7 ms·

One wonders if the problem of the MAX won't be effectively solved by the Covid-19 triggered recession. With people flying less, it's a pretty good reason to cut

by cletus 7y ago

One wonders if the problem of the MAX won't be effectively solved by the Covid-19 triggered recession. With people flying less, it's a pretty good reason to cut aircraft orders, no? At some point the 737 gravy train was going to end. There's only so long you can maintain the same type rating on a traditional (ie not fly-by-wire) plane where you eventually want to change the handling (as the MAX did by putting on large engines and moving them to compensate). So those who made the decision to go with the MAX rather than the engineer-favoured solution of a complete redesign (because the MAX was going to be ~2 years faster to market and have a captive market of 737 type rating airlines like Southwest) are ruing that decision. Or at least if they hadn't collected huge bonuses for years and were in any way held accountable for a bad call, which sadly they are not.

WalterBright 7y ago
There's nothing wrong with the concept of MCAS. Just it's implementation.
- ljm 7y ago
  Its implementation and the corporate culture that pushed for that. Just as there's nothing wrong with communism, just the Soviet Union's implementation.
  - saagarjha 7y ago
    > Just as there's nothing wrong with communism, just the Soviet Union's implementation. There are many who would make exactly this argument, FWIW.
    - remarkEon 7y ago
      Do they all happen to work for Boeing?
  - aivisol 7y ago
    Have you seen a good implementation yet?
    - rbanffy 7y ago
      In the US: https://en.wikipedia.org/wiki/Twin_Oaks_Community,_Virginia https://en.wikipedia.org/wiki/Twin_Oaks_Community,_Virginia
- kovac 7y ago
  I don't know, I feel like designing a system to prevent a pilot from lifting nose too high up seems to make more sense than a system that actively pushes the nose down after it being lifted. If nothing else, passengers would feel a bit of a discomfort of a sudden nose down movement. Not sure if I missed something in the current design.
  - WalterBright 7y ago
    > I feel like designing a system to prevent a pilot from lifting nose too high up seems to make more sense than a system that actively pushes the nose down after it being lifted Lifting the nose too high can induce a stall, which is very dangerous at low altitude.
    - hef19898 7y ago
      Yep. Also pitching the nose to far down to prevent a stall.
  - numpad0 7y ago
    No it's not about comfort. MAX engine shroud is too far forward to the point it act as canards creating pitch up force at high AoA, in a self reinforcing manner into a belly up into irrecoverable stall. MCAS prevents this by quickly pushing nose down back into airstream. I believe there were discussions earlier on that the FAA requires all civilian airliners to have positive static stability, aka CoL comfortably behind CG so air resistance straightens the attitude without inputs. The opposite of positive static stability is Fly By Wire based 4th-gen onwards jet fighters like F-16, that has CoL only barely aft of CG, that replace aerodynamic stability with electronic PID controllers multiplexed with manual axis inputs for each axes. Those planes could go into a spin over some axis that make sense if at any moment FBW loses control. The fact that MAX needed MCAS, an FBW-like system, to meet FAA standards is itself wrong, and implementation to make it a ghetto nonredundant trim system rather than full FBW is also wrong.
    - WalterBright 7y ago
      > into irrecoverable stall My understanding is it wasn't enough to push it into a stall, the MCAS would just moderate the pitch up slightly so it behaved like the 737. > to meet FAA standards is itself wrong The FAA mandates that all jet airliners since the 707 have a yaw damper to correct for "dutch roll" instability. Augmented controls are normal on jets.
- mihaaly 7y ago
  There's a lot wrong with the existence of the MCAS being a lie on top of a compromise made for other compromises. Being inessential if it was not born on the love of 'not doing it right because it is difficult'. Additionally it was f*d up in the process, yes.
- rbanffy 7y ago
  There is a lot wrong with a plane intended to transport people that requires such a system in order to be safe to fly.
  - adrianN 7y ago
    It requires the system to avoid training pilots.
    - rbanffy 7y ago
      And, yet, it does require proper training after all...
      - WalterBright 7y ago
        Only training to do what they are supposed to do anyway - use the cutoff switches when experiencing runaway trim.
sjwright 7y ago
However it resolves, COVID-19 should not be expected to have significant lasting effects on long distance travel. Worst case scenario is a slight sustained drop due to the global population being cut by as much as two percent. And at the risk of being controversial or callous, the bulk of the deaths are likely to be the elderly. Premature deaths of elderly people wouldn’t have a long term effect on population.
- chaostheory 7y ago
  > And at the risk of being controversial or callous, the bulk of the deaths are likely to be the elderly. Premature deaths of elderly people wouldn’t have a long term effect on population. That’s assuming that the virus doesn’t mutate any further. (Did not downvote you. It isn’t a good subject, but we do need to talk about it)
  - sjwright 7y ago
    I agree, there's a lot of unknowns.
- chillacy 7y ago
  I'm gonna channel Nicholas Taleb and bring up a couple points: 1. Nobody really knows for sure. Predicting the future worst case by comparing it the worst instance from the past in the category is a fallacy (I get the sense you're comparing it to the spanish flu, but consider that the past "worst case" was already surprising to people back then because it was worse than the "past's past") 2. It's not enough to look at pure probabilities, it's also necessary to consider the magnitude of loss for each outcome. For example, Russian Roulette with 100 slots for $100 has a median gain of $100 per round, but you wouldn't want to play that game. 3. I'm not brave enough to put my money on the line but if you're confident you could buy long term options on airline companies and make out like a bandit when travel recovers.
  - onlyrealcuzzo 7y ago
    4. this virus could have similarly severe outbreaks for years.
danielfoster 7y ago
Since airlines are cutting schedules, the virus should theoretically reduce the compensation Boeing has to pay airlines for lost revenue while the plane is grounded.

by cletus 7y ago

WalterBright 7y ago

There's nothing wrong with the concept of MCAS. Just it's implementation.

ljm 7y ago
Its implementation and the corporate culture that pushed for that. Just as there's nothing wrong with communism, just the Soviet Union's implementation.
- saagarjha 7y ago
  > Just as there's nothing wrong with communism, just the Soviet Union's implementation. There are many who would make exactly this argument, FWIW.
  - remarkEon 7y ago
    Do they all happen to work for Boeing?
- aivisol 7y ago
  Have you seen a good implementation yet?
  - rbanffy 7y ago
    In the US: https://en.wikipedia.org/wiki/Twin_Oaks_Community,_Virginia https://en.wikipedia.org/wiki/Twin_Oaks_Community,_Virginia
kovac 7y ago
I don't know, I feel like designing a system to prevent a pilot from lifting nose too high up seems to make more sense than a system that actively pushes the nose down after it being lifted. If nothing else, passengers would feel a bit of a discomfort of a sudden nose down movement. Not sure if I missed something in the current design.
- WalterBright 7y ago
  > I feel like designing a system to prevent a pilot from lifting nose too high up seems to make more sense than a system that actively pushes the nose down after it being lifted Lifting the nose too high can induce a stall, which is very dangerous at low altitude.
  - hef19898 7y ago
    Yep. Also pitching the nose to far down to prevent a stall.
- numpad0 7y ago
  No it's not about comfort. MAX engine shroud is too far forward to the point it act as canards creating pitch up force at high AoA, in a self reinforcing manner into a belly up into irrecoverable stall. MCAS prevents this by quickly pushing nose down back into airstream. I believe there were discussions earlier on that the FAA requires all civilian airliners to have positive static stability, aka CoL comfortably behind CG so air resistance straightens the attitude without inputs. The opposite of positive static stability is Fly By Wire based 4th-gen onwards jet fighters like F-16, that has CoL only barely aft of CG, that replace aerodynamic stability with electronic PID controllers multiplexed with manual axis inputs for each axes. Those planes could go into a spin over some axis that make sense if at any moment FBW loses control. The fact that MAX needed MCAS, an FBW-like system, to meet FAA standards is itself wrong, and implementation to make it a ghetto nonredundant trim system rather than full FBW is also wrong.
  - WalterBright 7y ago
    > into irrecoverable stall My understanding is it wasn't enough to push it into a stall, the MCAS would just moderate the pitch up slightly so it behaved like the 737. > to meet FAA standards is itself wrong The FAA mandates that all jet airliners since the 707 have a yaw damper to correct for "dutch roll" instability. Augmented controls are normal on jets.
mihaaly 7y ago
There's a lot wrong with the existence of the MCAS being a lie on top of a compromise made for other compromises. Being inessential if it was not born on the love of 'not doing it right because it is difficult'. Additionally it was f*d up in the process, yes.
rbanffy 7y ago
There is a lot wrong with a plane intended to transport people that requires such a system in order to be safe to fly.
- adrianN 7y ago
  It requires the system to avoid training pilots.
  - rbanffy 7y ago
    And, yet, it does require proper training after all...
    - WalterBright 7y ago
      Only training to do what they are supposed to do anyway - use the cutoff switches when experiencing runaway trim.

sjwright 7y ago

However it resolves, COVID-19 should not be expected to have significant lasting effects on long distance travel. Worst case scenario is a slight sustained drop due to the global population being cut by as much as two percent. And at the risk of being controversial or callous, the bulk of the deaths are likely to be the elderly. Premature deaths of elderly people wouldn’t have a long term effect on population.

chaostheory 7y ago
> And at the risk of being controversial or callous, the bulk of the deaths are likely to be the elderly. Premature deaths of elderly people wouldn’t have a long term effect on population. That’s assuming that the virus doesn’t mutate any further. (Did not downvote you. It isn’t a good subject, but we do need to talk about it)
- sjwright 7y ago
  I agree, there's a lot of unknowns.
chillacy 7y ago
I'm gonna channel Nicholas Taleb and bring up a couple points: 1. Nobody really knows for sure. Predicting the future worst case by comparing it the worst instance from the past in the category is a fallacy (I get the sense you're comparing it to the spanish flu, but consider that the past "worst case" was already surprising to people back then because it was worse than the "past's past") 2. It's not enough to look at pure probabilities, it's also necessary to consider the magnitude of loss for each outcome. For example, Russian Roulette with 100 slots for $100 has a median gain of $100 per round, but you wouldn't want to play that game. 3. I'm not brave enough to put my money on the line but if you're confident you could buy long term options on airline companies and make out like a bandit when travel recovers.
- onlyrealcuzzo 7y ago
  4. this virus could have similarly severe outbreaks for years.

danielfoster 7y ago

Since airlines are cutting schedules, the virus should theoretically reduce the compensation Boeing has to pay airlines for lost revenue while the plane is grounded.