5 ms·

> For example (I am not saying that happened), the engineers designing MCAS didn't expect incorrect AoA data, thinking the checks were done elsewhere. At the sa

> For example (I am not saying that happened), the engineers designing MCAS didn't expect incorrect AoA data, thinking the checks were done elsewhere. At the same time, the "sensors" team thought that raw, unchecked data was expected. The integration guy didn't read the specs correctly (sometimes, it comes down to a single word), didn't catch that, and checked the OK box. His manager, focused on a more pressing issue took that as granted and it went to production. > It is possible that the engineers did an excellent work, but didn't question the specs they had. The integration guy is normally super reliable but he just had a bad day. And his manager handled the other problem beautifully and overlooked the MCAS/AoA because, normally, the integration guy is reliable. A series of small mistakes that ended up in a catastrophe. What you describe here would be a major failure of systems engineering on the project. The systems engineers are responsible for flowing top level requirements down to the individual systems. They are responsible for ensuring the specs the engineering teams receive for their systems are correct, and for handling requests to change said specs. If the spec of the output of the AoA sensors does not match the spec flowed down to other teams on the input from those sensors the systems engineers responsible did not do their jobs. Systems engineers exist to manage complexity like this, to ensure that the various engineering teams across the various disciplines are technically coordinated by providing clear, consistent specs and interfaces for them to work to. If that didn't happen, then I would not say those engineers are competent, let alone smart. It would be especially disappointing to me (as a former systems engineer) if this were the case, as systems engineering is the last place I would expect such incompetence from a company like Boeing. It's at the core of everything they do. I want to address one specific point in a different context. > the engineers designing MCAS didn't expect incorrect AoA data, thinking the checks were done elsewhere You always expect out-of-spec conditions to be a possibility and have something in place to handle those conditions appropriately. To not do so is incompetence bordering on negligence.

mtw 8y ago
2 planes crashes in less than 5 months. So yes, there was either a system engineering failure, or a completely inept decision in choosing an oversized engine for an antic airframe. Your choice.
- ethbro 8y ago
  Or a training requirement failure. Or a UX failure. Or a documentation failure. Or an unrelated failure, given that the RCAs haven't been completed on the crashes. It's amazing the hubris software engineers have in assuming everyone else in an idiot. I am not an expert on aircraft-scale hardware/software codesign projects, aerospace engineering, high-reliability engineering (to aerospace standards), or complex systems analysis. I strongly suspect you, and most of HN, aren't either. Boeing has people with all those skillsets. As does Airbus. As do NTSB and the variety of national certification agencies. So before we toss rocks of certainty around in a comment thread, maybe wait and listen to the experts?
  - bobthepanda 8y ago
    Given that at least some of the expert companies involved have attempted coverups of previous failures before, a little bit of skepticism is healthy. https://en.m.wikipedia.org/wiki/Boeing_737_rudder_issues https://en.m.wikipedia.org/wiki/Boeing_737_rudder_issues Authority should not be free from skepticism, even by people who are not authorities.
    - ethbro 8y ago
      We can agree that not all skepticism is valuable skepticism though? I came across this Rand report on the NTSB [1, 1999?]. The conclusions were not good about the funding & staffing levels vs modern accident load. Partly due to more incidents, but moreso due to increased systems complexity per incident. So the NTSB, with a budget of around USD$100M, takes multiple years to deliver a report. And they're a professional worldwide standard on accident investigation. Suffice to say, we're not going to crack this case open on HN. Which isn't to say it isn't productive to debate the relative merits of different regulatory approaches, takeaways for other disciplines, lessons learned, and all manner of things. But let's just have some humility in pretending we're all experts on everything [2]. [1] https://www.rand.org/content/dam/rand/pubs/monograph_reports/MR1122z1/MR1122.1.sum.pdf https://www.rand.org/content/dam/rand/pubs/monograph_reports... [2] Though in fairness, I wouldn't be surprised if there were at least one expert on any given topic here. You folks are awesome.
ken 8y ago
With their last new aircraft, this happened many times. For example, they discovered that the pieces didn't fit together: https://www.seattletimes.com/business/boeing-finds-787-pieces-arent-quite-a-perfect-fit/ https://www.seattletimes.com/business/boeing-finds-787-piece... I agree that someone with a title like Systems Engineer should be responsible for such issues, but (having worked at Boeing) not every group has systems engineers overseeing their work. Or they're working in a different city and you get a phone conference with them once a month. This should be no surprise. Conway's Law in action. You can look at the issues that Boeing has and guess to a reasonable degree of accuracy what their organizational structures look like. > You always expect out-of-spec conditions to be a possibility and have something in place to handle those conditions appropriately. To not do so is incompetence bordering on negligence. I don't think it's possible to build an airplane if you have to expect this from every system. Any flying machine has many single points of failure. An F-15 once famously flew and landed after losing a wing. This is clearly out-of-spec but no aircraft considers this condition a realistic possibility or has contingency procedures for it. Exercise for the reader (and maybe a good interview question for a manager): draw the organizational structure for a team to design and manufacture a new airliner. List the single points of failure on the aircraft, and point to who is responsible for them. Would you fly on this? What did you miss?

mtw 8y ago

2 planes crashes in less than 5 months. So yes, there was either a system engineering failure, or a completely inept decision in choosing an oversized engine for an antic airframe. Your choice.

ethbro 8y ago
Or a training requirement failure. Or a UX failure. Or a documentation failure. Or an unrelated failure, given that the RCAs haven't been completed on the crashes. It's amazing the hubris software engineers have in assuming everyone else in an idiot. I am not an expert on aircraft-scale hardware/software codesign projects, aerospace engineering, high-reliability engineering (to aerospace standards), or complex systems analysis. I strongly suspect you, and most of HN, aren't either. Boeing has people with all those skillsets. As does Airbus. As do NTSB and the variety of national certification agencies. So before we toss rocks of certainty around in a comment thread, maybe wait and listen to the experts?
- bobthepanda 8y ago
  Given that at least some of the expert companies involved have attempted coverups of previous failures before, a little bit of skepticism is healthy. https://en.m.wikipedia.org/wiki/Boeing_737_rudder_issues https://en.m.wikipedia.org/wiki/Boeing_737_rudder_issues Authority should not be free from skepticism, even by people who are not authorities.
  - ethbro 8y ago
    We can agree that not all skepticism is valuable skepticism though? I came across this Rand report on the NTSB [1, 1999?]. The conclusions were not good about the funding & staffing levels vs modern accident load. Partly due to more incidents, but moreso due to increased systems complexity per incident. So the NTSB, with a budget of around USD$100M, takes multiple years to deliver a report. And they're a professional worldwide standard on accident investigation. Suffice to say, we're not going to crack this case open on HN. Which isn't to say it isn't productive to debate the relative merits of different regulatory approaches, takeaways for other disciplines, lessons learned, and all manner of things. But let's just have some humility in pretending we're all experts on everything [2]. [1] https://www.rand.org/content/dam/rand/pubs/monograph_reports/MR1122z1/MR1122.1.sum.pdf https://www.rand.org/content/dam/rand/pubs/monograph_reports... [2] Though in fairness, I wouldn't be surprised if there were at least one expert on any given topic here. You folks are awesome.

ken 8y ago

With their last new aircraft, this happened many times. For example, they discovered that the pieces didn't fit together: https://www.seattletimes.com/business/boeing-finds-787-pieces-arent-quite-a-perfect-fit/ https://www.seattletimes.com/business/boeing-finds-787-piece... I agree that someone with a title like Systems Engineer should be responsible for such issues, but (having worked at Boeing) not every group has systems engineers overseeing their work. Or they're working in a different city and you get a phone conference with them once a month. This should be no surprise. Conway's Law in action. You can look at the issues that Boeing has and guess to a reasonable degree of accuracy what their organizational structures look like. > You always expect out-of-spec conditions to be a possibility and have something in place to handle those conditions appropriately. To not do so is incompetence bordering on negligence. I don't think it's possible to build an airplane if you have to expect this from every system. Any flying machine has many single points of failure. An F-15 once famously flew and landed after losing a wing. This is clearly out-of-spec but no aircraft considers this condition a realistic possibility or has contingency procedures for it. Exercise for the reader (and maybe a good interview question for a manager): draw the organizational structure for a team to design and manufacture a new airliner. List the single points of failure on the aircraft, and point to who is responsible for them. Would you fly on this? What did you miss?