inference.

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

#105

Post by EdwardDiego »

jhayward wrote: post #87
old-gregg wrote: post #65

Earlier quoted context omitted.

> The bugs will be addressed and they'll still fly. The engines are mounted incorrectly, so much so that Boeing believed pilots need the assistance of MCAS on take-off now. The bug isn't with its algorithms, rather the need for MCAS to begin with. They can't "address" it. That's why I'll be very careful not to ever book a flight on a 737 Max, probably easier to simply stick to Airbus-only airlines: Jetblue, Alaska/Vi…

> The engines are mounted incorrectly, so much so that Boeing believed pilots need the assistance of MCAS on take-off now. This overstates the issue. The engine mounting changes the flight characteristics enough that the MAX 8 needs to be flown differently in certain corners of the flight envelope. The MCAS was added to avoid having to re-train pilots or trigger a new type certification. The engine mounting certainly…

Why is this commenter grey in my thread? They are absolutely correct, and anyone who disagrees really needs to say why.

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

#106

Post by CydeWeys »

skybrian wrote: post #97
owenversteeg wrote: post #90

Earlier quoted context omitted.

>(Not to mention that these planes have never crashed in most countries, even with an admittedly serious bug.) In... Most countries? That's such a weird standard to hold an aircraft to. Even very serious aircraft issues before typically only resulted in crashes in a handful of countries! Did I read that wrong or do you want 100+ of the 200ish countries in the world to have experienced a 737 MAX crash before scrapping…

Just putting the safety record into context. Actually, I think if the planes can be fixed (and I'd be shocked if they couldn't), the two crashes before the fix will no longer be relevant for assessing safety.

This isn't a valid way to put it into context. It doesn't matter which countries the planes crashed in; the causes were the same and lives lost are lives lost. And air travel is so globalized these days that one crash anywhere can kill citizens of dozens of countries.

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

#107

Post by davidkuhta »

an_account_name wrote: post #93
djsumdog wrote: post #30

Earlier quoted context omitted.

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

Some of these applications have been withdrawn, but there are in fact some in flight. https://www.nrc.gov/reactors/new-reactors/col/new-reactor-ma...

> In flight

Hopefully, their planes don't need MCAS ;)

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

#108

Post by zb »

rootusrootus wrote: post #19
AnthonBerg wrote: post #10

Earlier quoted context omitted.

The core of the discussion precisely revolves around Boeing wilfully making it more difficult for the person in the cockpit to oversee the planes' automated systems.

It would not be invalid to observe that the first Lion Air crew dealt successfully with the malfunction, and ask why the second crew did not. Every aspect of these accidents should be investigated.

If I recall correctly, the first crew encountered the issue during cruise, at which point which you have both (a) time, and (b) sufficient altitude that you can afford to push the stick forward in order to reduce the aerodynamic force on the horizontal stabiliser to the point where it will be physically possible to correct the trim without powered assistance.

Pilots encountering the issue during takeoff have neither of those things, with results that we've already observed.

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

#109

Post by CydeWeys »

cm2187 wrote: post #95
blattimwind wrote: post #56

Earlier quoted context omitted.

> 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. A brand new design actually supporting the engines used would not have aerodynamic issues that place the airframe outside the limits set forth by regulations.

I think the point if the OP isn't that a new design would have the same flaw, but rather that it would possibly introduce many other flaws. I think the analogy to a full software rewrite vs fixing a bug in a battle tested software is relevant.

The larger point is that the 737 is a highly antiquated design by this point. The cockpit has screens that emulate old analog displays to maintain common type rating, even though much better ways of displaying that data now exist. The plane's controls are highly manual, which are a negative now that fly-by-wire and autopilots are mature and very good. Hell, the entire plane sits so low to the ground because it was designed to support a non-jetway use case (which is now non-existent), and as a result 737s are more susceptible to foreign object damage from debris sucked up off the runway.

The 737 is riddled through with legacy design features and needs to be put to pasture once and for all. And designing a replacement wouldn't be from scratch; there are plenty of other modern airliners to base a new one off of.

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

#110

Post by CydeWeys »

guelo wrote: post #78
dsfyu404ed wrote: post #51

Earlier quoted context omitted.

EPA has been a joke for at least two, I want to say three, administrations now. Now they're just a joke that doesn't impede business quite so much.

Explain. What about it has made it a joke?

Its head, Andrew Wheeler, is a former coal lawyer. That tells you all you need to know.

Bit separately, I know people in DC who work in this field and they say the same thing.

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