8 ms·

GOL Airlines to Resume 737 Max Flights on Wednesday

43 points by Rooster61 6y ago

greesil 6y ago
Can anyone who is following this closely provide a good link to a summary of what has actually been fixed?
- garmaine 6y ago
  The manual.
- dudus 6y ago
  Read in passing that the system does not activate multiple times in sequence, and there's an extra sensor input for the pitch (previously it was a single one). Besides the manual being more explicit on the correct workaround. Don't have a source though.
- kayfox 6y ago
  The following: * Changes to the trim system electrical wiring to prevent possible shorts (none have been reported so far). * Changes to the flight laws in the computers to limit MCAS activation authority (how far it moves), limit activation to a single activation, require agreement between AoA sensors and other fixes. * Changes to the manual to outline MCAS system, interaction with other automatic trim systems, normal and non-normal (emergency) procedures. * Changes to baseline training to include more trim system troubleshooting, MCAS system theory and troubleshooting, AoA sensor indications, etc. * Changes in advanced training program recommendations for airlines. There's about 900 individual changes from this, a number of which don't have anything to do with MCAS but were recommended while examining literally every aspect of the aircraft. So the above list is quite incomplete. https://www.federalregister.gov/documents/2020/11/20/2020-25844/airworthiness-directives-the-boeing-company-airplanes https://www.federalregister.gov/documents/2020/11/20/2020-25...
  - greesil 6y ago
    Thank you.
- linuxftw 6y ago
  Nothing was fixed. MCAS simply disables itself if it hits any number of problems. The FAA and the nor the NTSB released any data or appeared to inquire if operating the MAX without the MCAS enabled is safe. They made vague statements like "MCAS only operates in rare flight conditions" without any quantification of "rare." We don't know if a single plane has successfully taken off or landed with MCAS disabled. The real problem that was never addressed is the FAA's complete lack of competence when it comes to certifying the safeness of flight control systems. The same incompetent group of people that approved the planes in the first place are still in charge.
  - tzs 6y ago
    > We don't know if a single plane has successfully taken off or landed with MCAS disabled. Almost all of them have. MCAS is only enabled when flaps are up.
  - kayfox 6y ago
    Its not legal for the MAX to be flown without MCAS. It corrects a control force issue that must be corrected for it to obtain an airworthiness certificate. Cite: FARs §25.173, §25.175.
    - linuxftw 6y ago
      "Force control issue" is Boeing-speak for "anti-stall." If you're holding the stick back, increase thrust, backwards pressure on stick needed to lift nose reduces, you stall and die. What we don't know is how often MCAS actually operated on flights, so we don't know how necessary this component really is. All we know is that Boeing claims it's 'rare' and the FAA did not challenge them on this statement. Unless you have the data, you're repeating their talking points.
      - kayfox 6y ago
        Engine thrust related nose up forces would be less on the MAX as the engines are closer to the CG and CL. What is being compensated for is the change of the center of lift as the AoA changes because of where the engine nacelle is and how big it is. Also, the data that you are expecting the FAA to report on was not being collected by the FAA. You will also note the FAA did not provide any data on how frequently the TOGO switch is used in the Atlas Air investigation, because just like MCAS it is a system that may be activated on normal flights.
lizhang 6y ago
I'm surprised the 737 max did not rebrand after the issues. Will consumers care, or will they continue to buy the cheapest ticket?
dudus 6y ago
Gol rebranded the 737-MAX to 737-8 not to be confused with 737-800 which is part of the 737-NG percursor to the MAX. Not confusing at all. Arguably this confusion is meant to undermine the consumer choice of aircraft during the purchase. GOL has heavy competition from LATAM, AZUL and AVIANCA on most of their routes, and none of these companies are using the 737-MAX AFAIK.
- HappySweeney 6y ago
  The solution is readily apparent: treat all Boeing aircraft as if they are rebranded 737-MAX. Also, I don't find your second paragraph arguable. The model numbers on these planes are not determined by lottery, or for fun. Their marketing departments agonize over every detail for months; they know exactly what they are doing.
  - dkdk8283 6y ago
    Boeing has made some fantastic planes. Their entire history shouldn’t be marginalized because of events in the past few years.
    - HappySweeney 6y ago
      Their amazing, awe-inspiring history should not be employed to shield management from the consequences of playing fast-and-loose with passenger safety.
    - na85 6y ago
      >Boeing has made some fantastic planes. Their entire history shouldn’t be marginalized because of events in the past few years. Yes it should. This is airworthiness; this stuff has to work. You don't give someone a pass on safety-critical stuff because "they usually do a good job". The company's past processes are irrelevant because it's their current corpus of airworthiness procedures that affects the continued airworthiness of their products that are still flying today. The company has demonstrated a serious problem and until it has demonstrated sufficient corrective actions taken to correct the problems observed then everything the company touches should be considered suspect. The fact that Boeing also made B-29s 70 years ago means exactly nothing except for PR purposes or to fanboys. Boeing has no doubt made some changes, but I'll reserve judgment as to whether or not those changes are sufficient because I don't work for a Regulator and don't have the complete picture.
deleted 6y ago
[deleted]
Stierlitz 6y ago
Will the pilot be able to override MCAS at take-off or landing? “Summary of the FAA’s Review of the Boeing 737 MAX” https://www.faa.gov/foia/electronic_reading_room/boeing_reading_room/media/737_RTS_Summary.pdf https://www.faa.gov/foia/electronic_reading_room/boeing_read... “The 737 MAX was designed to handle and feel the same to the pilot as the 737 NG. Without the MCAS function, in some small areas of the flight envelope — such as approaching a stall and during higher g-force maneuvering — the new engines contribute to the control column feeling lighter in the 737 MAX than the regulations allow.” The Flight envelope is unstable without MCAS. “MCAS provides signals to move the horizontal stabilizer at elevated angles of attack to compensate for the aerodynamic effects of the 737 MAX’s larger and more forward-located engines, resulting in the required column feel to the pilot.” The plane pitches nose-up under high acceleration.
- jacquesm 6y ago
  > The Flight envelope is unstable without MCAS. You do not understand the use of the word 'stable' in relation to the words 'flight envelope'. 737 Max is stable across all of its flight envelope. The worst you could accuse it of is that at one extreme of the flight envelope it gets close to neutral, but it never is unstable.
- tzs 6y ago
  > Will the pilot be able to override MCAS at take-off or landing? The pre-fix MCAS has not enabled when flaps were down, which covers a large part of takeoff and landing. I think there was also a minimum altitude for it to be enabled. I don't know if any of this changed with the new version.
- kayfox 6y ago
  Heres a graph that circulated that gives you an idea of what the forces are (please note the graph is not an actual graph, but based on the characteristics as described): https://www.eng-tips.com/viewthread.cfm?qid=457125#:~:text=This%20curve%20represents%20a%20pitching%20moment%20curve https://www.eng-tips.com/viewthread.cfm?qid=457125#:~:text=T... Note that the resistance does not start dropping until after the stall. Also note what MCAS does with the forces.
- 6y ago
dyingkneepad 6y ago
Well, at least now I suppose the pilots are all very very aware of the quirks and details about this airplane. I suppose that even in a hypothetical case where the airplanes were not modified at all we would be safer due to all the alertness about the quirky behavior. Does that make sense?
- jlmorton 6y ago
  We still don't have the exact CVR transcript from the Ethiopia Airways crash, but we have a description of it, and it appears the crew followed the runaway stabilizer checklist. They were certainly aware of the Lion Air crash. However, they could not get manual trim control to work. The manual trim operation requires a large amount of strength to operate when the stabilizer is loaded. It might be true that pilots would now be aware that they need to allow the stabilizer to be in an unloaded position before disabling the automatic trim. But that's a big if when the aircraft is only a few thousand feet off the ground. In other words, without any modifications, if MCAS were to erroneously operate during a takeoff, and the pilots had perfect information on what was happening, it still might be difficult to recover from it. They could probably wait for an MCAS cycle to complete, then disable the automatic trim. But there's only about 60 seconds to complete these actions.
  - ApolloFortyNine 6y ago
    The pilots followed the checklist, but then reenabled the system very soon after. They left the engines at full power during the descent, which made it so they couldn't manually adjust the stabilizer (too strong aerodynamic forces). [1] Sorry about the wiki source, Google is only showing articles from the first 2 months after the accident. The lion air flight, the first one, is an example of the checklist working (and a large reason why the frame wasn't grounded after the first crash, there was evidence that it was avoidable from the day before) . [1] https://en.m.wikipedia.org/wiki/Ethiopian_Airlines_Flight_302 https://en.m.wikipedia.org/wiki/Ethiopian_Airlines_Flight_30...
- deleted 6y ago
  [deleted]
dghlsakjg 6y ago
Traditionally, these threads will have a bunch of people that will proclaim that they will never fly in one of these planes. Am I the only one that actually has no problem with flying on Boeing planes and the MAX? The FAA and Boeing were publicly embarrassed on the world stage. They have every incentive to have gotten this right, the future of American commercial aviation basically rides on this outcome. Both organizations have the technical competency to get it done, and the management culture has been thoroughly slapped down. At this point, I just don't think it is possible for real concerns to have been ignored. As to future development, it would be nice to see Boeing become an engineering first organization. As an aside: the plane was never 'aerodynamically unstable' as so many people purport. MCAS was designed to make the stick pressures identical to the old models.
- deleted 6y ago
  [deleted]
- ceejayoz 6y ago
  I agree. I tend to believe it's gonna be the closest vetted plane in some time at this point - including by European regulators, who've less reason to be nice to Boeing.
- quotha 6y ago
  Would you also drive a Lamborghini that had contrived controls to make it as if you were driving a Ford Taurus? If so, why?
  - ceejayoz 6y ago
    To avoid crashing it as a brand-new owner who's never driven one before? https://www.youtube.com/watch?v=wHs6uGhj41M https://www.youtube.com/watch?v=wHs6uGhj41M Cars already have this sort of thing - anti-lock brakes, traction control, differential braking, etc. All the computer working to make it easier for the driver.
    - quotha 6y ago
      Yes, but you can’t be saying it’s no different from driving a Taurus?!
rsync 6y ago
I can spend a month diving down the rabbit-hole of avionics and flight systems and crash reports and tower transcripts and attempt to make myself an armchair expert on the safety of the 737MAX and then attempt to make a determination of safety for myself and my family. Or I can take a shortcut and see press coverage of the Boeing CEO and BoD and their extended families take a few flights in and out of tricky airports. It's ski season anyway - won't all the grandchildren like a nice flight into ASE ?

43 points by Rooster61 6y ago

greesil 6y ago

Can anyone who is following this closely provide a good link to a summary of what has actually been fixed?

garmaine 6y ago
The manual.
dudus 6y ago
Read in passing that the system does not activate multiple times in sequence, and there's an extra sensor input for the pitch (previously it was a single one). Besides the manual being more explicit on the correct workaround. Don't have a source though.
kayfox 6y ago
The following: * Changes to the trim system electrical wiring to prevent possible shorts (none have been reported so far). * Changes to the flight laws in the computers to limit MCAS activation authority (how far it moves), limit activation to a single activation, require agreement between AoA sensors and other fixes. * Changes to the manual to outline MCAS system, interaction with other automatic trim systems, normal and non-normal (emergency) procedures. * Changes to baseline training to include more trim system troubleshooting, MCAS system theory and troubleshooting, AoA sensor indications, etc. * Changes in advanced training program recommendations for airlines. There's about 900 individual changes from this, a number of which don't have anything to do with MCAS but were recommended while examining literally every aspect of the aircraft. So the above list is quite incomplete. https://www.federalregister.gov/documents/2020/11/20/2020-25844/airworthiness-directives-the-boeing-company-airplanes https://www.federalregister.gov/documents/2020/11/20/2020-25...
- greesil 6y ago
  Thank you.
linuxftw 6y ago
Nothing was fixed. MCAS simply disables itself if it hits any number of problems. The FAA and the nor the NTSB released any data or appeared to inquire if operating the MAX without the MCAS enabled is safe. They made vague statements like "MCAS only operates in rare flight conditions" without any quantification of "rare." We don't know if a single plane has successfully taken off or landed with MCAS disabled. The real problem that was never addressed is the FAA's complete lack of competence when it comes to certifying the safeness of flight control systems. The same incompetent group of people that approved the planes in the first place are still in charge.
- tzs 6y ago
  > We don't know if a single plane has successfully taken off or landed with MCAS disabled. Almost all of them have. MCAS is only enabled when flaps are up.
- kayfox 6y ago
  Its not legal for the MAX to be flown without MCAS. It corrects a control force issue that must be corrected for it to obtain an airworthiness certificate. Cite: FARs §25.173, §25.175.
  - linuxftw 6y ago
    "Force control issue" is Boeing-speak for "anti-stall." If you're holding the stick back, increase thrust, backwards pressure on stick needed to lift nose reduces, you stall and die. What we don't know is how often MCAS actually operated on flights, so we don't know how necessary this component really is. All we know is that Boeing claims it's 'rare' and the FAA did not challenge them on this statement. Unless you have the data, you're repeating their talking points.
    - kayfox 6y ago
      Engine thrust related nose up forces would be less on the MAX as the engines are closer to the CG and CL. What is being compensated for is the change of the center of lift as the AoA changes because of where the engine nacelle is and how big it is. Also, the data that you are expecting the FAA to report on was not being collected by the FAA. You will also note the FAA did not provide any data on how frequently the TOGO switch is used in the Atlas Air investigation, because just like MCAS it is a system that may be activated on normal flights.

lizhang 6y ago

I'm surprised the 737 max did not rebrand after the issues. Will consumers care, or will they continue to buy the cheapest ticket?

dudus 6y ago

Gol rebranded the 737-MAX to 737-8 not to be confused with 737-800 which is part of the 737-NG percursor to the MAX. Not confusing at all. Arguably this confusion is meant to undermine the consumer choice of aircraft during the purchase. GOL has heavy competition from LATAM, AZUL and AVIANCA on most of their routes, and none of these companies are using the 737-MAX AFAIK.

HappySweeney 6y ago
The solution is readily apparent: treat all Boeing aircraft as if they are rebranded 737-MAX. Also, I don't find your second paragraph arguable. The model numbers on these planes are not determined by lottery, or for fun. Their marketing departments agonize over every detail for months; they know exactly what they are doing.
- dkdk8283 6y ago
  Boeing has made some fantastic planes. Their entire history shouldn’t be marginalized because of events in the past few years.
  - HappySweeney 6y ago
    Their amazing, awe-inspiring history should not be employed to shield management from the consequences of playing fast-and-loose with passenger safety.
  - na85 6y ago
    >Boeing has made some fantastic planes. Their entire history shouldn’t be marginalized because of events in the past few years. Yes it should. This is airworthiness; this stuff has to work. You don't give someone a pass on safety-critical stuff because "they usually do a good job". The company's past processes are irrelevant because it's their current corpus of airworthiness procedures that affects the continued airworthiness of their products that are still flying today. The company has demonstrated a serious problem and until it has demonstrated sufficient corrective actions taken to correct the problems observed then everything the company touches should be considered suspect. The fact that Boeing also made B-29s 70 years ago means exactly nothing except for PR purposes or to fanboys. Boeing has no doubt made some changes, but I'll reserve judgment as to whether or not those changes are sufficient because I don't work for a Regulator and don't have the complete picture.

deleted 6y ago

[deleted]

Stierlitz 6y ago

Will the pilot be able to override MCAS at take-off or landing? “Summary of the FAA’s Review of the Boeing 737 MAX” https://www.faa.gov/foia/electronic_reading_room/boeing_reading_room/media/737_RTS_Summary.pdf https://www.faa.gov/foia/electronic_reading_room/boeing_read... “The 737 MAX was designed to handle and feel the same to the pilot as the 737 NG. Without the MCAS function, in some small areas of the flight envelope — such as approaching a stall and during higher g-force maneuvering — the new engines contribute to the control column feeling lighter in the 737 MAX than the regulations allow.” The Flight envelope is unstable without MCAS. “MCAS provides signals to move the horizontal stabilizer at elevated angles of attack to compensate for the aerodynamic effects of the 737 MAX’s larger and more forward-located engines, resulting in the required column feel to the pilot.” The plane pitches nose-up under high acceleration.

jacquesm 6y ago
> The Flight envelope is unstable without MCAS. You do not understand the use of the word 'stable' in relation to the words 'flight envelope'. 737 Max is stable across all of its flight envelope. The worst you could accuse it of is that at one extreme of the flight envelope it gets close to neutral, but it never is unstable.
tzs 6y ago
> Will the pilot be able to override MCAS at take-off or landing? The pre-fix MCAS has not enabled when flaps were down, which covers a large part of takeoff and landing. I think there was also a minimum altitude for it to be enabled. I don't know if any of this changed with the new version.
kayfox 6y ago
Heres a graph that circulated that gives you an idea of what the forces are (please note the graph is not an actual graph, but based on the characteristics as described): https://www.eng-tips.com/viewthread.cfm?qid=457125#:~:text=This%20curve%20represents%20a%20pitching%20moment%20curve https://www.eng-tips.com/viewthread.cfm?qid=457125#:~:text=T... Note that the resistance does not start dropping until after the stall. Also note what MCAS does with the forces.
6y ago

dyingkneepad 6y ago

Well, at least now I suppose the pilots are all very very aware of the quirks and details about this airplane. I suppose that even in a hypothetical case where the airplanes were not modified at all we would be safer due to all the alertness about the quirky behavior. Does that make sense?

jlmorton 6y ago
We still don't have the exact CVR transcript from the Ethiopia Airways crash, but we have a description of it, and it appears the crew followed the runaway stabilizer checklist. They were certainly aware of the Lion Air crash. However, they could not get manual trim control to work. The manual trim operation requires a large amount of strength to operate when the stabilizer is loaded. It might be true that pilots would now be aware that they need to allow the stabilizer to be in an unloaded position before disabling the automatic trim. But that's a big if when the aircraft is only a few thousand feet off the ground. In other words, without any modifications, if MCAS were to erroneously operate during a takeoff, and the pilots had perfect information on what was happening, it still might be difficult to recover from it. They could probably wait for an MCAS cycle to complete, then disable the automatic trim. But there's only about 60 seconds to complete these actions.
- ApolloFortyNine 6y ago
  The pilots followed the checklist, but then reenabled the system very soon after. They left the engines at full power during the descent, which made it so they couldn't manually adjust the stabilizer (too strong aerodynamic forces). [1] Sorry about the wiki source, Google is only showing articles from the first 2 months after the accident. The lion air flight, the first one, is an example of the checklist working (and a large reason why the frame wasn't grounded after the first crash, there was evidence that it was avoidable from the day before) . [1] https://en.m.wikipedia.org/wiki/Ethiopian_Airlines_Flight_302 https://en.m.wikipedia.org/wiki/Ethiopian_Airlines_Flight_30...
deleted 6y ago
[deleted]

dghlsakjg 6y ago

Traditionally, these threads will have a bunch of people that will proclaim that they will never fly in one of these planes. Am I the only one that actually has no problem with flying on Boeing planes and the MAX? The FAA and Boeing were publicly embarrassed on the world stage. They have every incentive to have gotten this right, the future of American commercial aviation basically rides on this outcome. Both organizations have the technical competency to get it done, and the management culture has been thoroughly slapped down. At this point, I just don't think it is possible for real concerns to have been ignored. As to future development, it would be nice to see Boeing become an engineering first organization. As an aside: the plane was never 'aerodynamically unstable' as so many people purport. MCAS was designed to make the stick pressures identical to the old models.

deleted 6y ago
[deleted]
ceejayoz 6y ago
I agree. I tend to believe it's gonna be the closest vetted plane in some time at this point - including by European regulators, who've less reason to be nice to Boeing.
quotha 6y ago
Would you also drive a Lamborghini that had contrived controls to make it as if you were driving a Ford Taurus? If so, why?
- ceejayoz 6y ago
  To avoid crashing it as a brand-new owner who's never driven one before? https://www.youtube.com/watch?v=wHs6uGhj41M https://www.youtube.com/watch?v=wHs6uGhj41M Cars already have this sort of thing - anti-lock brakes, traction control, differential braking, etc. All the computer working to make it easier for the driver.
  - quotha 6y ago
    Yes, but you can’t be saying it’s no different from driving a Taurus?!

rsync 6y ago

I can spend a month diving down the rabbit-hole of avionics and flight systems and crash reports and tower transcripts and attempt to make myself an armchair expert on the safety of the 737MAX and then attempt to make a determination of safety for myself and my family. Or I can take a shortcut and see press coverage of the Boeing CEO and BoD and their extended families take a few flights in and out of tricky airports. It's ski season anyway - won't all the grandchildren like a nice flight into ASE ?