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From pilot forums.. Actually Boeing sent out a memo to the pilots of the MAX after Lion Air crash explaining what may have caused it and what to do. Here is ba

From pilot forums.. Actually Boeing sent out a memo to the pilots of the MAX after Lion Air crash explaining what may have caused it and what to do. Here is basically what is happening. Upon climb out the pilot will engage the autopilot with it in NAV mode. At this time flaps are still extended for climb out and the aircraft maintains the climb as indicated on the FMS to the assigned altitude. Once the flaps are fully retracted the MCAS engages. At this point the MCAS looks at several things but one being the Vertical Pitch Indicator to either adjust the trim up or down as needed for climb or possibly level flight if needed at this point. The Vertical Pitch Indicator is reading on some MAX 8's 10-20 degrees higher than what the aircraft actually is pitched at. This engages the MCAS to lower the Trim to level the aircraft as needed. Well at this point the plane over pitches nose down because the Vertical Pitch Indicator is saying the plane is pitched up, which it is not. The pilot then will use the Trim on the yoke to trim up also pull back on the yoke and both the MCAS and the pilot are fighting to keep the plane level. Once the pilot stops with the trim adjustment the MCAS goes to full trim down due to adjust for the 10-20 degree increase in the Vertical PItch Indicator it was getting, which is incorrect. At this point the aircraft is sadly most likely in downward angle and unable to recover from it. Boeing did say in a memo what could be done to help stop this during flight. The pilot's can manually override all autopilot functions including MCAS, either first or at that point put the Flaps extended one notch to disengage the MCAS.

debacle 8y ago
Based on what I'm reading, it sounds like a massive liability is on their hands.
- adventured 8y ago
  You're being downvoted, however that is correct. Norwegian Air was the first out of the gate with compensation demands on Boeing.[1] They've recently been in a perilous financial condition, so I'm sure this situation is hurting them more than some.[2] Boeing or their insurer/s will eat a large payout to victims and I'd expect a bunch of airlines to receive some manner of compensation for the mass groundings. They can afford it. $9.5 billion in cash and $11.8 billion in operating income the last four quarters. It's really the reputation damage that hurts a lot more than the direct liability. That damage can last a decade or more and spur long-term erosion (lost sales also obviously hit the service business, which Boeing has worked to expand). They've seen their market value go from ~$80 billion to a recent high of ~$250 billion over just 30 months. That puts them among the elite global corporate giants in valuation. That's based on the way they've been outperforming Airbus the last few years and the improvements in their business that took profitability from $5b to $10b+ per year. Especially with China's state-made 737 competitor inbound, now is a very bad time to be screwing up in that segment. China would love nothing more than to use an opportunity like this to replace Boeing and launch their competing Comac C919 into the market (set to go on sale soon).[3] China can effectively throw a state switch and force all domestic airlines to buy the C919 when it becomes available; the mess with the 737 just makes it that much easier to justify. [1] https://www.marketwatch.com/story/norwegian-air-expects-compensation-from-boeing-for-grounded-737-max-planes--wsj-2019-03-13 https://www.marketwatch.com/story/norwegian-air-expects-comp... [2] https://simpleflying.com/norwegian-air-facing-collapse/ https://simpleflying.com/norwegian-air-facing-collapse/ [3] https://www.foxbusiness.com/features/chinas-boeing-737-max-competitor-is-about-to-be-sold https://www.foxbusiness.com/features/chinas-boeing-737-max-c...
  - inferiorhuman 8y ago
    The C919 has been almost ready for a real long time now. Comac can't even get their license built DC-9 up and running. As of last year I think there were five flying a total average of around one flight segment daily. The C919 is an entirely new design intended to have more domestic Chinese content — fat chance it'll be in production real soon now, even less of a chance it becomes a serious contender. Meanwhile the Russians, who have significantly more experience with airliners, released the SSJ-100 to fairly positive reviews. Unfortunately the after sales support was trash and airlines struggled to keep it flying. Selling a competitive airplane is far more than just the plane itself. There's no way Airbus or Boeing see Comac as a threat. The real threat was Bombardier. Their C-series was an extremely competitive offering and Bombardier has the support infrastructure in place to sell it. Both Swiss and airBaltic seem to love it. Of course, Airbus bought a majority stake in the program.
- c3534l 8y ago
  There's always a massive lawsuit when it comes to airplanes. Any crash, ever, they're gonna have to pay out. So that's the safest bet you can make.
bshipp 8y ago
The manufacturer is telling pilots to extend flaps to disengage MCAS? How is there not a tactile illuminated button in all those 3,000 knobs and switches that the pilot can simply flip to disengage that system? This is just getting weirder and weirder.
- danielvf 8y ago
  That seems quite wrong - maybe got garbled somewhere. Boeing’s official instructions to to all operators after the Lion air crash was to follow existing stabilizer runaway procedures by flipping two switches in the center of the aircraft to disable electronic control of the stabilizer. (You can see a video of this procedure from a few years ago: https://www.youtube.com/watch?v=3pPRuFHR1co&t=154 https://www.youtube.com/watch?v=3pPRuFHR1co&t=154)
  - bshipp 8y ago
    Thanks, that makes much more sense. Maybe they figure it's faster in an emergency to simply pop out the flaps one notch instead of the pilot attempting to find a button which they rarely press. Although, truth be told, I imagine every 737 pilot is keenly aware of that button's location now...
    - matt-attack 8y ago
      I would have thought that was true after the first crash. I'm honestly baffled how it could happen again. If I was aware of this issue from the Lion Air crash, wouldn't every pilot in the world know about it? I mean, if a plane crashes, doesn't every pilot in the world inquire about what caused it? I wouldn't think that would escape a single pilot. Or do I have it wrong? Do they not perceive crashes the same way the general public does?
      - londons_explore 8y ago
        Investigations tend to keep things hush till they have final conclusions, and everyone involved is scared of lawsuits so doesn't want to talk about problems or workarounds on-record. Talking about a workaround or distributing a fix before it's vetted by all the right people and procedures could also be legally risky if the workaround causes other issues. That tends to mean a lot of issues re-occur multiple times before they're resolved.
inferiorhuman 8y ago
I thought MCAS was only active when autopilot is disengaged?
D_Alex 8y ago
Furthermore, it seems that the MCAS acts by moving the entire horizontal stabiliser... whereas the yoke moves the elevators only. This means the MCAS will always "win" in a metaphorical tug-of-war between the two controls. However, the incident of B737 diving into the ground has been observed before, eg: https://en.wikipedia.org/wiki/Flydubai_Flight_981 https://en.wikipedia.org/wiki/Flydubai_Flight_981 and https://en.wikipedia.org/wiki/Tatarstan_Airlines_Flight_363 https://en.wikipedia.org/wiki/Tatarstan_Airlines_Flight_363 , on aircraft not equipped with MCAS. In those cases a possibility of a mechanical malfunction of elevator controls has been raised (but not confirmed) as a possible cause of the crashes.
rebuilder 8y ago
Huh, the pitch indicator is known to be off by a huge margin on some planes and the problem is not fixed?
- Pristina 8y ago
  The problem is fixed by extending the flap one notch to turn off the MCAS. no big deal.
  - yakshaving_jgt 8y ago
    I'm sure no offence was intended, but I'd be quite upset if I heard an engineer say a fix is "no big deal" if I were grieving a lost family member.
    - codebolt 8y ago
      Pretty sure that was sarcasm. Boeing is basically saying, there is an automated system that causes planes to crash, and to turn it off you need to perform some completely unintuitive sequence of actions. These planes should not be allowed to fly.
  - tails4e 8y ago
    That's not a fix it's a workaround. The pitch being off is the problem. Turning off mcas solves it but it does no4 fix mcas
    - breatheoften 8y ago
      I’ve been trying to understand how the vertical pitch measurement is supposed to be suitable for use as part of the MCAS decision process at all. Seems to me wind shear and other atmospheric effects are going to make an airspeed based measurement of angle of attack _always_ subject to condition dependent measurement error. The fact that the pilot is assumed to have a more navigationally useful estimate for angle of attack (in that they are able to know when the angle of attack measurement from the sensor is wrong) makes me think there is something fundamentally flawed about the way this quantity is being estimated by the existing sensor — the modality of measurement might not be an appropriate way to control this flight process if atmospheric effects can bias the measurement in a way that can be calibrated by pilot knowledge but with these corrections not reintroduced into the flight process ...
320rider 8y ago
All correct ! but NO time to execute all this good advice at 1100 ft AGL !! look at crash site terrain hight ! jeez
320rider 8y ago
No time to act as discribed at 1100 ft AGL (see crash site terrain hight) and another one: NO MCAS if flaps, if autopilot, etc...any co-relation between MCAS and radio altitude and/or GPWS ? So MCAS can act even below 1000 ft AGL ? well done boeing !

debacle 8y ago

Based on what I'm reading, it sounds like a massive liability is on their hands.

adventured 8y ago
You're being downvoted, however that is correct. Norwegian Air was the first out of the gate with compensation demands on Boeing.[1] They've recently been in a perilous financial condition, so I'm sure this situation is hurting them more than some.[2] Boeing or their insurer/s will eat a large payout to victims and I'd expect a bunch of airlines to receive some manner of compensation for the mass groundings. They can afford it. $9.5 billion in cash and $11.8 billion in operating income the last four quarters. It's really the reputation damage that hurts a lot more than the direct liability. That damage can last a decade or more and spur long-term erosion (lost sales also obviously hit the service business, which Boeing has worked to expand). They've seen their market value go from ~$80 billion to a recent high of ~$250 billion over just 30 months. That puts them among the elite global corporate giants in valuation. That's based on the way they've been outperforming Airbus the last few years and the improvements in their business that took profitability from $5b to $10b+ per year. Especially with China's state-made 737 competitor inbound, now is a very bad time to be screwing up in that segment. China would love nothing more than to use an opportunity like this to replace Boeing and launch their competing Comac C919 into the market (set to go on sale soon).[3] China can effectively throw a state switch and force all domestic airlines to buy the C919 when it becomes available; the mess with the 737 just makes it that much easier to justify. [1] https://www.marketwatch.com/story/norwegian-air-expects-compensation-from-boeing-for-grounded-737-max-planes--wsj-2019-03-13 https://www.marketwatch.com/story/norwegian-air-expects-comp... [2] https://simpleflying.com/norwegian-air-facing-collapse/ https://simpleflying.com/norwegian-air-facing-collapse/ [3] https://www.foxbusiness.com/features/chinas-boeing-737-max-competitor-is-about-to-be-sold https://www.foxbusiness.com/features/chinas-boeing-737-max-c...
- inferiorhuman 8y ago
  The C919 has been almost ready for a real long time now. Comac can't even get their license built DC-9 up and running. As of last year I think there were five flying a total average of around one flight segment daily. The C919 is an entirely new design intended to have more domestic Chinese content — fat chance it'll be in production real soon now, even less of a chance it becomes a serious contender. Meanwhile the Russians, who have significantly more experience with airliners, released the SSJ-100 to fairly positive reviews. Unfortunately the after sales support was trash and airlines struggled to keep it flying. Selling a competitive airplane is far more than just the plane itself. There's no way Airbus or Boeing see Comac as a threat. The real threat was Bombardier. Their C-series was an extremely competitive offering and Bombardier has the support infrastructure in place to sell it. Both Swiss and airBaltic seem to love it. Of course, Airbus bought a majority stake in the program.
c3534l 8y ago
There's always a massive lawsuit when it comes to airplanes. Any crash, ever, they're gonna have to pay out. So that's the safest bet you can make.

bshipp 8y ago

The manufacturer is telling pilots to extend flaps to disengage MCAS? How is there not a tactile illuminated button in all those 3,000 knobs and switches that the pilot can simply flip to disengage that system? This is just getting weirder and weirder.

danielvf 8y ago
That seems quite wrong - maybe got garbled somewhere. Boeing’s official instructions to to all operators after the Lion air crash was to follow existing stabilizer runaway procedures by flipping two switches in the center of the aircraft to disable electronic control of the stabilizer. (You can see a video of this procedure from a few years ago: https://www.youtube.com/watch?v=3pPRuFHR1co&t=154 https://www.youtube.com/watch?v=3pPRuFHR1co&t=154)
- bshipp 8y ago
  Thanks, that makes much more sense. Maybe they figure it's faster in an emergency to simply pop out the flaps one notch instead of the pilot attempting to find a button which they rarely press. Although, truth be told, I imagine every 737 pilot is keenly aware of that button's location now...
  - matt-attack 8y ago
    I would have thought that was true after the first crash. I'm honestly baffled how it could happen again. If I was aware of this issue from the Lion Air crash, wouldn't every pilot in the world know about it? I mean, if a plane crashes, doesn't every pilot in the world inquire about what caused it? I wouldn't think that would escape a single pilot. Or do I have it wrong? Do they not perceive crashes the same way the general public does?
    - londons_explore 8y ago
      Investigations tend to keep things hush till they have final conclusions, and everyone involved is scared of lawsuits so doesn't want to talk about problems or workarounds on-record. Talking about a workaround or distributing a fix before it's vetted by all the right people and procedures could also be legally risky if the workaround causes other issues. That tends to mean a lot of issues re-occur multiple times before they're resolved.

inferiorhuman 8y ago

I thought MCAS was only active when autopilot is disengaged?

D_Alex 8y ago

Furthermore, it seems that the MCAS acts by moving the entire horizontal stabiliser... whereas the yoke moves the elevators only. This means the MCAS will always "win" in a metaphorical tug-of-war between the two controls. However, the incident of B737 diving into the ground has been observed before, eg: https://en.wikipedia.org/wiki/Flydubai_Flight_981 https://en.wikipedia.org/wiki/Flydubai_Flight_981 and https://en.wikipedia.org/wiki/Tatarstan_Airlines_Flight_363 https://en.wikipedia.org/wiki/Tatarstan_Airlines_Flight_363 , on aircraft not equipped with MCAS. In those cases a possibility of a mechanical malfunction of elevator controls has been raised (but not confirmed) as a possible cause of the crashes.

rebuilder 8y ago

Huh, the pitch indicator is known to be off by a huge margin on some planes and the problem is not fixed?

Pristina 8y ago
The problem is fixed by extending the flap one notch to turn off the MCAS. no big deal.
- yakshaving_jgt 8y ago
  I'm sure no offence was intended, but I'd be quite upset if I heard an engineer say a fix is "no big deal" if I were grieving a lost family member.
  - codebolt 8y ago
    Pretty sure that was sarcasm. Boeing is basically saying, there is an automated system that causes planes to crash, and to turn it off you need to perform some completely unintuitive sequence of actions. These planes should not be allowed to fly.
- tails4e 8y ago
  That's not a fix it's a workaround. The pitch being off is the problem. Turning off mcas solves it but it does no4 fix mcas
  - breatheoften 8y ago
    I’ve been trying to understand how the vertical pitch measurement is supposed to be suitable for use as part of the MCAS decision process at all. Seems to me wind shear and other atmospheric effects are going to make an airspeed based measurement of angle of attack _always_ subject to condition dependent measurement error. The fact that the pilot is assumed to have a more navigationally useful estimate for angle of attack (in that they are able to know when the angle of attack measurement from the sensor is wrong) makes me think there is something fundamentally flawed about the way this quantity is being estimated by the existing sensor — the modality of measurement might not be an appropriate way to control this flight process if atmospheric effects can bias the measurement in a way that can be calibrated by pilot knowledge but with these corrections not reintroduced into the flight process ...

320rider 8y ago

All correct ! but NO time to execute all this good advice at 1100 ft AGL !! look at crash site terrain hight ! jeez

320rider 8y ago

No time to act as discribed at 1100 ft AGL (see crash site terrain hight) and another one: NO MCAS if flaps, if autopilot, etc...any co-relation between MCAS and radio altitude and/or GPWS ? So MCAS can act even below 1000 ft AGL ? well done boeing !