Boeing proposal to avoid 737-MAX wiring shift does not win U.S. support(reuters.com)
reuters.com
Boeing proposal to avoid 737-MAX wiring shift does not win U.S. support
https://www.reuters.com/article/us-boeing-737max/boeing-proposal-to-avoid-max-wiring-shift-does-not-win-u-s-support-idUSKBN20W018
81 comments
Boeing looks more lika a petulant child that got caught cheating on their chores. That then got caught cheating on those same chores enough times in the same day, that their parents needed to get a chair and watch them complete them.
Tangentially, I believe the root cause of all software architecture debates is an argument over who pays what aspect of cost.
Language goals such as expressivity, readability, brevity, composability; and features such as static typing; and patterns such as monoliths and microservices, ship-fast-fix-later, agile and waterfall design, centralized vs distributed; and aphorisms such as DRY and YAGNI - can be evaluated in the framework of shifting cost between original programmer, future maintainer, service provider, service user, or library/module reuser (and one individual may assume all of those roles at different points in the software’s lifecycle!).
Language goals such as expressivity, readability, brevity, composability; and features such as static typing; and patterns such as monoliths and microservices, ship-fast-fix-later, agile and waterfall design, centralized vs distributed; and aphorisms such as DRY and YAGNI - can be evaluated in the framework of shifting cost between original programmer, future maintainer, service provider, service user, or library/module reuser (and one individual may assume all of those roles at different points in the software’s lifecycle!).
Well yea, I guess the underlying trueism is that "its turtles all the way down" in all things. We like to act like over-arching things (safety) weigh higher, and so we speak like the decision to go for safety isn't an economic decision, but in truth, it always is.
Free software has costs, so its not like FOSS is outside this loop either.
Once you start modelling everything in cost/benefit terms, it all gets a bit odd. I think "because I want to" looses out.
But in Aircraft design, and regulatory oversight, I think we might want to shift the knobs on the control box a bit.
Free software has costs, so its not like FOSS is outside this loop either.
Once you start modelling everything in cost/benefit terms, it all gets a bit odd. I think "because I want to" looses out.
But in Aircraft design, and regulatory oversight, I think we might want to shift the knobs on the control box a bit.
Nice insight!
While I agree there are some very hard trade offs that we have to make along all of those axes, I do also think there times when people aren't being ... thoughtful and you end up with situations that are far off the pareto frontier.
While I agree there are some very hard trade offs that we have to make along all of those axes, I do also think there times when people aren't being ... thoughtful and you end up with situations that are far off the pareto frontier.
> There is no other reason we are here, than money.
Various articles indicate that competitive pressure and trying to speed up development of a competitive alternative was also a cause for this. A new airplane would've required more work to get it certified. Making the changes under an existing type certification saves a lot of time.
Possibly a more engineering focussed company would've developed an alternative much earlier than when Boeing finally woke up.
Various articles indicate that competitive pressure and trying to speed up development of a competitive alternative was also a cause for this. A new airplane would've required more work to get it certified. Making the changes under an existing type certification saves a lot of time.
Possibly a more engineering focussed company would've developed an alternative much earlier than when Boeing finally woke up.
Not an aircraft safety expert but I am curious if shifting the wires may not introduce more potential issues in existing planes, as the existing risk factor seems to be proven low (i.e. they are not requiring all 737-NG airframes to have the work)
I would imagine there is a non-trivial risk of a worker introducing a higher risk factor (drilling a little too far, creating metal shavings, putting too much weight on a support).
The rules were made for a reason, and Boeing should follow them. However I wonder if it would be safer to simply fine Boeing a similar cost to what the rectification would cost and grandfather it in for existing airframes.
I am just glad there are people more qualified to make this decision.
I would imagine there is a non-trivial risk of a worker introducing a higher risk factor (drilling a little too far, creating metal shavings, putting too much weight on a support).
The rules were made for a reason, and Boeing should follow them. However I wonder if it would be safer to simply fine Boeing a similar cost to what the rectification would cost and grandfather it in for existing airframes.
I am just glad there are people more qualified to make this decision.
Boeing wants to have a quick and cheap fix (no fix) and get a pass on international aviation norms based on the argument it's not "too unsafe" and that fixing it would risk making the 737 MAX fleet non-flightworthy.
Well... It's not like it's flightworthy right now. If Boeing can't offer a fix that makes the plane flightworthy, then the airplanes should be scrapped. Remember we only are experiencing this because Boeing wanted a plane of the same type rating as the 737 NG and opted for that instead of a new design (that would be in accordance to all current safety norms, unlike the MAX) because it'd increase their profit.
Two planes fell from the sky, killing everyone on board, for no other reason than Boeing wanting to increase its profits.
Well... It's not like it's flightworthy right now. If Boeing can't offer a fix that makes the plane flightworthy, then the airplanes should be scrapped. Remember we only are experiencing this because Boeing wanted a plane of the same type rating as the 737 NG and opted for that instead of a new design (that would be in accordance to all current safety norms, unlike the MAX) because it'd increase their profit.
Two planes fell from the sky, killing everyone on board, for no other reason than Boeing wanting to increase its profits.
I thought the planes would be fine if Boeing just dropped the idea that they could be flown by pilots only trained to fly the 737.
Is the plane not safe to fly in general AND it needs pilots trained to fly it specifically?
Is the plane not safe to fly in general AND it needs pilots trained to fly it specifically?
IIRC, on a high AoA the lift generated by the larger engines moves the center of lift ahead of the center of gravity, making the plane unstable. This is what MCAS was arguably designed to prevent, forcing the plane behave like a 737 with smaller engines.
Without MCAS, this would be a crappy experience for the pilots, but, with proper training, they'd be able to fly it just like you and me can safely drive cars like a Reliant Robin (just never think about hitting the brakes in a curve). If you feel the plane wanting to point up a bit too enthusiastically, you can push the stick forward (or adjust the trim) and make it more cooperative.
It just turns out that, with MCAS, little training, and a defective AoA sensor, the experience was lethally crappy.
Without MCAS, this would be a crappy experience for the pilots, but, with proper training, they'd be able to fly it just like you and me can safely drive cars like a Reliant Robin (just never think about hitting the brakes in a curve). If you feel the plane wanting to point up a bit too enthusiastically, you can push the stick forward (or adjust the trim) and make it more cooperative.
It just turns out that, with MCAS, little training, and a defective AoA sensor, the experience was lethally crappy.
>lift generated by the larger engines moves the center of lift ahead of the center of gravity
Do you have a reliable source for the center of lift behind CoG shift? I've not seen that claim before.
Do you have a reliable source for the center of lift behind CoG shift? I've not seen that claim before.
This doesn't mention CoG, but it mentions "dynamic instability":
https://spectrum.ieee.org/aerospace/aviation/how-the-boeing-...
In the 737 Max, the engine nacelles themselves can, at high angles of attack, work as a wing and produce lift. And the lift they produce is well ahead of the wing’s center of lift, meaning the nacelles will cause the 737 Max at a high angle of attack to go to a higher angle of attack. This is aerodynamic malpractice of the worst kind.
https://spectrum.ieee.org/aerospace/aviation/how-the-boeing-...
In the 737 Max, the engine nacelles themselves can, at high angles of attack, work as a wing and produce lift. And the lift they produce is well ahead of the wing’s center of lift, meaning the nacelles will cause the 737 Max at a high angle of attack to go to a higher angle of attack. This is aerodynamic malpractice of the worst kind.
Yes, that doesn't claim that the center of lift shifts ahead of the CoG. Nor is it a reliable source.
Not op and on mobile, but I have seen the CoG shift mentioned in threads and articles before on this topic.
Would love a source to confirm my memory though.
Would love a source to confirm my memory though.
> Without MCAS, this would be a crappy experience for the pilots, but, with proper training, they'd be able to fly it just like you and me can safely drive cars like a Reliant Robin (just never think about hitting the brakes in a curve). If you feel the plane wanting to point up a bit too enthusiastically, you can push the stick forward (or adjust the trim) and make it more cooperative.
That's the worst part of this, the plane is perfectly flyable without MCAS but they applied it anyways because it would have required recertifying pilots because that difference is enough that it might have required a new type certificate for pilots to fly. So all this trouble and the deaths are because Boeing couldn't make an appealing aircraft with the old 737 body and handling so they took a shortcut to make few 100M more.
That's the worst part of this, the plane is perfectly flyable without MCAS but they applied it anyways because it would have required recertifying pilots because that difference is enough that it might have required a new type certificate for pilots to fly. So all this trouble and the deaths are because Boeing couldn't make an appealing aircraft with the old 737 body and handling so they took a shortcut to make few 100M more.
That's just the with it feeling wrong near stall at high angle-of-attacks.
Theoretically yes, you can train pilots to deal with it. Hell, it would have been safer to just ignore the issue and not train pilots than the clusterfuck of the original MCAS implementation.
But it's not that it doesn't just feel wrong compared to the 737-NG. It feels wrong compared to every single certified aircraft.
The FAA has strict rules on how all aircraft must feel when approaching stall. You can't certify an aircraft without meeting this feel requirement. So the 737-MAX simply can't be certified without MCAS or some other fix.
Theoretically yes, you can train pilots to deal with it. Hell, it would have been safer to just ignore the issue and not train pilots than the clusterfuck of the original MCAS implementation.
But it's not that it doesn't just feel wrong compared to the 737-NG. It feels wrong compared to every single certified aircraft.
The FAA has strict rules on how all aircraft must feel when approaching stall. You can't certify an aircraft without meeting this feel requirement. So the 737-MAX simply can't be certified without MCAS or some other fix.
There are sort of 3 classes of issues here.
a) The initial issue found, the MCAS system, which might be fixable by what you suggest. Except that would break the regulatory workaround for b.
b) A bunch of issues where the plane violates modern standards but has been allowed by abusing grandfather clauses.
c) New issues that have been found since the discovery of issue a that are not grandfathered.
The wiring issue being discussed is category c.
a) The initial issue found, the MCAS system, which might be fixable by what you suggest. Except that would break the regulatory workaround for b.
b) A bunch of issues where the plane violates modern standards but has been allowed by abusing grandfather clauses.
c) New issues that have been found since the discovery of issue a that are not grandfathered.
The wiring issue being discussed is category c.
The actual problem is Boeing made more changes from the 737 base and the checks for this changes were nod done properly because FAA didn't do it's job. Now if FAA and other international agencies check everything from scratch you will find all this hidden problems.
Now imagine you are hired to check the plane systems, would you sign on subsystem X because it worked fine in the old 737 or use your brain and experience andcx flag all potential issues you see.
Now imagine you are hired to check the plane systems, would you sign on subsystem X because it worked fine in the old 737 or use your brain and experience andcx flag all potential issues you see.
I am also a non-expert, and am sympathetic to your argument, but I don’t think there’s any reason to believe that whatever fix is proposed wouldn’t account for the type of risks you are concerned about. All of the risks/concerns you mention would be relevant to any sort of mechanical work on an aircraft, and that is a field of engineering that on the whole has an impeccable record of safety and rigor. Again, not an expert, but from what I understand the issues with the 737 max were software/design related.
And (lack of) proper pilot training
Mostly agree, however I think Boeing should be required to engineer an approved and deemed safe remedy by a panel of experts comprised of international regulatory engineering staff deemed to be experts in this field.
The cost would be the greater of the approved solution or the envisioned cost of correctly re-working existing airlines. (The cost savings might come from a factor of cost not considered here, Boeing's liability to airlines for downtime of units or inability to sell new planes.)
The cost would be the greater of the approved solution or the envisioned cost of correctly re-working existing airlines. (The cost savings might come from a factor of cost not considered here, Boeing's liability to airlines for downtime of units or inability to sell new planes.)
Part not talked about is the wires in question for the tail also offer redundancy. Boeing wanted to cut time on manufacturing ran them all along the same section of the tail.
Interesting. I though that part was written in blood with https://en.wikipedia.org/wiki/United_Airlines_Flight_232 (uncontained engine failure has hit a SPOF in the tail section, severing all hydraulics)
Feeding an automated system (with authority to crash the plane) from a single sensor is also known to be wrong. Controls engineering has taught failure modes and redundancy since the '60s. That didn't stop Boeing.
> Not an aircraft safety expert but I am curious if shifting the wires may not introduce more potential issues in existing planes, as the existing risk factor seems to be proven low (i.e. they are not requiring all 737-NG airframes to have the work)
The 737-NG was introduced in 1997, one year before the new regulations went into effect so it's grandfathered in. Seeking to have the 737-NG retrofitted would be like requiring all cars without airbags to be retrofitted.
What Boeing did with the 737-Max through out it's certification process was argue that it was so similar to the 737-NG that it should be grandfathered into certifications as well. This is done in a lot of industries where certification or regulatory approval is costly and complex, regulators offer a Me-Too path to certification where you argue that your product is based upon or similar enough to an existing product that only the differences need scrutiny. By going this route, Boeing was able to avoid redesign and retooling for things like the wiring harnesses which saved cost and time to market.
Now that the 737-Max is having to be re-certified, AND Boeing's delegated authority to self-certify has been revoked, the FAA is going over everything. The wiring harnesses which were Me-Too'd, aren't in compliance with 1998 requirements. Boeing is trying to argue that the 737-NG has proven the design safe and thus the new requirements shouldn't apply.
The 737-NG was introduced in 1997, one year before the new regulations went into effect so it's grandfathered in. Seeking to have the 737-NG retrofitted would be like requiring all cars without airbags to be retrofitted.
What Boeing did with the 737-Max through out it's certification process was argue that it was so similar to the 737-NG that it should be grandfathered into certifications as well. This is done in a lot of industries where certification or regulatory approval is costly and complex, regulators offer a Me-Too path to certification where you argue that your product is based upon or similar enough to an existing product that only the differences need scrutiny. By going this route, Boeing was able to avoid redesign and retooling for things like the wiring harnesses which saved cost and time to market.
Now that the 737-Max is having to be re-certified, AND Boeing's delegated authority to self-certify has been revoked, the FAA is going over everything. The wiring harnesses which were Me-Too'd, aren't in compliance with 1998 requirements. Boeing is trying to argue that the 737-NG has proven the design safe and thus the new requirements shouldn't apply.
This is definitely a concern. Having to undo so much of the wiring could introduce the risk of some of the insulator breaking on other wires, or accidental damage or something else.
But the FAA would definitely weigh this against the possible issues of high-voltage wires running in the same bundle as control wires.
But the FAA would definitely weigh this against the possible issues of high-voltage wires running in the same bundle as control wires.
Aside from the gallon of blood and pound of flesh we'll see called for in the public/political arena, I really doubt there's any viable fix that won't require pilot training.
As I understand, the 737-MAX blunder is at the core a result of bad incentive alignment baked into their deal with Southwest: Boeing was trying to avoid any FAA "differences" simulator training requirements to make more money in a fleet sales order to Southwest Airlines. If the FAA required level-D simulator training, Boeing agreed to rebate Southwest $1 million for each MAX bought. The training would have cost Southwest $2000 per head. That's $18M for their 9,000 pilots.
source: https://newrepublic.com/article/154944/boeing-737-max-invest...
As I understand, the 737-MAX blunder is at the core a result of bad incentive alignment baked into their deal with Southwest: Boeing was trying to avoid any FAA "differences" simulator training requirements to make more money in a fleet sales order to Southwest Airlines. If the FAA required level-D simulator training, Boeing agreed to rebate Southwest $1 million for each MAX bought. The training would have cost Southwest $2000 per head. That's $18M for their 9,000 pilots.
source: https://newrepublic.com/article/154944/boeing-737-max-invest...
> I really doubt there's any viable fix that won't require pilot training.
This issue has nothing to do with type ratings and pilot training.
Boeing had delegated authority from the FAA to certify portions of the 737-Max for airworthiness and certified the wiring harnesses based upon the fact that they're identical to the 737-NG's harnesses which were certified in the 90s.
Unfortunately the 737-NG was introduced in 1997, and new regulations introduced in 1998 made that design invalid for new aircraft. The 737-NG is allowed to fly because it's grandfathered in under the old design standard.
Boeing is trying to argue that the 737-Max should be grandfathered in as well since it's similar enough to the 737-NG and the NG has a proven safety record.
This issue has nothing to do with type ratings and pilot training.
Boeing had delegated authority from the FAA to certify portions of the 737-Max for airworthiness and certified the wiring harnesses based upon the fact that they're identical to the 737-NG's harnesses which were certified in the 90s.
Unfortunately the 737-NG was introduced in 1997, and new regulations introduced in 1998 made that design invalid for new aircraft. The 737-NG is allowed to fly because it's grandfathered in under the old design standard.
Boeing is trying to argue that the 737-Max should be grandfathered in as well since it's similar enough to the 737-NG and the NG has a proven safety record.
List price for a single MAX8 is $120M. I'd be surprised if $18M total of upside was the primary driver across an initial qty 40 aircraft order. They could have just offered that as an additional discount.
The 737-MAX800 is something like $10M more than a A321-NEO, when the A321-NEO meant retraining your pilots and the 737 didn't, that $10M difference closed a lot, now both are going to require retraining.
This is nothing to do with the MAX's inappropriate affection for the ground; it's a separate safety issue.
It's not, separate, one drives the other. Their efforts to make the plane "identical" to the 737 in terms of training is what caused them to add these dangerous "features."
It's really quite amazing.
It's really quite amazing.
This is nothing to do with training. We are just talking about the location of two wires deep within the body of the aircraft.
The 737 has always had wires in this location. The original 737, the 737-Classic, the 737-NG and now the 737-MAX.
But the rules changed after the 737-NG was certified due to two major crashes. All new aircraft designed need to meet these new rules, but old aircraft designs get grandfathered in.
The 737 has always had wires in this location. The original 737, the 737-Classic, the 737-NG and now the 737-MAX.
But the rules changed after the 737-NG was certified due to two major crashes. All new aircraft designed need to meet these new rules, but old aircraft designs get grandfathered in.
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.
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.
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.
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.
> 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)
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)
I agree, there's a lot of unknowns.
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.
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.
you could buy long term options on airline companies
Not right now. The implied volatility, aka the cost of options, is too high.
For example, American Airlines, symbol AAL, closed Friday at about $16 per share. If you go to January 2021, the cost of a $20 strike call is about $3. So you need AAL to rise from $16 to $23 just to break even. That's almost a 50% gain needed, in less than a year.
The cost of options will get much cheaper once the market settles down (even if current price levels stay the same). If the market sits in the doldrums for a few months (not moving up or down very much) then option prices will fall.
You need to buy options when they're cheap, not when they're crazy expensive.
Not right now. The implied volatility, aka the cost of options, is too high.
For example, American Airlines, symbol AAL, closed Friday at about $16 per share. If you go to January 2021, the cost of a $20 strike call is about $3. So you need AAL to rise from $16 to $23 just to break even. That's almost a 50% gain needed, in less than a year.
The cost of options will get much cheaper once the market settles down (even if current price levels stay the same). If the market sits in the doldrums for a few months (not moving up or down very much) then option prices will fall.
You need to buy options when they're cheap, not when they're crazy expensive.
If you think options are overpriced you can sell options too. They're crazy expensive because people think they'll print.
I’m curious - why is that so? I would assume that with higher volatility there are more people participating in the futures markets, and the margina should be lower - not higher
Margins will be lower but the prices will still be higher.
In low vol periods: if stock is at $2, it is likely to stay at $2 since vol is low. So maybe a $3 option is worth 10 cents. But there are very few people in the market so there's going to be a large big-ask spread. Nobody's going to sell it at 10c; there are few other sellers so you can offer it at 15c and rip off the buyer since they have no choice.
At high vol periods everyone wants to be in the market so the price will actually be close to the 10c theoretical price - less spread (what you. All margin). But since there is high vol the stock is more likely to get to $3 so the option could be worth 20 cents instead of 10.
Volatility affects price; market volume affects spread.
In low vol periods: if stock is at $2, it is likely to stay at $2 since vol is low. So maybe a $3 option is worth 10 cents. But there are very few people in the market so there's going to be a large big-ask spread. Nobody's going to sell it at 10c; there are few other sellers so you can offer it at 15c and rip off the buyer since they have no choice.
At high vol periods everyone wants to be in the market so the price will actually be close to the 10c theoretical price - less spread (what you. All margin). But since there is high vol the stock is more likely to get to $3 so the option could be worth 20 cents instead of 10.
Volatility affects price; market volume affects spread.
4. this virus could have similarly severe outbreaks for years.
I've thought about this too. What is the probability this becomes endemic to China, and occurs annually in the fall/winter? Related question: why didn't swine flu become endemic (maybe it did, I haven't read anything about swine flu since 2009)?
Something to keep in mind Covid-19 has already taken a foot in multiple countries in the southern hemisphere, where they are going to enter fall pretty soon. This already reduces the possibility that it will totally fizzles out due to northern hemisphere summer.
There are far fewer people at the climates for a northern winter south of the equator.
Sydney winter for example is around 10C, and rarely drops to 5C. Joburg's winter mean is about 10C.
Compare that with London, New York and Beijing.
Sydney winter for example is around 10C, and rarely drops to 5C. Joburg's winter mean is about 10C.
Compare that with London, New York and Beijing.
I saw a recent paper which presented a model which did predict seasonal reinfection... provided the infection rate is low enough now and that infection rates are reduced in the summer vs winter. If all the mitigation efforts work well now and covid 19 is similar to flu in seasonality the model predicted we would have a lull from May a new outbreak in November.
because regardless of what you hear, china takes outbreaks very seriously and responds aggressively. the general population in china also takes it very seriously. normal behavior response in china looks like over reaction in the us. please watch this video by 3blue1brown https://www.youtube.com/watch?v=Kas0tIxDvrg china is past its inflection point and we have yet to determine where our inflection point will be. everyone should be changing your behavior now. the fact that sars-cov didn’t get as far in 2002 as sars-cov-2 virus is currently going should be concerning. the us could ignore prior outbreaks because china is aggressive to stop it.
I was in China during the swine flu scare (I'm Canadian originally). I agree that China takes these sorts of things very seriously based on what I saw.
That doesn't necessarily mean they'll succeed every time though, or that they'll respond as aggressively to a dangerous background virus as to a novel one.
That doesn't necessarily mean they'll succeed every time though, or that they'll respond as aggressively to a dangerous background virus as to a novel one.
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Actually if this results in a lot of young people staying at home what you will probably see is a mini baby boom, same as what happened in previous recessions.
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.
There's nothing wrong with the concept of MCAS. Just it's implementation.
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.
There is a lot wrong with a plane intended to transport people that requires such a system in order to be safe to fly.
It requires the system to avoid training pilots.
And, yet, it does require proper training after all...
Only training to do what they are supposed to do anyway - use the cutoff switches when experiencing runaway trim.
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.
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.
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.
> 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.
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.
> The opposite of positive static stability is Fly By Wire based 4th-gen onwards jet fighters like F-16
The risks introduced by fighter jet lack of static stability are mitigated by the installation of ejection seats. That's a tough sell for passenger aircraft.
The risks introduced by fighter jet lack of static stability are mitigated by the installation of ejection seats. That's a tough sell for passenger aircraft.
The 737 MAX is statically stable. There are quite a lot of uninformed comments floating around that compare the plane to fighter jets like the F-16, but these are pure nonsense. An F-16 would tear itself to pieces in seconds if the flight control software malfunctioned.
It seems more to be that people use the word "stable" while maybe another word should've been used. The main criticism during the "stable" criticisms is that something like MCAS was added. The design of the plane should've been in such a way that MCAS wouldn't be needed. So instead of adding MCAS, the problem leading to MCAS should've been solved with a (huge) redesign.
Note: Purely responding to the "stable" word. If people compare it to stuff like an F-16, then yeah.. they don't know / nonsense.
Note: Purely responding to the "stable" word. If people compare it to stuff like an F-16, then yeah.. they don't know / nonsense.
>MCAS, an FBW-like system
As WalterBright says, there is nothing 'FBW' about stability augmentation systems. In various forms these have been installed on all commercial jets for decades. 'Fly by Wire' simply means that there is no mechanical/hydraulic linkage between the stick and the control surfaces. The 737 MAX is not an FBW aircraft by any stretch of the imagination.
As WalterBright says, there is nothing 'FBW' about stability augmentation systems. In various forms these have been installed on all commercial jets for decades. 'Fly by Wire' simply means that there is no mechanical/hydraulic linkage between the stick and the control surfaces. The 737 MAX is not an FBW aircraft by any stretch of the imagination.
> 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.
Lifting the nose too high can induce a stall, which is very dangerous at low altitude.
Yep. Also pitching the nose to far down to prevent a stall.
Its implementation and the corporate culture that pushed for that.
Just as there's nothing wrong with communism, just the Soviet Union's implementation.
Just as there's nothing wrong with communism, just the Soviet Union's implementation.
Have you seen a good implementation yet?
Does saving face mean nothing to Boeing? Wont this kind of behavior decrease Boeing sales as the public continues to loose confidence in their planes?
At this point just do it. Do anything to at least appear like you're taking the matter seriously. Just let the regulators have their way for a while. Surely it's better to just take the short term hit.
I know the stock market doesn't generally reward short term sacrifices for long term gains, but does public image really mean this little anymore?
At this point just do it. Do anything to at least appear like you're taking the matter seriously. Just let the regulators have their way for a while. Surely it's better to just take the short term hit.
I know the stock market doesn't generally reward short term sacrifices for long term gains, but does public image really mean this little anymore?
One factor that could be important here is that one CAD exchange standard doesn't currently do a very good job of modelling wiring harnesses. This problem first showed up on the A380 when different CATIA versions were being used at the two Airbus design centres.
A solution is being worked on by a joint Boeing and Airbus group but will be a while before it is published.
A solution is being worked on by a joint Boeing and Airbus group but will be a while before it is published.
Boeing’s argument is that the issue really isn’t an issue based on available data.
The FAA’s argument is that a rule is a rule and Boeing seems to have a problem following the rules.
Boeing is probably right but given the mess they got themselves in it’s probably best to just fall in line and follow the rules. They’re not helping their cause trying to apply logic here.
The FAA’s argument is that a rule is a rule and Boeing seems to have a problem following the rules.
Boeing is probably right but given the mess they got themselves in it’s probably best to just fall in line and follow the rules. They’re not helping their cause trying to apply logic here.
> Boeing is probably right
From the article: "New safety rules on wiring were adopted in the aftermath of the 1998 Swiss Air 111 crash."
These recommendations were added as a result of a crash. The crash happened a bit after the 737NG started flying (AFAICS 737NG=1997), so I guess existing certified aircrafts didn't need to be modified. It does make sense for a new aircraft though.
From the article: "New safety rules on wiring were adopted in the aftermath of the 1998 Swiss Air 111 crash."
These recommendations were added as a result of a crash. The crash happened a bit after the 737NG started flying (AFAICS 737NG=1997), so I guess existing certified aircrafts didn't need to be modified. It does make sense for a new aircraft though.
Good.
If you think this isn't an argument about money and who pays, I think you misunderstand why we are here.
There is no other reason we are here, than money. An unwillingness to incur cost, or cause customers to incur cost, that made other choices of provider more attractive drove Boeing to make decisions which now will cost money, to them, to the customer, and probably to everyone else at large.
Boeing is not in pursuit of the "best" fix, its in pursuit of the "least worst (in cost terms) fix"