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.
* 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.
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.
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.
"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.
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.
>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.
Your belligerent tone is probably what's netting you the downvotes but this portion is more or less true.
The FAA has clearly demonstrated they cannot competently evaluate systems like MCAS, whether because of a lack of technical expertise or because of too little staffpower, or some other institutional reason. I suspect a mix of both; as we saw from the crashes the interplay between MCAS and the rest of the aircraft has subtleties that were obviously not considered.
You would think the FAA would thoroughly test and vet the procedure of 'flying plane without MCAS' because now MCAS will be disabled, possibly intermittently, possibly at unexpected times. Thus, where is the data from existing flights showing just how 'rare' activation really is. It seems like the FAA avoided the question of "is the plane safe without MCAS" entirely.
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.
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.
Their amazing, awe-inspiring history should not be employed to shield management from the consequences of playing fast-and-loose with passenger safety.
>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.
Renaming the aircraft to avoid the reputation is scummy and predictable, but aircraft scheduling being what it is, if your chosen airline flies 737-MAX, and your flight's distance is within the 737-MAX capabilities, there's no way to know if you'll be on a 737-MAX until boarding. The 737 in general is very compatible with commercial airports, so there's probably not a lot of scheduldd routes 737-MAX can't service because it's too big.
If you have a preference to avoid this aircraft, you need to book flights on airlines that don't have any, or that are too long for it, or be prepared to abandon your ticket at boarding.
"Boeing appears to have started quietly dropping the “Max” from its 737 Max aircraft in the wake of recent air disasters, instead referring to a 737-8.
The new name has hitherto been used only internally at Boeing and emerged when the company put out a statement on Wednesday to announce it had won its first order for the grounded 737 Max aircraft this year. "
“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.
> 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.
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):
> Either pilot can override MCAS commands to control the stabilizer by using the electric stabilizer trim switches on the control wheel. Additionally, flightcrews can set the STAB TRIM CUTOUT switches on the center control stand to CUTOUT to stop and disable MCAS.
So pilots would be able to override MCAS (and they could before, though it was less explicit). They can't routinely override it at take-off or landing because 737 MAX without MCAS is non-compliant and:
> when MCAS and Speed Trim are disabled, SPEED TRIM FAIL is annunciated and a maintenance item is recorded.
e: Also, there were changes for when/how MCAS is in effect
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?
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.
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) .
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.
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.
I'm saying I can see the potential utility of such a feature.
I think the decision to use MCAS to avoid retraining pilots was a bad one in hindsight, but it's just one of many situations where we use computers to assist pilots/drivers with this sort of task.
MCAS is not required. The plane flies just fine without it.
MCAS was added so the minor differences in how it flies could be adjusted away by computer to avoid needing to retrain pilots already certified for the 737-NG.
> Boeing put MCAS on the plane not to make it stable in maneuvers approaching a stall but to make it handle and feel exactly the same as the earlier model 737NG.
> “If MCAS is deactivated, you can still fly the aircraft and it is not unstable,” said Fehrm. “The Max without MCAS is a perfectly flyable aircraft.”
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.
> Its not legal for the MAX to be flown without MCAS.
That's an entirely different claim, though, than this:
> Without it, the max is like a very badly designed fighter jet.
Boeing isn't taking the "get rid of MCAS" approach, they're taking the "fix MCAS" one. If they wanted to get rid of MCAS, though, they'd have to apply for a new cert, without the "737-NG pilots can fly it just fine" piggybacking they did - pilots would have to be trained to the new aircraft type.
If you drive any car in Canada, the US, or the EU built after 2014 then you already have something similar in mandated ESC.
The car will apply uncommanded brake inputs to assist in steering the car in what the car determines to be the intended direction.
Would I drive a 2014 or later model year Lamborghini? Yes, I absolutely would.
I do get your point.
But the whole reason for MCAS was so that it WOULD be identical.
They weren't selling a lambo as a taurus. They were selling a more efficient taurus with more seats and promising that it would drive just like the old one so you didn't have to retrain your drivers.
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.
Reminds me of those who said they'd never ride in a Toyota again after the unintended acceleration catastrophe. It cost them BILLIONS, now people hardly remember it.
Utterly different scenario. Toyota was not a "too-big-to-fail" US defense contractor, and thus there was not a domestic entity allowing Toyota to police itself on engineering practices that should have oversight.
I'm not convinced that relationship has changed that much due to this debacle, so I remain skeptical of Boeing and its products, as well as the FAA to give correct oversight over the long term.
I guarantee that everyone, including you, will have forgotten this completely in 5 years. I would put money on it.
It would be cool if carriers caved into this fear and sold 737 MAX tickets at a discount.
Also, you're forgetting EASA and other countries' regulators. I'm sure they've picked over everything as well. I think they had egg on their face, as they're supposed to act as another foreign check on these designs.
I absolutely will not forget this, if not for the actual tragedy of it, then for the sheer engineering laziness/ineptitude/corruption that occurred here. Boeing is tarnished and will remain so in my book.
>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.
In most of these discussions, "Aerodynamically unstable" is just a layperson's term used when the speaker doesn't realize that stability has a specific quantitative definition in aerodynamics, and is used to generally mean "an airplane that isn't safe". 99% of HN users have exactly zero idea what they're talking about when it comes to aircraft.
Yeah the discussions about aircraft have really opened me up to how much BS HN generates outside of the "tech" subject.
Many people clearly have no idea what they are talking about, but write statements like it is a hard fact.
Makes me wonder what else I read on here that is clearly false.
> They have every incentive to have gotten this right
I mean, they had this from the beginning. Do they have the technical competency? Did their management get thoroughly slapped down? Building planes is not easy.
I 100% believe they put in a good faith effort to fix their planes. I don't know if I believe that was enough.
I will probably fly on one because its not an especially transparent process to choose plane models, but I would definitely prefer not to.
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 ?
67 comments
[ 2.2 ms ] story [ 115 ms ] threadDon't have a source though.
* 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/2020/11/20/2020-25...
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.
Almost all of them have. MCAS is only enabled when flaps are up.
Cite: FARs §25.173, §25.175.
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.
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.
Your belligerent tone is probably what's netting you the downvotes but this portion is more or less true.
The FAA has clearly demonstrated they cannot competently evaluate systems like MCAS, whether because of a lack of technical expertise or because of too little staffpower, or some other institutional reason. I suspect a mix of both; as we saw from the crashes the interplay between MCAS and the rest of the aircraft has subtleties that were obviously not considered.
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.
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.
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.
Did they? I still see a lot of references to the MAX 8 on their fleet page, notably separate from their 737-800 fleet.
Reference:
https://www.aeroin.net/gol-muda-nome-boeing-737-max-8-para-7...
If you have a preference to avoid this aircraft, you need to book flights on airlines that don't have any, or that are too long for it, or be prepared to abandon your ticket at boarding.
The new name has hitherto been used only internally at Boeing and emerged when the company put out a statement on Wednesday to announce it had won its first order for the grounded 737 Max aircraft this year. "
Source: https://www.theguardian.com/business/2020/aug/20/boeing-737-...
And calling the variants -7/-8/-9 kinda makes sense (MAX 7/MAX 8/MAX 9 are more "official").
“Summary of the FAA’s Review of the Boeing 737 MAX”
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.
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.
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.
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.
So pilots would be able to override MCAS (and they could before, though it was less explicit). They can't routinely override it at take-off or landing because 737 MAX without MCAS is non-compliant and:
> when MCAS and Speed Trim are disabled, SPEED TRIM FAIL is annunciated and a maintenance item is recorded.
e: Also, there were changes for when/how MCAS is in effect
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.
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_30...
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.
If so, why?
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.
I think the decision to use MCAS to avoid retraining pilots was a bad one in hindsight, but it's just one of many situations where we use computers to assist pilots/drivers with this sort of task.
Without it, the max is like a very badly designed fighter jet.
MCAS was added so the minor differences in how it flies could be adjusted away by computer to avoid needing to retrain pilots already certified for the 737-NG.
https://www.chicagotribune.com/business/ct-biz-boeing-737-ma...
> Boeing put MCAS on the plane not to make it stable in maneuvers approaching a stall but to make it handle and feel exactly the same as the earlier model 737NG.
> “If MCAS is deactivated, you can still fly the aircraft and it is not unstable,” said Fehrm. “The Max without MCAS is a perfectly flyable aircraft.”
Cite: FARs §25.173, §25.175.
That's an entirely different claim, though, than this:
> Without it, the max is like a very badly designed fighter jet.
Boeing isn't taking the "get rid of MCAS" approach, they're taking the "fix MCAS" one. If they wanted to get rid of MCAS, though, they'd have to apply for a new cert, without the "737-NG pilots can fly it just fine" piggybacking they did - pilots would have to be trained to the new aircraft type.
The car will apply uncommanded brake inputs to assist in steering the car in what the car determines to be the intended direction.
Would I drive a 2014 or later model year Lamborghini? Yes, I absolutely would.
I do get your point.
But the whole reason for MCAS was so that it WOULD be identical.
They weren't selling a lambo as a taurus. They were selling a more efficient taurus with more seats and promising that it would drive just like the old one so you didn't have to retrain your drivers.
I'm not convinced that relationship has changed that much due to this debacle, so I remain skeptical of Boeing and its products, as well as the FAA to give correct oversight over the long term.
It would be cool if carriers caved into this fear and sold 737 MAX tickets at a discount.
Also, you're forgetting EASA and other countries' regulators. I'm sure they've picked over everything as well. I think they had egg on their face, as they're supposed to act as another foreign check on these designs.
You have a point, but Everyone is a lot of people.
In most of these discussions, "Aerodynamically unstable" is just a layperson's term used when the speaker doesn't realize that stability has a specific quantitative definition in aerodynamics, and is used to generally mean "an airplane that isn't safe". 99% of HN users have exactly zero idea what they're talking about when it comes to aircraft.
Makes me wonder what else I read on here that is clearly false.
I mean, they had this from the beginning. Do they have the technical competency? Did their management get thoroughly slapped down? Building planes is not easy.
I 100% believe they put in a good faith effort to fix their planes. I don't know if I believe that was enough.
I will probably fly on one because its not an especially transparent process to choose plane models, but I would definitely prefer not to.
They had 346 incentives to have gotten it right from the beginning, but that didn't happen.
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 ?