Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

nytimes.com

Post reply on HN
Print view View original

81–90 of 280 posts

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#81

Post by CydeWeys »

Causality1 wrote: post #57
ficklepickle wrote: post #52

This whole plane sounds like any ugly hack. They slapped very different engines on an existing airframe. Then, when it inevitability exhibited undesirable behaviour, they tried to paper over the cracks. Then they hid this information from their customers, regulatory agencies and the pilots. It makes me wonder if there are other issues with the Max that the public doesn't know about yet. I hope a thorough review of Bo…

Indeed. The article makes it sound like a foul-up late in the design process, but this plane was corrupt from the very beginning when Boeing set out to dodge the requirement for re-certifying the airframe.

The FAA needs to grow a pair and declare this type certification and all other certifications older than ~30 years EOLed. That doesn't mean you can't continue operating those planes, it just means you can't retrofit some changes onto a deeply legacy model and still call it the same type.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#82

Post by CydeWeys »

cameldrv wrote: post #51
phkahler wrote: post #42

Earlier quoted context omitted.

But MCAS was added because the plane doesn't handle well in some situations.

I haven't heard of it ever activating except in the incident/accident flights. It's required for certification, but you would either have to be mishandling the plane or get in some extreme weather for MCAS to activate. Think about it like the Antilock brakes on your car. Suppose the wheel position sensor fails. It's fine if the car puts up a warning light and says that you don't have antilock brakes anymore. You can…

ABS isn't the best example because it does prevent lots of accidents in its own right, including a >50% prevention rate of some types of accidents in rainy, snowy, or icy weather. The overall fatal accident reduction is 15% for cars and 27% for trucks and light trucks. Source: https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/...

And, anecdotally, I've had ABS kick in in some occurrences for which I was very thankful.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#83

Post by mgsouth »

2Ccltvcm wrote: post #68
mnw21cam wrote: post #67

Earlier quoted context omitted.

If all you are using is ground-based position/speed, then you are ignoring the very real possibility that the air you are flying through is not stationary relative to the ground. In actual fact, especially at high altitudes, the air can be moving very fast, and the difference between ground speed and airspeed can be the difference between flying and stalling. Also, your GPS measurements give you position, direction,…

Can a near-stall condition be detected solely with some combination of GPS, accelerometer, and barometer?

[Disclaimer: not an aeronautical enginner or pilot.]

Unfortunately, no. Stalling is a function of the wing's _angle_ relative to the flow of air, not of speed. If the angle is too sharp the air can't follow the curve of the wing. The critical angle is (pretty much) independent of speed. For example: if you stick your hand out of the window of a car traveling at 60 MPH, and hold it almost flat to the wind (say 80 deg.), then the air can't follow down the back of your hand. All of the "push" is backwards, and there's no push up. If you hold it at 30 deg. then the air flows around your hand, which deflects the air down and your hand up, very strongly.

Even if you're only traveling at 5 MPH, if you hold your hand at 30 deg. the air will flow around your hand and deflect it upward; it will just be a very weak effect.

The angle between the wing and the air flow is what is called the "angle of attack", and what the AoA sensors measure. The only other instrument that comes close is the Attitude gauge (the globe thing). However, it measures the plane's angle relative to the horizon, and air moving relative to the plane usually isn't parallel to the ground in conditions where the AoA matters.

Wikipedia article, with much detail, pictures, etc.: https://en.m.wikipedia.org/wiki/Angle_of_attack

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#84

Post by basicplus2 »

CydeWeys wrote: post #81
Causality1 wrote: post #57

Earlier quoted context omitted.

Indeed. The article makes it sound like a foul-up late in the design process, but this plane was corrupt from the very beginning when Boeing set out to dodge the requirement for re-certifying the airframe.

The FAA needs to grow a pair and declare this type certification and all other certifications older than ~30 years EOLed. That doesn't mean you can't continue operating those planes, it just means you can't retrofit some changes onto a deeply legacy model and still call it the same type.

I think its not about retrofitting and more about retrofitting (engines in this case) in the wrong place.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#85

Post by danols »

The day someone very high up the corporate ladder truly gets held responsible for this type of greed & negligence and will be put a way for a long prison sentence would be a good day for society. But I am not holding my breath...

But I hope that the CEO Dennis Muilenburg deep down understands he seriously fuxxed up real bad and every now and then is having a hard time falling a sleep in his $10M mansion knowing that he is ultimately responsible for hundreds of peoples unnecessary deaths due to his failed values as a leader.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#86

Post by basicplus2 »

All this talk about how mcas was not designed properly or how it could be prevented from failing is eroneous.

Good safe airplane design is about a neutral flying design without the need for complex systems.

This plane is fundamentally flawed because the engines are in the wrong position because the landing gear is two short to fit them in the correct position.

The test pilot was clear about very poor flying characteristics at slow flyong speeds requiring mcas to be more aggressive.

This plane should not be flying with this engine configuration as it fails the most fundamental principal of good aeroplane design of neutral handling.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#87

Post by tacosx »

CamperBob2 wrote: post #48
oldjokes wrote: post #44

Earlier quoted context omitted.

Anything short of admitting "we fundamentally screwed up, and are rethinking the poor decision to pair this engine with this airframe" as well as "we are reviewing all our design processes and how the FAA oversees every step of the process" is unacceptable. MCAS is just the horrific bloody bandage that is peeling away, it's not actually the problem here. This probably won't happen of course, all they seem to want to…

Anything short of admitting "we fundamentally screwed up, and are rethinking the poor decision to pair this engine with this airframe" Can you cite the basis for this often-expressed sentiment? There's absolutely no reason why a properly-designed and -vetted MCAS system wouldn't have been a perfectly acceptable solution to any handling irregularities caused by the engine configuration. The idea was fine. The fault wa…

It's not impossible to make it work, and in the future I'd expect more and more automated systems in planes for sure.

But you have to recognize the whole engine hack is just a convoluted workaround to avoid as much pilot training as possible. The entire goal of the project seems to be to avoid ever training pilots for as long as possible. It's a brand new plane, the newest plane on the market, and the first thing you need to do to take off is turn off the cabin air conditioning. Why? Because that's what we had to do 50 years ago in the first 737.

God forbid this plane startup any way besides turning off the cabin air conditioning. If we changed that, we'd have to... gasp retrain pilots!

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#88

Post by sk5t »

djsumdog wrote: post #76
ficklepickle wrote: post #52

This whole plane sounds like any ugly hack. They slapped very different engines on an existing airframe. Then, when it inevitability exhibited undesirable behaviour, they tried to paper over the cracks. Then they hid this information from their customers, regulatory agencies and the pilots. It makes me wonder if there are other issues with the Max that the public doesn't know about yet. I hope a thorough review of Bo…

The sad thing is that we'll probably see this plane fly again by the end of the year, because the millions of dollars in retrofits will still be cheaper than having to scrap all existing planes. We have no idea what other potentially lethal corners have been cut. What if they go back into service, after several months of retrofitting all of them at Boeing maintenance hangers, and then the following year there are two…

In what world is scrapping the airframes due to a (serious) software fault the best and most sensible solution? Do you believe there could be undiagnosed problems with the wings, fuselage, tail, hydraulics, electrics, fueling system, gear, etc.?

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#89

Post by inferiorhuman »

sk5t wrote: post #88
djsumdog wrote: post #76

Earlier quoted context omitted.

The sad thing is that we'll probably see this plane fly again by the end of the year, because the millions of dollars in retrofits will still be cheaper than having to scrap all existing planes. We have no idea what other potentially lethal corners have been cut. What if they go back into service, after several months of retrofitting all of them at Boeing maintenance hangers, and then the following year there are two…

In what world is scrapping the airframes due to a (serious) software fault the best and most sensible solution? Do you believe there could be undiagnosed problems with the wings, fuselage, tail, hydraulics, electrics, fueling system, gear, etc.?

In what world is scrapping the airframes due to a (serious) software fault the best and most sensible solution?

A world in which the faulty software was required to fix faulty hardware.

Re: Boeing Built Deadly Assumptions into 737 Max, Blind to a Late Design Change

#90

Post by inferiorhuman »

K0balt wrote: post #65
Causality1 wrote: post #57

Earlier quoted context omitted.

Indeed. The article makes it sound like a foul-up late in the design process, but this plane was corrupt from the very beginning when Boeing set out to dodge the requirement for re-certifying the airframe.

To be fair, it's not like this isn't standard industry practice. Airframe evolve and change, with incremental changes typically only affecting limited areas of impact. OTOH seeking a non aerodynamic solution to a significant stability degrading airframe modification was IMHO a bridge too far. If the pitch stability (not the pitch feel) problems couldn't be dealt with aerodymancally without busting type certification,…

If you make the plane wider you run into issues finding room for it at the gates.
Post reply on HN