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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

#211

Post by manigandham »

michaelmrose wrote: post #206
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…

Citation needed

Ok, start with Boeings page: http://www.boeing.com/commercial/737max/737-max-software-upd...

And here's a good overview: https://leehamnews.com/2018/11/14/boeings-automatic-trim-for...

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

#212

Post by michaelmrose »

TomVDB wrote: post #168
bushido wrote: post #112

Earlier quoted context omitted.

It seems like this is becoming a concern now - per: https://www.cnbc.com/2019/05/07/barclays-downgrades-boeing-s... The primary reason for the downgrade being: Barclays’ survey of airline passengers says many people will avoid the 737 Max “for an extended period” once the aircraft is flying again.

Here’s my thought experiment on that: if I booked a flight to my vacation destination and, at the last moment, I discovered that I’d be flying in a 737 MAX, would I cancel my trip or pay a considerable amount of moment to get all our tickets changed? I very likely would not. Would you? Would others? It’s one thing to answer a question of a pollster, it’s another to take concrete action.

You typically can see the type of plane on travel sites. If this wasn't the case I would buy from one that did.

In the case that I for some reason couldnt determine it ahead of time I would complain emphatically enough.

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

#213

Post by raverbashing »

kortilla wrote: post #181
CydeWeys wrote: post #109

Earlier quoted context omitted.

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 de…

>so low to the ground because it was designed to support a non-jetway use case (which is now non-existent) Complete bullshit. I’ve boarded/deplaned without a jetway in Beijing, SLC, JAC, and AMS in the last couple of years alone.

It's not a "non-jetway" case, it's a non jetway and no airport stairs case and/or manual loading of cargo

An embedded staircase is an option on the 737

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

#214

Post by manigandham »

basicplus2 wrote: post #142
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…

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.

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

#215

Post by silvestrov »

madarcho wrote: post #207
__m wrote: post #202

Earlier quoted context omitted.

Wouldn’t they eventually all freeze at roughly the same position when the AoA doesn’t change for a while? Can’t they be heated?

They definitely are now. If you want to see what they look like, the channel AvE on YouTube tears one down (Search for BOLTR AoA) and discusses the mechanics. You can see what they suspect to be small cables for heating go up into the element.

https://www.youtube.com/watch?v=NhZ0D-JRtz0

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

#216

Post by theclaw »

davewasthere wrote: post #66
massysett wrote: post #46

Earlier quoted context omitted.

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

Yeah, but who is going to want to fly in one again? Even working in aviation in the past and knowing that they've probably nailed the issue, I'd still be less than keen.

Boeing could simply rebrand the plane. Take ‘MAX’ out of the name, call it a 737-8. I think most people have absolutely no idea what model of plane they’re flying on anyway.

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

#217

Post by michaelmrose »

Aeolun wrote: post #169
cjbprime wrote: post #156

Earlier quoted context omitted.

I can help with that -- the MAX is suffering hull losses per flight completed at a rate about 100x that of comparable planes like the A320. Totally off the charts.

It’s such a weird statistic to use though. One crash takes a really long time to recover from in that score. So even if the 737 Max was magically fixed tomorrow, the score wouldn’t change.

It's not remotely a strange choice when it represents the current most reasonable prediction of risk.

If it were fixed tomorrow at that point we could discuss how it effects risk in the future.

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

#218

Post by bronson »

manigandham wrote: post #204
JudgeWapner wrote: post #111

Earlier quoted context omitted.

> The engine mounting certainly does not make the plane unsafe. I don't think this is a very...'precise' statement. what is "safe" in the context of aviation? If you had no MCAS, then this plane has a very bad propensity to stall . I hope we can both agree that's an unsafe airplane. You can't just say "don't do that [pull up too much] and then you're fine". The aircraft "wants" to pitch up too high and stall, which p…

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 profile (including high AOA), it's demonstrably wrong to say "the aircraft flies fine." Maybe it will eventually "fly fine" but Boeing's got quite a bit of work to do first.

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

#219

Post by bushido »

TomVDB wrote: post #168
bushido wrote: post #112

Earlier quoted context omitted.

It seems like this is becoming a concern now - per: https://www.cnbc.com/2019/05/07/barclays-downgrades-boeing-s... The primary reason for the downgrade being: Barclays’ survey of airline passengers says many people will avoid the 737 Max “for an extended period” once the aircraft is flying again.

Here’s my thought experiment on that: if I booked a flight to my vacation destination and, at the last moment, I discovered that I’d be flying in a 737 MAX, would I cancel my trip or pay a considerable amount of moment to get all our tickets changed? I very likely would not. Would you? Would others? It’s one thing to answer a question of a pollster, it’s another to take concrete action.

As others have stated, I will not be booking a ticket on a 737 max, period.

Granted I might not be a typical discount shopper, I pick flights based on comfort, not price and have checked the aircraft/airframe I will be in for years.

However, I have a tough time seeing anyone I know taking a risk with flying the 737 max for a 10% discount in fares.

Typically, fuel costs to the airline can be estimated at 10-20% of the ticket price on domestic flights (5 gallons per seat per hour). 737 Max is advertised as providing up to 20% in fuel cost saving, which would bring the cost to 4 gallons per seat per hour. Which should not affect a ticket price by more than $4-6 per hour of flight.

Are you suggesting that people aware of the issue will be wiling to risk their lives for a chance to save $8-20 to their destination?

And to add to that very few 737 Max are in service right now, only 300 or so of 5000 orders have been fulfilled. These supposed savings are not yet factored into the price of most tickets, they are future reductions at best. And likely these will not even be reductions, just a way for carriers to earn more per seat.

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

#220

Post by lagadu »

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.

Well, yes: the plane is inherently unstable. That's why the MCAS system is there. The system itself is mostly fine, it does what it's intended to under ordinary conditions. The problem was that Boeing, in order to avoid costs to the buyer, declared that pilots did not require training on it and made the instrumentation that manages the system woefully inadequate to the task of handling malfunctions (plus the system relying on a single sensor is pretty brittle but adequate malfunction handling instruments would've mitigated that).
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