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Aerospace engineer here. This is incorrect. The MAX exhibits different pitch behavior at high angles of attack than the 737NG, which would normally require a di

Aerospace engineer here. This is incorrect. The MAX exhibits different pitch behavior at high angles of attack than the 737NG, which would normally require a different type certificate. MCAS was their attempt to change the handling characteristics of the MAX aircraft so that it was sufficiently similar to previous iterations of the 737. I'm sure the pitch up tendency is worse on the MAX, but I don't believe MCAS was added to enable the re-use of the same type certificate. The handling problems were worse than anticipated as is evidenced by the low-speed activation of MCAS. My guess is that the 737 MAX on its own wouldn't meet the handling requirements. It's been a while since the Ducommun scandal, but more recently Boeing was caught knowingly installing unsafe parts (NG/MAX slat tracks that didn't meet spec) and forging repair documentation for Air Canada. Pardon me if I take any claims that Boeing is spewing with a lump of salt. inadequate pilot training. It's hard to train for something that the manufacturer won't disclose or implement in the sims. It's even harder when the remedy (moving the trim wheels) is physically impossible.

na85 7y ago
>the re-use of the same type certificate. That was the demand from the airlines; that there be no training delta. For that you need to remain within the same type, or at least close enough that they're equivalent. >My guess is that the 737 MAX on its own wouldn't meet the handling requirements. Correct. >It's hard to train for something that the manufacturer won't disclose or implement in the sims. It's even harder when the remedy (moving the trim wheels) is physically impossible. Yes. The training the pilots received on the differences between the MAX and the NG (i.e. no training) was inadequate to prepare them to fly the aircraft safely.
- inferiorhuman 7y ago
  That was the demand from the airlines; that there be no training delta. For that you need to remain within the same type, or at least close enough that they're equivalent. Those are two separate issues. There are currently four generations of 737 on the TC[1] and sim time is required between the different generations. Look at the 777 vs 777X, there are radical changes and yet the 777X is (for now) grandfathered on the 777 TC. A change requiring a new TC (or STC) is an order of magnitude more dramatic. The training mandate drove the poor design of MCAS but wasn't the reason MCAS was implemented. Even with training the MAX would never have met FAA regs without something like MCAS. The list price of the MAX is around $100 million, and Southwest wanted $1 million per aircraft if training were reqiured. If it were simply a matter of more appropriate training Boeing would've already taken the 1% haircut and moved on. American talked a good game about not wanting the MAX at all if training were required, but let's face it they'd probably rather take the training hit than wait in line for an A320 production slot. Instead Boeing shuttered the production line because the problem is simply not that easy to solve. If it were simply a matter of stick force gradient Boeing could've likely just modified the elevator feel computer. Instead Boeing went the route of moving the whole damn stabilizer, a particularly odd choice because the stabilizer moves very slowly -- slower than a reasonable person would want to prevent an impending stall. 1: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/179cdacd213801658625832a006b2e37/$FILE/A16WE_Rev_64.pdf http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeMod...
  - na85 7y ago
    Thanks for the clarification; I don't work for the airlines so I wasn't aware of the sim time requirements.
    - inferiorhuman 7y ago
      Here's the detailed list of differences training requirements: http://fsims.faa.gov/wdocs/fsb/b737_rev_15.pdf http://fsims.faa.gov/wdocs/fsb/b737_rev_15.pdf
  - panarky 7y ago
    All these arguments are about engineering. It's no longer an engineering problem. Now it's a trust problem. Boeing, the FAA, and the airlines have demonstrated that they can't be trusted to make the right decision when passenger safety conflicts with quarterly earnings per share. They'll roll the dice and hope they can fix the problem, as cheaply as possible, before the next catastrophe. So it doesn't matter if they find an engineering fix. The public will never trust that it's really fixed, and re-branding this dud won't fool anybody. The sooner Boeing figures this out, the less money they'll lose.
    - qtplatypus 7y ago
      This is why Boeing never should have been allowed to self certify. Decisions about Matters of safety should have been given to people who didn’t have to weigh it against earnings per share.
phkahler 7y ago
>> The handling problems were worse than anticipated as is evidenced by the low-speed activation of MCAS. I'd say the handling is bad enough to require something like MCAS in order to be safe. If not, they would have just disabled it and ate the cost of training pilots for the new variant. Instead they think it's better (cheaper) to try to fix MCAS while letting planes pile up that will likely require extra training on the new fix anyway. In other words I agree. It probably doesnt fly well without help, as opposed to just flying differently.
rootusrootus 7y ago
> The handling problems were worse than anticipated as is evidenced by the low-speed activation of MCAS Where the heck did you get that from? The MCAS failures were caused by a failure of the AOA sensors, not any kind of handling characteristics.
- inferiorhuman 7y ago
  Where the heck did you get that from? The MCAS failures were caused by a failure of the AOA sensors, not any kind of handling characteristics. MCAS was originally intended to handle high speed, high altitude situations. Flight testing found that there were handling problems at lower speeds and altitudes that MCAS could "fix". So MCAS was given roughly twice the authority it was originally designed with and it was then programmed to activate in lower speed situations as well. The FAA, of course, was kept in the dark. If you're curious go through the Seattle Times articles.
deleted 7y ago
[deleted]

na85 7y ago

>the re-use of the same type certificate. That was the demand from the airlines; that there be no training delta. For that you need to remain within the same type, or at least close enough that they're equivalent. >My guess is that the 737 MAX on its own wouldn't meet the handling requirements. Correct. >It's hard to train for something that the manufacturer won't disclose or implement in the sims. It's even harder when the remedy (moving the trim wheels) is physically impossible. Yes. The training the pilots received on the differences between the MAX and the NG (i.e. no training) was inadequate to prepare them to fly the aircraft safely.

inferiorhuman 7y ago
That was the demand from the airlines; that there be no training delta. For that you need to remain within the same type, or at least close enough that they're equivalent. Those are two separate issues. There are currently four generations of 737 on the TC[1] and sim time is required between the different generations. Look at the 777 vs 777X, there are radical changes and yet the 777X is (for now) grandfathered on the 777 TC. A change requiring a new TC (or STC) is an order of magnitude more dramatic. The training mandate drove the poor design of MCAS but wasn't the reason MCAS was implemented. Even with training the MAX would never have met FAA regs without something like MCAS. The list price of the MAX is around $100 million, and Southwest wanted $1 million per aircraft if training were reqiured. If it were simply a matter of more appropriate training Boeing would've already taken the 1% haircut and moved on. American talked a good game about not wanting the MAX at all if training were required, but let's face it they'd probably rather take the training hit than wait in line for an A320 production slot. Instead Boeing shuttered the production line because the problem is simply not that easy to solve. If it were simply a matter of stick force gradient Boeing could've likely just modified the elevator feel computer. Instead Boeing went the route of moving the whole damn stabilizer, a particularly odd choice because the stabilizer moves very slowly -- slower than a reasonable person would want to prevent an impending stall. 1: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/179cdacd213801658625832a006b2e37/$FILE/A16WE_Rev_64.pdf http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeMod...
- na85 7y ago
  Thanks for the clarification; I don't work for the airlines so I wasn't aware of the sim time requirements.
  - inferiorhuman 7y ago
    Here's the detailed list of differences training requirements: http://fsims.faa.gov/wdocs/fsb/b737_rev_15.pdf http://fsims.faa.gov/wdocs/fsb/b737_rev_15.pdf
- panarky 7y ago
  All these arguments are about engineering. It's no longer an engineering problem. Now it's a trust problem. Boeing, the FAA, and the airlines have demonstrated that they can't be trusted to make the right decision when passenger safety conflicts with quarterly earnings per share. They'll roll the dice and hope they can fix the problem, as cheaply as possible, before the next catastrophe. So it doesn't matter if they find an engineering fix. The public will never trust that it's really fixed, and re-branding this dud won't fool anybody. The sooner Boeing figures this out, the less money they'll lose.
  - qtplatypus 7y ago
    This is why Boeing never should have been allowed to self certify. Decisions about Matters of safety should have been given to people who didn’t have to weigh it against earnings per share.

phkahler 7y ago

>> The handling problems were worse than anticipated as is evidenced by the low-speed activation of MCAS. I'd say the handling is bad enough to require something like MCAS in order to be safe. If not, they would have just disabled it and ate the cost of training pilots for the new variant. Instead they think it's better (cheaper) to try to fix MCAS while letting planes pile up that will likely require extra training on the new fix anyway. In other words I agree. It probably doesnt fly well without help, as opposed to just flying differently.

rootusrootus 7y ago

> The handling problems were worse than anticipated as is evidenced by the low-speed activation of MCAS Where the heck did you get that from? The MCAS failures were caused by a failure of the AOA sensors, not any kind of handling characteristics.

inferiorhuman 7y ago
Where the heck did you get that from? The MCAS failures were caused by a failure of the AOA sensors, not any kind of handling characteristics. MCAS was originally intended to handle high speed, high altitude situations. Flight testing found that there were handling problems at lower speeds and altitudes that MCAS could "fix". So MCAS was given roughly twice the authority it was originally designed with and it was then programmed to activate in lower speed situations as well. The FAA, of course, was kept in the dark. If you're curious go through the Seattle Times articles.

deleted 7y ago

[deleted]