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

151–160 of 280 posts

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

#151

Post by Gibbon1 »

Majromax wrote: post #45
Gibbon1 wrote: post #35

Earlier quoted context omitted.

> and disable the system When you do that you now have an aircraft the pilots aren't certified to fly.

> When you do that you now have an aircraft the pilots aren't certified to fly. It would increase risk. But for that increased risk to materialize into harm, the plane would also need to experience an unlikely, near-edge-of-flight-envelope situation that the working MCAS was intended to handle. This would be comparable to a plane with any other mechanical defect that is discovered in-flight. If the above situation is…

> the plane would also need to experience an unlikely, near-edge-of-flight-envelope situation that the working MCAS was intended to handle.

Failure of the AOA sensor and edge of the flight envelop events can't be assumed to be uncorrelated.

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

#152

Post by inferiorhuman »

cmurf wrote: post #114
nopzor wrote: post #104

Earlier quoted context omitted.

the airplane did not have stable flight characteristics because of its physical design. that’s a hardware problem. MCAS only exists because of that hardware problem. the fact that boeing also did not train or tell pilots about MCAS, in order to make the airplane more financially appealing by retaining the 737 type rating, is a separate (also bad) issue.

Citation needed. FAR 25 applies to all transport category aircraft. The section on stability (§§ 25.171 - 25.181). In exactly what manner is the airplane not stable, with or without MCAS?

From TFA

But a few weeks later, Mr. Wilson and his co-pilot began noticing that something was off, according to a person with direct knowledge of the flights. The Max wasn’t handling well when nearing stalls at low speeds.

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

#154

Post by karmelapple »

kejaed wrote: post #43
kejaed wrote: post #27

I really see this as a failure of the Systems Engineering process. With so many people unaware of the impacts of the changes, it’s up to the systems types to have the big picture view and make sure these sorts of things are taken into account. Especially if as the article says a failure of the AOA sensor on the system would be Hazardous (looks like it was Catastrophic when paired with MCAS in retrospect), that would…

Thinking about this a little more, I also see a failure here in terms of naming things, which I have noticed in my career can be scoffed at but is so important. As the article says, the function of MCAS changed and its operational envelope was greatly expanded. What if, internally at least, the new system was referred to as MCAS2? This is somewhere that things can get political, as was exactly the case with the Max,…

Naming things and communicating changes are all core parts of the Systems Engineering process.

Failing to clearly communicate precisely how big this change was, and not making it extremely clear to all stakeholders what was happening and doing analyses of how these failure modes have changed, is really awful.

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

#155

Post by daodedickinson »

tomglynch wrote: post #148

I posted this as a comment the other day in another Boeing and MCAS discussion. In my research into the topic the saddest bit of information I've seen is the image of the black box data for the flight (the first crash): https://i.imgur.com/WJuhjlO.png You can see from the graph that in the final minutes and seconds, the pilot put insane amounts of force on the control column (aka the yoke) to try to pull the plane ou…

The SEC was given a complete explanation of Bernie Madoff's scam back in the 1990's.

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

#156

Post by karmelapple »

kejaed wrote: post #27

I really see this as a failure of the Systems Engineering process. With so many people unaware of the impacts of the changes, it’s up to the systems types to have the big picture view and make sure these sorts of things are taken into account. Especially if as the article says a failure of the AOA sensor on the system would be Hazardous (looks like it was Catastrophic when paired with MCAS in retrospect), that would…

As a former Systems Engineer who worked on avionics, I would tend to agree; a major change to a system should have at least triggered the integration-level engineers (called the Platform team at my former job) to think hard about potential broad impacts.

It should have resulted in that team actively seeking buy-in, and clear communication that all subsystems comprehended precisely what was changing.

It likely should have triggered some kind of additional scrutiny from the safety organization.

That it didn’t is heartbreaking. It seems like either some common practices were not followed or were rushed.

I can’t see Boeing keeping their CMMI certification level after this news breaks. Certainly some major steps were skipped in the Systems Engineering process.

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

#157

Post by karmelapple »

countbackula wrote: post #132
kejaed wrote: post #43

Earlier quoted context omitted.

Thinking about this a little more, I also see a failure here in terms of naming things, which I have noticed in my career can be scoffed at but is so important. As the article says, the function of MCAS changed and its operational envelope was greatly expanded. What if, internally at least, the new system was referred to as MCAS2? This is somewhere that things can get political, as was exactly the case with the Max,…

Admittedly I have 0 familiarity of the internals of a corporate electrical engineering environment, but this is a logically sound idea that in many other industries is standard. OS 10.02, Apache license v. 2, Archer router xyz Rev 02. What's the limiting factor here in the case of MCAS?

There are definitely different versions of software, each with unique identifiers, such as typical version numbers. There’s also the idea of “flight test ready” software, which is able to go onto a flight, vs software that is only to be used in a lab that is not truly flying in the air and controlling the plane.

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

#158

Post by LoSboccacc »

GoToRO wrote: post #118
kejaed wrote: post #27

I really see this as a failure of the Systems Engineering process. With so many people unaware of the impacts of the changes, it’s up to the systems types to have the big picture view and make sure these sorts of things are taken into account. Especially if as the article says a failure of the AOA sensor on the system would be Hazardous (looks like it was Catastrophic when paired with MCAS in retrospect), that would…

engineers overseeing this work There the thing: nobody wants to pay engineers on par with managers. Maybe one can not manage something he/she can not understand.

> There the thing: nobody wants to pay engineers on par with managers

I used to think like that but I learned in time that the core issue is that engineers rarely know how to present their job in terms of monetary benefit during salary negotiations.

i.e. as an automation engineer I led an initiative that saved a previous employer more than 60k€ yearly using automation and optimizing other validation workflows. as principal engineer at my current job I saved them more than 30k€ yearly by replacing a licensed component with an open source one, filling the feature gaps myself outside of work hours.

these thing get noticed, not just the stuff done but the ability of thinking in money, and unlocks the full engineering potential in salary negotiations

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

#159

Post by bowmessage »

tomglynch wrote: post #148

I posted this as a comment the other day in another Boeing and MCAS discussion. In my research into the topic the saddest bit of information I've seen is the image of the black box data for the flight (the first crash): https://i.imgur.com/WJuhjlO.png You can see from the graph that in the final minutes and seconds, the pilot put insane amounts of force on the control column (aka the yoke) to try to pull the plane ou…

Interesting that there are two angle of attack sensor readings in the black box image when the major issue with MCAS seems to be that it was relying on only a single sensor?

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

#160

Post by eastern »

lugg wrote: post #141
lutorm wrote: post #120

Earlier quoted context omitted.

I think this is false thinking. The 737 is by now a very well tested airframe. Yes, you change some things and there are unexpected results, but the core is sound. Starting over on a completely new design, everything has to be debugged from scratch. This reasoning reminds me of the tendency to argue "this code needs to be thrown out and rewritten from scratch" among software engineers. It's easy to see the flaws, but…

Please, no. This is not the same thing at all. This is like taking your MySQL app and running it against MongoDB with a bunch of hacks to translate the SQL into mongo calls. And then claiming you did all this so you could "avoid a rewrite". Some architectural decisions are far reaching and leaky. This is not the ideal but it often is the ideal trade off. The alternative is decoupling to the nth degree resulting in a…

Exactly.

Changing the position of the engines means it's no longer the same 'tried and tested airframe'.

Post reply on HN