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737 Max: 1960s Design, 1990s Computing Power and Paper Manuals

nytimes.com

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Re: 737 Max: 1960s Design, 1990s Computing Power and Paper Manuals

#71

Post by theclaw »

londons_explore wrote: post #18
pinewurst wrote: post #2

The "1990s Computing Power" comment is ignorantly harsh. The MAX (to the best of my knowledge) uses a similar AMD29050-based architecture as the 777 (where it was pioneered) and the 737-800/900. It's amply fast and very very reliable, hardware and software (setting MCAS aside which is new to MAX). Any sane person would prefer the solid well-proven choice over the bleeding edge. People used to make similar comments ab…

I'm not sure I agree here. There exist possibilities for far more safety with more compute. For example, when a mechanical failure occurs (for example an engine explodes and partially falls off) the flight characteristics of the plane change dramatically. Current systems fall back to human control, and hope that human will be able to figure out how to control a now very "unique" machine. Future systems could dynamica…

There also exists possibilities for far more danger. As you increase compute, you can run more code, and build more complicated interdependent components that are more difficult to test, especially for the sort of unexpected scenarios that "dynamic" behaviour would warrant. You would basically have a whole new plane - the opposite of what the 737 MAX 8 was intended to be.

Re: 737 Max: 1960s Design, 1990s Computing Power and Paper Manuals

#72

Post by JauntyHatAngle »

cm2187 wrote: post #61
JauntyHatAngle wrote: post #56

Earlier quoted context omitted.

>Like, why does such a critical system like MCAS take only a single AoA sensor as input, when there are two sensors available? Specially considering that the inputs from both are hardware-available to MCAS (the new software version is going to take data from both). Are you saying the answer in the article didn't give enough information? "Airbus addressed this potential problem on some of its planes by installing thre…

No it doesn’t answer the question. If there are two sensors already installed, not requiring change, how come the MCAS only uses one, not both?

The article also states that 2 sensors is not enough as then you have two sensors that can disagree with no way to figure out the correct one.

Re: 737 Max: 1960s Design, 1990s Computing Power and Paper Manuals

#73

Post by JauntyHatAngle »

flyinglizard wrote: post #58
kacamak wrote: post #52

Earlier quoted context omitted.

>Like, why does such a critical system like MCAS take only a single AoA sensor as input The classic approach is to have three sensors, so in case one fails you can know which one. Having two only indicates something is wrong but is not useful on the fly.

Three with a disagree algorithm is definitely what I’d expect out of such a critical system, but two with signal averaging would still be much better than just one.

Unless I am misunderstanding what signal averaging is (quite possible) isn't it possible that in situations where the average of a signal is still going to crash the plane, a 50/50 guess is actually more likely to end up with a better chance?

If true, it's possible signal averaging isnt necessarily the best choice

Re: 737 Max: 1960s Design, 1990s Computing Power and Paper Manuals

#74

Post by lqet »

Hm. I hesitate to defend Boeing here, but I think the outset of this article is a bit unfair.

> Pilots start some new Boeing planes by turning a knob and flipping two switches.

> The Boeing 737 Max, the newest passenger jet on the market, works differently. Pilots follow roughly the same seven steps used on the first 737 nearly 52 years ago: Shut off the cabin’s air-conditioning, redirect the air flow, switch on the engine, start the flow of fuel, revert the air flow, turn back on the air conditioning, and turn on a generator.

So? What does this have to do with anything? Is the goal to produce an airplane where pilots press a button "fly to destination", and the plane does it?

> The strategy, to keep updating the plane rather than starting from scratch, offered competitive advantages. Pilots were comfortable flying it, while airlines didn’t have to invest in costly new training for their pilots and mechanics. For Boeing, it was also faster and cheaper to redesign and recertify than starting anew.

> But the strategy has now left the company in crisis, following two deadly crashes in less than five months.

How was it the strategy to keep updating the plane that left to this crisis? The strategy itself is not to blame here, and I very much like the idea to gradually improve a proven model. It was a bad execution of this strategy that left the company in crisis.

In Germany, the national train agency Deutsche Bahn (and its predecessors) basically had a policy for nearly a century to order rolling stock that was designed to be produced for around 40 years. During this production run, the model was gradually improved. Some of the rolling stock designed in the 50ies is still in use, and quite reliable at that [0]. During the 90ies, agency and industry switched to a policy where basically every train generation was newly developed from scratch (for example, the ICE high speed trains). Guess what - you can channel a lot of public money into private hands that way, but bleeding edge technology is not what you want or need when you are trying to build a reliable transportation system.

[0] https://de.wikipedia.org/wiki/N-Wagen

Re: 737 Max: 1960s Design, 1990s Computing Power and Paper Manuals

#75

Post by theclaw »

iliketosleep wrote: post #34

When it comes to flight computers it makes sense to be conservative when it comes to computing power - the goal should be simple, proven, and functional. But when it comes to diagnostics why not use more computing power? As the article states A second electronic system found on other Boeing jets also alerts pilots to unusual or hazardous situations during flight and lays out recommended steps to resolve them. Seems b…

Because new diagnostics mean new pilot training, meaning the new plane is not economical to buy when compared to the competition, meaning no plane at all.

Those other Boeing jets required costly new training. Boeing were trying to build an update to the 737 that did not require this.

Re: 737 Max: 1960s Design, 1990s Computing Power and Paper Manuals

#76

Post by PhantomGremlin »

chmaynard wrote: post #3

The entire management chain that dictated these design compromises should be surgically removed from Boeing and prosecuted for negligence. Of course, that will never happen.

This doesn't get said enough.

Within days of the Lion Air crash, MCAS was strongly suspected to be the problem. And yet Boeing management allowed 157 more people to die in the Ethiopian Airlines crash. And then the Boeing CEO still tried to tell everyone that it was a safe airplane.

The entire top management of Boeing, and the entire board of directors, should be perp-walked out the door.

Of course, that will never happen.

Re: 737 Max: 1960s Design, 1990s Computing Power and Paper Manuals

#78

Post by notahacker »

londons_explore wrote: post #32
AnimalMuppet wrote: post #27

Earlier quoted context omitted.

"Figure out a way to fly the thing in the new, crippled configuration" is hard. Figure out a way that's better than what the human pilot came up with may be even harder.

It's hard, but it's a very measurable problem. You randomly deform the airframe in a physics simulator, then get a real pilot to try to fly the simulated damaged airframe to the nearest airport. You then get an AI to try doing the same. As soon as the AI manages to get to the airport more often than the human, the tech will save lives, on average. My guess is a PhD student could come up with an AI passing the above t…

Your link to ZTE trumpeting the success of an algorithm helping an actual physical model of a quadcopter with a disabled rotor operating in lab conditions to crashland a bit more softly might be interpreted as a hint that the general case of safely landing a stricken aircraft is the sort of problem that probably isn't solved by a single PhD in a year...

Keeping those with enough hubris to say "yeah, shouldn't take long if we've got some sort of sort of simulator to devise scenarios for a neural network to overfit to" about a wide range of failure modes that an entire field has spent decades studying well away from safety critical systems might be one of the more underappreciated aspects of tight regulation.

Re: 737 Max: 1960s Design, 1990s Computing Power and Paper Manuals

#79

Post by StreamBright »

andy_ppp wrote: post #77

Does anyone else here feel aeroplane software should be mandated as being open source? Boeing would have never even dreamed of releasing the 737-Max software in the state it was in and the more eyes you have on things like this the better.

Do you think there are a massive amount of developers out there who are at the same time avionics experts? I just don't see how being opensource would help. You wouldn't be able to even test these software projects because it requires and emulator or actual hardware to run on that you do not have. What would it chage if it was opensource?

Re: 737 Max: 1960s Design, 1990s Computing Power and Paper Manuals

#80

Post by cm2187 »

JauntyHatAngle wrote: post #72
cm2187 wrote: post #61

Earlier quoted context omitted.

No it doesn’t answer the question. If there are two sensors already installed, not requiring change, how come the MCAS only uses one, not both?

The article also states that 2 sensors is not enough as then you have two sensors that can disagree with no way to figure out the correct one.

Yes but at least you know the reading is faulty and avoid applying dangerous commands. Now I don't know if the stall it is meant to avoid is a greater risk than MCAS pushing the plane in the wrong direction.
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