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> It isn’t like they are making decisions with the intent of compromising safety. That really is actually exactly what they did and are doing. When you don’t d

by nabdab 7y ago

> It isn’t like they are making decisions with the intent of compromising safety. That really is actually exactly what they did and are doing. When you don’t do tests because you are confident something will pass, that doesn’t change that you aren’t testing, and you are compromising quality on the basis of productivity. Here Boeing decided to go against the safe practice because that would have classified the plane as a different plane and incurred huge costs, but it would have increased safety and likely avoided the accidents. They did compromise safety, they did so thinking that it wouldn’t matter because the overall safety would be good enough for no one to notice, but that gamble failed and others paid their lives to cover the bet.

kingkongjaffa 7y ago
There's a level of engineering judgement involved here though. If product A has passed testing and I made minor changes and made a product B if I can avoid running the whole battery of tests as if product B is brand new and not derivative then I totally will and Aerospace and Automotive operate like this all the time in every country in the world it's not poor practice.
WalterBright 7y ago
On the other hand, making X behave like Y, where Y is something pilots are very used to, is safer.
- salawat 7y ago
  MD-11 and now MAX raise questions on the execution of that. Pilots have to understand the how and why the different thing can fly like the old thing so that when something goes wrong and that invariant is inevitably violated, they aren't caught off guard.
  - WalterBright 7y ago
    Since the advent of powered flight controls, they've been shaped to give desired handling characteristics. For example, in the 70's control forces were lightened considerably to accommodate female pilots, though many were concerned this would lead to overcontrolling the airplane by the male pilots. Human factors design is nowhere near easy or settled science, not in iphone design nor in flight controls design.
    - salawat 7y ago
      >Human factors design is nowhere near easy or settled science, not in iphone design nor in flight controls design. Given. The issue I keep coming back to is the flawed regard for human factors in MCAS. They paid enough attention to squeak by the artificial feel, but then completely ignored the fact that a pilot can't react or stay ahead of something on a plane that no one tells them even exists. Then when it became evident it might be a problem, they back pedaled, putting as much blame on the operators as they could. They thought about it. They decided "Nah, they don't need to know." At some point the tech pilot even expressed concerns over the system, yet was still pressured to keep it out of the manual...why? No one in good faith has anything to gain from that system's implementation details seeing the light of day. Unless of course, there was some other motivation, like avoiding the costs of compliance at some point.
      - WalterBright 7y ago
        Boeing relied on the pilot noticing runaway stabilizer and doing what they're trained to do on runaway stabilizer - turn off the trim motors. The first of the 3 sets of pilots did this, and landed without incident. The next set overrode MCAS successfully 25 times, inexplicably did not turn off the trim, did not override it the last time, and crashed. The last set successfully countered MCAS twice, then turned off the trim. They did not follow the directions on Boeing's Flight Crew Operations Manual Bulletin: "Uncommanded Nose-Down Stabilizer Trim Due to Erroneous Angle Of Attack During Manual Flight Only", which the FAA turned into a mandatory emergency airworthiness directive. -- Aviation Week, Aug 19, 2019
        salawat 7y ago
        >The first of the 3 sets of pilots did this, and landed without incident. Extra pilot in cockpit. Not a CRM situation that's a given. >The next set overrode MCAS successfully 25 times, inexplicably did not turn off the trim, did not override it the last time, and crashed. They didn't know why the trim was kicking in in the first place, and the senior pilot was the one countering the trim. He handed it off to the junior pilot to sift through the manual, which ironically, would have been futile anyway as MCAS was dropped from the manual. The behavior did not present as a classic stabilizer runaway. Other pilots interviewed also pointed this out including in the Australian 60 minutes expose on the 737 MAX if I recall correctly, so I'm not sure that the same definition you're fond of is universally shared amongst pilots. Bad priming is also a human factor that is catastrophically lacking among other things not being taken into account. Furthermore, if pilots were really held to account for knowing the hardware they're operating, they should have known the nature of the trim switch change between the 737 NG and MAX, and the consequences thereof; that wasn't included. >The last set successfully countered MCAS twice, then turned off the trim. They did not follow the directions on Boeing's Flight Crew Operations Manual Bulletin: "Uncommanded Nose-Down Stabilizer Trim Due to Erroneous Angle Of Attack During Manual Flight Only", which the FAA turned into a mandatory emergency airworthiness directive. They did follow it actually, but also notice the Note toward the end (see the appendix in the Ethiopian preliminary report. The line reads) >Note: Initially higher control forces may be needed to overcome any stabilizer nose down trim already applied. Electric stabilizer trim can be used to neutralize control column pitch before moving the STAB TRIM CUTOUT switches to CUTOUT. Now. There is something to be said for "Gee, did they read it", but considering the bloody thing includes a disclaimer that the AFM supersedes the bulletin due to not being approved by the FAA, the note being presented outside the main content of the directive, and the notification beeping issued in November, I don't have high hopes for the real effectiveness of the bulletin at clearly communicating the severity of the problem, something which simulator time would have made plain and obvious. Then again, that's just me.

by nabdab 7y ago

kingkongjaffa 7y ago

There's a level of engineering judgement involved here though. If product A has passed testing and I made minor changes and made a product B if I can avoid running the whole battery of tests as if product B is brand new and not derivative then I totally will and Aerospace and Automotive operate like this all the time in every country in the world it's not poor practice.

WalterBright 7y ago

On the other hand, making X behave like Y, where Y is something pilots are very used to, is safer.

salawat 7y ago
MD-11 and now MAX raise questions on the execution of that. Pilots have to understand the how and why the different thing can fly like the old thing so that when something goes wrong and that invariant is inevitably violated, they aren't caught off guard.
- WalterBright 7y ago
  Since the advent of powered flight controls, they've been shaped to give desired handling characteristics. For example, in the 70's control forces were lightened considerably to accommodate female pilots, though many were concerned this would lead to overcontrolling the airplane by the male pilots. Human factors design is nowhere near easy or settled science, not in iphone design nor in flight controls design.
  - salawat 7y ago
    >Human factors design is nowhere near easy or settled science, not in iphone design nor in flight controls design. Given. The issue I keep coming back to is the flawed regard for human factors in MCAS. They paid enough attention to squeak by the artificial feel, but then completely ignored the fact that a pilot can't react or stay ahead of something on a plane that no one tells them even exists. Then when it became evident it might be a problem, they back pedaled, putting as much blame on the operators as they could. They thought about it. They decided "Nah, they don't need to know." At some point the tech pilot even expressed concerns over the system, yet was still pressured to keep it out of the manual...why? No one in good faith has anything to gain from that system's implementation details seeing the light of day. Unless of course, there was some other motivation, like avoiding the costs of compliance at some point.
    - WalterBright 7y ago
      Boeing relied on the pilot noticing runaway stabilizer and doing what they're trained to do on runaway stabilizer - turn off the trim motors. The first of the 3 sets of pilots did this, and landed without incident. The next set overrode MCAS successfully 25 times, inexplicably did not turn off the trim, did not override it the last time, and crashed. The last set successfully countered MCAS twice, then turned off the trim. They did not follow the directions on Boeing's Flight Crew Operations Manual Bulletin: "Uncommanded Nose-Down Stabilizer Trim Due to Erroneous Angle Of Attack During Manual Flight Only", which the FAA turned into a mandatory emergency airworthiness directive. -- Aviation Week, Aug 19, 2019
      - salawat 7y ago
        >The first of the 3 sets of pilots did this, and landed without incident. Extra pilot in cockpit. Not a CRM situation that's a given. >The next set overrode MCAS successfully 25 times, inexplicably did not turn off the trim, did not override it the last time, and crashed. They didn't know why the trim was kicking in in the first place, and the senior pilot was the one countering the trim. He handed it off to the junior pilot to sift through the manual, which ironically, would have been futile anyway as MCAS was dropped from the manual. The behavior did not present as a classic stabilizer runaway. Other pilots interviewed also pointed this out including in the Australian 60 minutes expose on the 737 MAX if I recall correctly, so I'm not sure that the same definition you're fond of is universally shared amongst pilots. Bad priming is also a human factor that is catastrophically lacking among other things not being taken into account. Furthermore, if pilots were really held to account for knowing the hardware they're operating, they should have known the nature of the trim switch change between the 737 NG and MAX, and the consequences thereof; that wasn't included. >The last set successfully countered MCAS twice, then turned off the trim. They did not follow the directions on Boeing's Flight Crew Operations Manual Bulletin: "Uncommanded Nose-Down Stabilizer Trim Due to Erroneous Angle Of Attack During Manual Flight Only", which the FAA turned into a mandatory emergency airworthiness directive. They did follow it actually, but also notice the Note toward the end (see the appendix in the Ethiopian preliminary report. The line reads) >Note: Initially higher control forces may be needed to overcome any stabilizer nose down trim already applied. Electric stabilizer trim can be used to neutralize control column pitch before moving the STAB TRIM CUTOUT switches to CUTOUT. Now. There is something to be said for "Gee, did they read it", but considering the bloody thing includes a disclaimer that the AFM supersedes the bulletin due to not being approved by the FAA, the note being presented outside the main content of the directive, and the notification beeping issued in November, I don't have high hopes for the real effectiveness of the bulletin at clearly communicating the severity of the problem, something which simulator time would have made plain and obvious. Then again, that's just me.