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> You could have made similar arguments after every air crash that was caused by a design flaw. I'm not really convinced this is true. For instance, in the cla

> You could have made similar arguments after every air crash that was caused by a design flaw. I'm not really convinced this is true. For instance, in the classic case of de Havilland Comets brought down by square windows, I think it was an honest mistake that happened because pressurized cabins were new-ish tech. They worked to understand the problem and fixed the design. Nobody was trying to cut corners AFAIK (no pun intended). I guess we could make another category where an iffy design is made to fail by corner-cutting on the part of the airlines, as in the MD-80 pitch trim jackscrew issues. The MAX is a case of the actual aircraft manufacturer explicitly compromising the design of a safety feature because they knew it would help them sell more planes (due to avoiding training/recertification requirements). IIRC, the investigation revealed a consistent pattern of negligence and outright malfeasance on Boeing's part to this effect. I wouldn't say this kind of thing has never happened before, but off the top of my head I have to assume it's pretty rare.

WalterBright 6y ago
> The MAX is a case of the actual aircraft manufacturer explicitly compromising the design of a safety feature because they knew it would help them sell more planes The error was not in the concept of the MAX nor the concept of the MCAS. The problem was twofold: 1. MCAS should have used inputs from both AOA sensors, rather than just one. MCAS had too much authority over the travel, and it should have deactivated itself if the pilots repeatedly countermanded it. 2. The pilots were not trained properly in emergency procedures with the stab trim. Boeing put out an Emergency Airworthiness Directive after the first crash with explicit instructions on how to deal with it, but the EA pilots did not follow those instructions. https://theaircurrent.com/wp-content/uploads/2018/11/B737-MAX-AD-1107.pdf https://theaircurrent.com/wp-content/uploads/2018/11/B737-MA...
- dTal 6y ago
  >The pilots were not trained properly in emergency procedures with the stab trim. Boeing put out an Emergency Airworthiness Directive after the first crash with explicit instructions on how to deal with it, but the EA pilots did not follow those instructions. If the planes are still crashing after the "problem" was fixed, then that wasn't the problem. (Specifically - the "emergency procedures" in question are "what to do if your plane randomly decides to fly you into the ground". The only way to save your skin is to take a specific emergency action within a time window of a few seconds. This is not a reasonable design.)
  - WalterBright 6y ago
    Neither crash was within a few seconds. The EA crew fought it for 5 minutes, the LA crew 25 minutes. -- Aviation Week, Sep 1, 2019 As for being an emergency, yes it was, and dealing with emergencies is most of pilot training. Dealing with runaway trim (which is how this failure exhibited) is part of that training. The Emergency Airworthiness Directive reiterated what the procedure was for runaway trim. Runaway trim is so serious that it is a "memory item" meaning the pilots know how to deal with it without needing to consult a checklist. While runaway trim should never happen, it is reasonable to expect the pilots to deal with it properly.
    - dTal 6y ago
      >Neither crash was within a few seconds That's not what I said. If you don't take mitigating actions within a time window of a few seconds, you are locked into an unrecoverable situation - however long you might fight it afterwards. Specifically - the trim wheel is too stiff to correct if the stabilizer is loaded, so if the MCAS is allowed to wind the stabilizer to its extreme position, the pilot must - after disabling the MCAS (and therefore also the electric trim) - unload the control column to correct the situation, which will send the aircraft straight into the ground. Hence the undulations seen in the flight paths of the crashed aircraft. The MCAS was designed under the assumption that pilots would respond to unexpected activation within 3 seconds: https://www.seattletimes.com/seattle-news/times-watchdog/the-inside-story-of-mcas-how-boeings-737-max-system-gained-power-and-lost-safeguards/ https://www.seattletimes.com/seattle-news/times-watchdog/the...
      - WalterBright 6y ago
        The Seattle Times hasn't a good track record of accurately reporting the facts on aviation stories. Their aviation reporter does not read or comprehend his cited sources. The EA crew dealt with the situation for 5 minutes, the LA crew for 25 minutes. Both crews used the electric trim switches to restore normal trim, multiple times. The trim switches are on the control column right under one's thumb. All the reports saying it was impossible or unreasonable or there wasn't enough time to do this are false, as both crews did it. I strongly recommend a more reputable source, like Aviation Week 19-Sep-2019. Also an original source, https://theaircurrent.com/wp-content/uploads/2018/11/B737-MAX-AD-1107.pdf https://theaircurrent.com/wp-content/uploads/2018/11/B737-MA... There's also an often-cited article going around that's written by a Cessna pilot. His opinions on how jet aircraft should be designed have little to do with reality - high altitude high speed jets are very, very different from a low and slow Cessna. (The Air Force thought it would be easy to transition their experienced propeller pilots to jets. A lot of crashes and dead pilots changed their minds.)
- eganist 6y ago
  > The error was not in the concept of the MAX nor the concept of the MCAS. The reason MCAS was introduced in the first place was because the platform that Boeing chose to extend (to avoid recertification requirements) was unstable as a result of the introduction of CFM's new LEAP engines. They insisted on correcting an emergent hardware defect with software in order to reuse an old platform to compete against a surprise threat from Airbus rather than design an inherently safe, novel platform. All to save time and money getting to production. I.e. all for profit. As for the emergency procedures Boeing drafted after Lion Air, they apparently were attempted: https://www.seattletimes.com/business/boeing-aerospace/boeings-emergency-procedure-for-737-max-may-have-failed-on-ethiopian-flight/ https://www.seattletimes.com/business/boeing-aerospace/boein... — and more recently https://www.theguardian.com/world/2019/apr/04/ethiopian-airlines-crash-pilots-followed-procedure-report-finds https://www.theguardian.com/world/2019/apr/04/ethiopian-airl...
  - WalterBright 6y ago
    > was unstable No, it was not unstable. It just behaved differently enough that some additional pilot training would have been needed without MCAS. > rather than design an inherently safe All jetliners are unstable and require active augmentation. > they apparently were attempted No, they were not. The procedure is: 1. trim to normal with the electric trim switches 2. turn off the stab trim switches. That's it. https://theaircurrent.com/wp-content/uploads/2018/11/B737-MAX-AD-1107.pdf https://theaircurrent.com/wp-content/uploads/2018/11/B737-MA... The LA crew never turned off the trim after trimming to normal. The EA made a different mistake - turning off the trim when it was too far from neutral. Neither the Seattle Times nor The Guardian are reliable sources on aviation. Aviation Week is a lot better. The Times author apparently did not read the EAD he cited. I'll quote from it the relevant bit: https://theaircurrent.com/wp-content/uploads/2018/11/B737-MAX-AD-1107.pdf https://theaircurrent.com/wp-content/uploads/2018/11/B737-MA... "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 forces before moving the STAB TRIM CUTOUT switches to CUTOUT. Manual stabilizer trim can be used before and after the STAB TRIM CUTOUT switches are moved to CUTOUT." Note that the flight data recorder showed that both crews had moved the trim back to normal with the trim switches, and neither thought to then turn it off.

WalterBright 6y ago

> The MAX is a case of the actual aircraft manufacturer explicitly compromising the design of a safety feature because they knew it would help them sell more planes The error was not in the concept of the MAX nor the concept of the MCAS. The problem was twofold: 1. MCAS should have used inputs from both AOA sensors, rather than just one. MCAS had too much authority over the travel, and it should have deactivated itself if the pilots repeatedly countermanded it. 2. The pilots were not trained properly in emergency procedures with the stab trim. Boeing put out an Emergency Airworthiness Directive after the first crash with explicit instructions on how to deal with it, but the EA pilots did not follow those instructions. https://theaircurrent.com/wp-content/uploads/2018/11/B737-MAX-AD-1107.pdf https://theaircurrent.com/wp-content/uploads/2018/11/B737-MA...

dTal 6y ago
>The pilots were not trained properly in emergency procedures with the stab trim. Boeing put out an Emergency Airworthiness Directive after the first crash with explicit instructions on how to deal with it, but the EA pilots did not follow those instructions. If the planes are still crashing after the "problem" was fixed, then that wasn't the problem. (Specifically - the "emergency procedures" in question are "what to do if your plane randomly decides to fly you into the ground". The only way to save your skin is to take a specific emergency action within a time window of a few seconds. This is not a reasonable design.)
- WalterBright 6y ago
  Neither crash was within a few seconds. The EA crew fought it for 5 minutes, the LA crew 25 minutes. -- Aviation Week, Sep 1, 2019 As for being an emergency, yes it was, and dealing with emergencies is most of pilot training. Dealing with runaway trim (which is how this failure exhibited) is part of that training. The Emergency Airworthiness Directive reiterated what the procedure was for runaway trim. Runaway trim is so serious that it is a "memory item" meaning the pilots know how to deal with it without needing to consult a checklist. While runaway trim should never happen, it is reasonable to expect the pilots to deal with it properly.
  - dTal 6y ago
    >Neither crash was within a few seconds That's not what I said. If you don't take mitigating actions within a time window of a few seconds, you are locked into an unrecoverable situation - however long you might fight it afterwards. Specifically - the trim wheel is too stiff to correct if the stabilizer is loaded, so if the MCAS is allowed to wind the stabilizer to its extreme position, the pilot must - after disabling the MCAS (and therefore also the electric trim) - unload the control column to correct the situation, which will send the aircraft straight into the ground. Hence the undulations seen in the flight paths of the crashed aircraft. The MCAS was designed under the assumption that pilots would respond to unexpected activation within 3 seconds: https://www.seattletimes.com/seattle-news/times-watchdog/the-inside-story-of-mcas-how-boeings-737-max-system-gained-power-and-lost-safeguards/ https://www.seattletimes.com/seattle-news/times-watchdog/the...
    - WalterBright 6y ago
      The Seattle Times hasn't a good track record of accurately reporting the facts on aviation stories. Their aviation reporter does not read or comprehend his cited sources. The EA crew dealt with the situation for 5 minutes, the LA crew for 25 minutes. Both crews used the electric trim switches to restore normal trim, multiple times. The trim switches are on the control column right under one's thumb. All the reports saying it was impossible or unreasonable or there wasn't enough time to do this are false, as both crews did it. I strongly recommend a more reputable source, like Aviation Week 19-Sep-2019. Also an original source, https://theaircurrent.com/wp-content/uploads/2018/11/B737-MAX-AD-1107.pdf https://theaircurrent.com/wp-content/uploads/2018/11/B737-MA... There's also an often-cited article going around that's written by a Cessna pilot. His opinions on how jet aircraft should be designed have little to do with reality - high altitude high speed jets are very, very different from a low and slow Cessna. (The Air Force thought it would be easy to transition their experienced propeller pilots to jets. A lot of crashes and dead pilots changed their minds.)
eganist 6y ago
> The error was not in the concept of the MAX nor the concept of the MCAS. The reason MCAS was introduced in the first place was because the platform that Boeing chose to extend (to avoid recertification requirements) was unstable as a result of the introduction of CFM's new LEAP engines. They insisted on correcting an emergent hardware defect with software in order to reuse an old platform to compete against a surprise threat from Airbus rather than design an inherently safe, novel platform. All to save time and money getting to production. I.e. all for profit. As for the emergency procedures Boeing drafted after Lion Air, they apparently were attempted: https://www.seattletimes.com/business/boeing-aerospace/boeings-emergency-procedure-for-737-max-may-have-failed-on-ethiopian-flight/ https://www.seattletimes.com/business/boeing-aerospace/boein... — and more recently https://www.theguardian.com/world/2019/apr/04/ethiopian-airlines-crash-pilots-followed-procedure-report-finds https://www.theguardian.com/world/2019/apr/04/ethiopian-airl...
- WalterBright 6y ago
  > was unstable No, it was not unstable. It just behaved differently enough that some additional pilot training would have been needed without MCAS. > rather than design an inherently safe All jetliners are unstable and require active augmentation. > they apparently were attempted No, they were not. The procedure is: 1. trim to normal with the electric trim switches 2. turn off the stab trim switches. That's it. https://theaircurrent.com/wp-content/uploads/2018/11/B737-MAX-AD-1107.pdf https://theaircurrent.com/wp-content/uploads/2018/11/B737-MA... The LA crew never turned off the trim after trimming to normal. The EA made a different mistake - turning off the trim when it was too far from neutral. Neither the Seattle Times nor The Guardian are reliable sources on aviation. Aviation Week is a lot better. The Times author apparently did not read the EAD he cited. I'll quote from it the relevant bit: https://theaircurrent.com/wp-content/uploads/2018/11/B737-MAX-AD-1107.pdf https://theaircurrent.com/wp-content/uploads/2018/11/B737-MA... "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 forces before moving the STAB TRIM CUTOUT switches to CUTOUT. Manual stabilizer trim can be used before and after the STAB TRIM CUTOUT switches are moved to CUTOUT." Note that the flight data recorder showed that both crews had moved the trim back to normal with the trim switches, and neither thought to then turn it off.