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American Airlines Is Quietly Bringing Back the 737Max

zdnet.com

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Re: American Airlines Is Quietly Bringing Back the 737Max

#101

Post by atharris »

wycy wrote: post #67

I still don't think I'd trust it. While it's probably true that they fixed the software to never again produce this kind of error, I don't like the idea of software being used to correct the fundamental physics that the airframe is dynamically unstable. While the software probably does a good job of correcting it under a wide range of normal operating conditions, can it deal with evolving or abnormal operating condit…

I've said this elsewhere in the thread, but stabilizing a dynamically unstable system is half of the reason why control theory remains an active research area instead of a mathematical backwater; this kind of set up is extremely common for aerospace systems. Software is hard to get right - which is why aerospace software has traditionally faced much higher bars for verification than 'traditional' software (and is much more expensive as a result!) The same is true of hardware, which I think many HN commentators forget; the cost of a bolt or connector that is aerospace-grade is typically many times that of a conventional or automotive-grade part, due mostly to extensive testing+verification required for safety.

Most of the scenarios you're describing are dealt with in a few ways:

1. Building systems with sufficient margin to account for this kind of uncertainty; even with passively stable aircraft, these margins exist. Feedback control typically increases these margins.

2. Extensive verification under a wide range of input conditions; this is more challenging (how can you enumerate every possible failure condition?), but usually boils down to some kind of Monte-Carlo sampling or worst-case analysis when those cases can be identified. Here's [0] a neat paper that does this in a more sample-efficient way.

[0] https://arxiv.org/abs/1709.06645

Re: American Airlines Is Quietly Bringing Back the 737Max

#102

Post by AniseAbyss »

salex89 wrote: post #73
js2 wrote: post #35

Earlier quoted context omitted.

For years after AF447 I was nervous flying airbus. In reality, it's extremely unlikely that you'll die flying. (I'd be nervous flying a Max too, but it's not rational.)

Almost all airline accidents in modern days are "freak" accidents, but I personally consider AF447 one of the freakiest of the freaks. The long wait to figure out what was wrong probably amplifies the feeling.

I'm not an expert but I do watch aircrash investigation and many of the accidents are caused by mistakes from pilots, airtraffic controllers and or mechanics.

Thats why this crash bothers me. A design flaw in a production aircraft is not something you expect in the modern age.

Re: American Airlines Is Quietly Bringing Back the 737Max

#104

Post by tboyd47 »

ajarmst wrote: post #99
tboyd47 wrote: post #78

Earlier quoted context omitted.

Let me remind you of why we're all still talking about Boeing. Not once, but TWICE, software taking readings from faulty sensors caused the airplane to nosedive into the ground, killing every single person on board, with the pilots powerless to take over. It happened once, Boeing and the U.S. government reassured everyone that it wasn't going to happen again, then it happened again. When nations around the world bega…

If your interest is understanding what happened and how it could have been prevented, you would do far better to read the accident reports, in their entirety, carefully. A half dozen cherry-picked and context-free lines from a store of thousands of emails and other documentation are useful for getting clicks and stoking reader emotions to drive social media reposts but are typically less dispositive in failure analys…

I'm not naïve to the depths of depravity the human soul can fall to, nor am I blind to moral subtleties in life.

I'm just a consumer making decisions on behalf of myself and my family, and exercising what little power I have.

"We have a process" is little reassurance when every step of said process failed.

I have a process, too. When I feel safe, I board an airplane. When I don't feel safe, I don't board it and demand a refund from the airline.

Re: American Airlines Is Quietly Bringing Back the 737Max

#105

Post by kirykl »

lbriner wrote: post #52
js2 wrote: post #35

Earlier quoted context omitted.

For years after AF447 I was nervous flying airbus. In reality, it's extremely unlikely that you'll die flying. (I'd be nervous flying a Max too, but it's not rational.)

The difference with AF447 was that the aircraft at no point was defective, it was purely confusion on part of the flight crew and the issue with two pilots "in control" which the Captain absolutely should have dealt with.

The stall warning stopped when the plane was too far into a stall to consider the data valid. I’d say that’s a malfunction for usability. It caused the pilot to keep pulling back because that stopped the warning.

Re: American Airlines Is Quietly Bringing Back the 737Max

#107

Post by dingaling »

js2 wrote: post #77
lbriner wrote: post #52

Earlier quoted context omitted.

The difference with AF447 was that the aircraft at no point was defective, it was purely confusion on part of the flight crew and the issue with two pilots "in control" which the Captain absolutely should have dealt with.

The pitot tubes had iced-over and it wasn't the first time: https://en.wikipedia.org/wiki/Air_France_Flight_447#Pitot_tu... But that's not what made me nervous about Airbus. Rather, that's when I learned that Airbuses are flown by side-sticks that aren't mechanically linked while Boeings are flown by yokes which are. https://en.wikipedia.org/wiki/Air_France_Flight_447#Side-sti... The idea that two pilots can provide…

> while Boeings are flown by yokes which are [mechanically linked]

They can still be disconnected with sufficient opposite force, there's a shearable torque tube between them.

Re: American Airlines Is Quietly Bringing Back the 737Max

#108

Post by iso1631 »

lbriner wrote: post #52
js2 wrote: post #35

Earlier quoted context omitted.

For years after AF447 I was nervous flying airbus. In reality, it's extremely unlikely that you'll die flying. (I'd be nervous flying a Max too, but it's not rational.)

The difference with AF447 was that the aircraft at no point was defective, it was purely confusion on part of the flight crew and the issue with two pilots "in control" which the Captain absolutely should have dealt with.

I won't fly Air France, not just because of AF447, but also the time they diverted into an airport in the middle of a civil war and had a whip round in first class to pay for the gas to get out of there.

https://www.independent.ie/life/travel/travel-news/air-franc...

Re: American Airlines Is Quietly Bringing Back the 737Max

#109

Post by iso1631 »

tboyd47 wrote: post #66
deeblering4 wrote: post #23

I’m at a point where I just opt for carriers with Airbus fleets. I do not trust modern day American corporations nor the oversight bodies. There are too many financial incentives to cut corners.

Yes, same. Too bad we cannot control which airplane we fly on; it's totally up to the airline and they can switch it at any time.

BA are not going to be putting me on a a narrow body Boeing aircraft

Re: American Airlines Is Quietly Bringing Back the 737Max

#110

Post by ajarmst »

tboyd47 wrote: post #104
ajarmst wrote: post #99

Earlier quoted context omitted.

If your interest is understanding what happened and how it could have been prevented, you would do far better to read the accident reports, in their entirety, carefully. A half dozen cherry-picked and context-free lines from a store of thousands of emails and other documentation are useful for getting clicks and stoking reader emotions to drive social media reposts but are typically less dispositive in failure analys…

I'm not naïve to the depths of depravity the human soul can fall to, nor am I blind to moral subtleties in life. I'm just a consumer making decisions on behalf of myself and my family, and exercising what little power I have. "We have a process" is little reassurance when every step of said process failed. I have a process, too. When I feel safe, I board an airplane. When I don't feel safe, I don't board it and deman…

You absolutely have the right to not board an aircraft if you don't feel safe, and should exercise it. Laurence Gonzales has a story about declining to fly on a DC-10, which saved his life. But even he admits that that decision wasn't rational: you can't judge a decision by what you know after the fact. Even at its worst, a flight on a DC-10 was much safer than his morning commute.

You'll have less luck getting a refund for that decision, but I do appreciate your admitting that the decision is about your feelings, not demonstrable evidence.

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