How Boeing, FAA certified the suspect 737 MAX flight control system • Hacker News Board

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#61

Post by wnevets » Mon, Mar 18, 2019, 5:56 PM UTC

MockObject wrote: post #52

wnevets wrote: post #30

>FAA for pushing engineers to 'delegate' reviews of certain components back to Boeing themselves. How much more proof do we need as a society that self regulation is a fool's errand?

If we're discussing a failure of the FAA, that's the right context to bash regulation, not "self regulation".

That is misleading at best. The FAA was instructed to let the industry to regulate itself more, a typical republican/libertarian belief. Boeing being allowed to self regulated created this mess.

https://www.forbes.com/sites/marisagarcia/2019/03/18/did-tru...

>Still, the US DOT mandated that the FAA begin the process of review to reduce regulations. The FAA assigned this task to ARAC, effectively putting the question of what rules to cut and which to eliminate before creating new ones in the hands of a body that includes representatives from manufacturers and airlines.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#62

Post by tafda » Mon, Mar 18, 2019, 6:00 PM UTC

ajross wrote: post #55

mimixco wrote: post #10

Notable and disturbing here is the lack of Max simulators in existence. It looks like neither Lion Air nor Ethiopian nor any US airline had access to one. Also linked in this article is the original FAA table of differences between the Max and other 737 models. It makes no metion of MCAS.

Yeah. As much blame as Boeing and the FAA certification process seems to deserve here, it's worth pointing out how much of the cascade of failures is in the airlines and cockpits too. I mean, yes, the trim system was being driven by input from a single nonredundant sensor, which is a violation of the kind of engineering for failure process that airliners should be designed in. But at the same time that trim system is…

Not true.

https://www.seattletimes.com/business/boeing-aerospace/faile... Quote:

The discrepancy over this number is magnified by another element in the System Safety Analysis: The limit of the system’s authority to move the tail applies each time MCAS is triggered. And it can be triggered multiple times, as it was on the Lion Air flight.

One current FAA safety engineer said that every time the pilots on the Lion Air flight reset the switches on their control columns to pull the nose back up, MCAS would have kicked in again and “allowed new increments of 2.5 degrees.”

“So once they pushed a couple of times, they were at full stop,” meaning at the full extent of the tail swivel, he said.

Peter Lemme, a former Boeing flight controls engineer who is now an avionics and satellite-communications consultant, said that because MCAS reset each time it was used, “it effectively has unlimited authority.”

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#63

Post by penagwin » Mon, Mar 18, 2019, 6:02 PM UTC

stcredzero wrote: post #22

There is a big difference between how you behave when you're calm, vs how you behave when you're under stress. Basically, you start hitting sub-sentient "defaults." You default to your training. You default to inherited flight or fight behaviors. Emergency procedures and training need to be designed with this in mind, or they will fail. (Presentation preparation is like this. My last presentation failed because by se…

Unrelated but "Fight or Flight" is actually a great pun for pilots that I never thought of before.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#64

Post by MockObject » Mon, Mar 18, 2019, 6:05 PM UTC

wnevets wrote: post #61

MockObject wrote: post #52

Earlier quoted context omitted.

If we're discussing a failure of the FAA, that's the right context to bash regulation, not "self regulation".

That is misleading at best. The FAA was instructed to let the industry to regulate itself more, a typical republican/libertarian belief. Boeing being allowed to self regulated created this mess. https://www.forbes.com/sites/marisagarcia/2019/03/18/did-tru... >Still, the US DOT mandated that the FAA begin the process of review to reduce regulations. The FAA assigned this task to ARAC, effectively putting the question…

But an inherent bug of government regulation is that it's always vulnerable to lobbying like you cited. So it's still a failure of regulation, except one that is permanent and unsurprising.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#65

Post by ajross » Mon, Mar 18, 2019, 6:10 PM UTC

tafda wrote: post #62

ajross wrote: post #55

Earlier quoted context omitted.

Yeah. As much blame as Boeing and the FAA certification process seems to deserve here, it's worth pointing out how much of the cascade of failures is in the airlines and cockpits too. I mean, yes, the trim system was being driven by input from a single nonredundant sensor, which is a violation of the kind of engineering for failure process that airliners should be designed in. But at the same time that trim system is…

Not true. https://www.seattletimes.com/business/boeing-aerospace/faile... Quote: The discrepancy over this number is magnified by another element in the System Safety Analysis: The limit of the system’s authority to move the tail applies each time MCAS is triggered. And it can be triggered multiple times, as it was on the Lion Air flight. One current FAA safety engineer said that every time the pilots on the Lion Air…

Yes true.[1]

You're misunderstanding that quote. It's talking about "authority" in the sense of software's authorization to move the trim tab, not the aerodynamic authority of the tailplane.

The 737 has a 60 year old, very conventional elevator with a trim tab. The tab changes the resting angle of the overall elevator, and thus the "center point" of tailplane force on the airframe. Being out of trim means that the aircraft might naturally want to pitch up or down, and forces the pilot to apply to force to the stick (which moves the elevator, not the trim tab!) to correct it.

This stick force can be significant and surprising, but it's designed to (and the certification surely requires it to) be achievable by a pilot under all conditions. That is: it's not supposed to be possible for any trim failure on a 737 to render an aircraft uncontrollable, and I don't see any assertion in the analysis of the MAX 8 that changes that.

At the end of the day, what happened here is that the aircraft had a runaway trim failure. That was a failure that was understood and forseen (albeit not under software control) in the aircraft's original design, and the redundancy to treat it was the pilot's physical ability to override the trim. This was supposed to have been a recoverable failure within the cockpit, and it wasn't.

[1] Style note: why do people do this on the internet? Ah hah! You fool! You are WRONG! Stuff is complicated folks, be nice, assume competence, assume lack of malice, try to teach and not argue.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#66

Post by wnevets » Mon, Mar 18, 2019, 6:12 PM UTC

MockObject wrote: post #64

wnevets wrote: post #61

Earlier quoted context omitted.

That is misleading at best. The FAA was instructed to let the industry to regulate itself more, a typical republican/libertarian belief. Boeing being allowed to self regulated created this mess. https://www.forbes.com/sites/marisagarcia/2019/03/18/did-tru... >Still, the US DOT mandated that the FAA begin the process of review to reduce regulations. The FAA assigned this task to ARAC, effectively putting the question…

But an inherent bug of government regulation is that it's always vulnerable to lobbying like you cited. So it's still a failure of regulation, except one that is permanent and unsurprising.

Are you arguing that it was a failure of the government regulation by allowing the self regulation that caused the mess?

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#67

Post by chrismeller » Mon, Mar 18, 2019, 6:13 PM UTC

ineedasername wrote: post #57

linuxftw wrote: post #44

Earlier quoted context omitted.

The free market answer would be insurance. As an individual, you probably want some kind of life insurance in the event of catastrophe. Your insurance carrier may require you only ride in such and such certified aircraft (eg, an aircraft that is insured against loss of life). An aircraft may only obtain insurance if it meets certain requirements, etc. Unfortunately, we've got a regulatory body asleep at the wheel, te…

Looking back a hundred or more years when the market was more free, your vision of how things might work does not hold. There were no insurance markets for potential injury due to riding a horse, no private certification of stables that lent horses to ensure animals were fit and free of issues of temperament that might cause them to throw a rider. The free market is not a panacea that solves every problem. It does so…

A horse was also a much less complex animal (literally) than a 737. Using that as a justification for the lack of an insurance market is just wrong...

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#68

Post by ken » Mon, Mar 18, 2019, 6:16 PM UTC

GuB-42 wrote: post #49

linuxftw wrote: post #28

This article seems to be second-hand reporting some of the information originally broken here [1]. There's a lot of damning information, not only for Boeing, but also a lot of negligence at the FAA for pushing engineers to 'delegate' reviews of certain components back to Boeing themselves. [1] https://www.seattletimes.com/business/boeing-aerospace/faile...

AFAIK, the FAA, like many regulating bodies take everything at face value, making sure they are not getting lied to isn't their jobs. An audit usually goes like: "I see that you mentioned a change in document X, show me the corresponding test report", "who is responsible for that part?", "does document Y match document X, as required by norm Z?". They will never check that you actually did the tests, or that the anal…

Exactly. I worked at Boeing for a couple years (on a different aircraft project, on software tools that would never fly on an aircraft), and my boss made it very clear that our job was not to make sure the airplane didn't crash. It was to make sure if anything went wrong, we had the proper paper trail.

As a software person, this led to some results that seemed rather counterintuitive.

Then again, this level of detachment seems necessary for complex systems. The chef at your favorite restaurant doesn't personally test all raw ingredients to ensure they're safe. They get them from a reputable source, and make sure they're stored and prepared properly when under the restaurant's care.

I suspect that this concept is foreign to much of the software world (and hopefully only temporarily) because our raw ingredients are so low quality, and there's no regulation or certification. Half the libraries I'm using (even first-party ones) have significant bugs that I have to work around. If instead of workarounds I just said "That bug you found is actually a bug in ", my app would be completely unusable, and there's be no upstream pressure for these libraries to ever get fixed.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#69

Post by WalterBright » Mon, Mar 18, 2019, 6:16 PM UTC

ineedasername wrote: post #57

linuxftw wrote: post #44

Earlier quoted context omitted.

The free market answer would be insurance. As an individual, you probably want some kind of life insurance in the event of catastrophe. Your insurance carrier may require you only ride in such and such certified aircraft (eg, an aircraft that is insured against loss of life). An aircraft may only obtain insurance if it meets certain requirements, etc. Unfortunately, we've got a regulatory body asleep at the wheel, te…

Looking back a hundred or more years when the market was more free, your vision of how things might work does not hold. There were no insurance markets for potential injury due to riding a horse, no private certification of stables that lent horses to ensure animals were fit and free of issues of temperament that might cause them to throw a rider. The free market is not a panacea that solves every problem. It does so…

> no private certification of stables that lent horses to ensure animals were fit and free of issues of temperament that might cause them to throw a rider.

Probably because the culture of the time was that everyone knew horses were dangerous and if you borrowed a horse and it threw you, it was your fault, not the lender's.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#70

Post by WalterBright » Mon, Mar 18, 2019, 6:22 PM UTC

jcims wrote: post #35

Unvetted image comparison of the cockpits 737 MAX 8 Cockpit - https://i2.wp.com/thepointsguy.com/wp-content/uploads/2017/0... 737 800 Cockpit - https://i.imgur.com/eRULoST.jpg I don't really know my way around an airliner but the key displays seem to be quite different and there's a lot fewer knobs on the MAX 8.

Note the two black wheels on either side of the center console. These spin and make a loud clacking sound when the stabilizer trim is running. It should have been quite obvious that the trim action was what was causing the pitch down.