From applied control theory I intuitively knew that a cascade of issues resulting in a system instability had overwhelmed the pilots. I now see this arrogance of data science based software engineering being inserted into business, industry and social systems. As an abstract example Facebook's attempt to stabilize the politics on its platform through algorithms. More concretely in the hydro dam control systems in the Pacific Northwest. Specifically in this damned Boeing 737 Max control system. Control systems need rigorous testing through simulation not accidents.
Boeing's design process was a shady mess for sure, but safety goes all the way down and up the stack. Every failure mode should have some level of redundancy and double checking.
So, yeah, a manufacturer tried to game the certification process to save a few bucks (and months) on a new aircraft design. That's a failure. But it's not an unforseen one!
The safety value for manufacturer shenannigans is supposed to have been the certification process itself. And I gotta say the worst failings here are with the FAA. At any point someone could have looked at the process and seen:
1. They changed the engine
2. They had to move it because it was too close to the ground, but they couldn't stretch the landing gear and keep the type certification.
3. So they moved the engines forward and up
4. But now the aircraft was less stable, and they couldn't change the tail design and keep the type certification.
5. So they did software-managed stability augmentation instead
6. But (that's right) they couldn't change the autopilot and keep the type certification.
7. So they did it with the trim, which had never operated under autonomous control before.
I'm sure I have a few of those details wrong, but the point is that any bureaucrat familiar with the aircraft could have seen that this was a ridiculous house of cards they were playing with the type certificate. I mean, one change with one workaround, sure. But a cascade like this is just obviously a perversion of the process.
Yet no one said something. Or if they did they were overruled.
The way the built-in incentives work, it's not feasible to rely on 100% forthright and honorable manufacturers. So we have a regulatory body to catch those failures for us, and it failed.
I think this also reflects that Boeing has moved from being a honorable company where good engineering was the first priority, to a company driven by greedy MBAs and PowerPoint charlatans. Those crazy ways to bypass regulations indicate they were totally pushed by a business plan that did not mind cutting lots of security corners.
It's sad, but I think many corporations, and in general most human organizations, go through this lifecycle.
Obviously, none of this discharges FAA from all the very likely negligences they committed when reviewing the new MAX certification you have explained so well.
It also means that they have competition: airlines are not fond of having to recertify their pilots and "flys like any old 737" was Boeing's main advantage over less outdated Airbus designs. Doing the engine replacement the right way would have created a pilot recertification requirement and thus canceled that advantage, no matter how much money Boeing threw at it. As much as I enjoy a good game of MBA-blaming, "fake it till you break it" is more than simple cost-cutting here. There's just as much engineering hybris at play when "can we do it? yes!" is heard while "should we do it? no" is hardly ever thought (same with diesel and urea tank refills). I see the problem more in institutionalized optimism than in penny-pinching.
> And I gotta say the worst failings here are with the FAA.
The FAA is underfunded to do their job properly. The major consequence of this is that to properly certify the changes from Boeing would have taken a long time. A long time would mean that Airbus would win more contracts compared to Boeing. With a pro-business administration in place, there was significant pressure put on the FAA to complete the certification quickly. They were actively encouraged to outsource safety work back to Boeing's engineers to keep pace on the timeline.
The ODA program, devolving certification work to industry, started in 2007 and followed an earlier trial called DSA.
Cessna has full type self-certification authority, too, but seem to behave responsibly. Perhaps because the bizjet market is truly competitive and if they are caught taking shortcuts then EMBRAER, Dassault, Raytheon, Bombardier etc will take their customers.
Whereas if an airline cancels their 737 Max now, they'll be waiting eight years for an A320Neo
it received its type cert on 8 march 2017. trump took office less than two months prior. i HIGHLY doubt the process happened entirely within that ~ 1.5 months.
To be clear, I'm not pointing fingers at any particular politics. American government in general is pro-business. That's both good and bad, and this happens to be an example of pro-business policy outweighing safety policy.
Sounds familiar. I am in medical devices and we often have situations where the technically correct thing would cause a huge amount of paperwork and FDA scrutiny so we look for ways to work around this. This can mean a technically inferior solution but it's more viable from a financial and time to market point of view.
The game is set up such that these quandaries are inevitable. This is a problem with capitalism and competitive markets. People bemoan the process and demonize those that have to balance financial pressure against other forces but the truth is, the result often goes unnoticed. We are all use to getting less than desirable results on a daily basis; it is just when a catastrophic failure occurs that we all start calling out from our soap boxes about how we should do better.
Aside, we all know safety and security are important, but we complain the other way too. How many people complain about how much we spend on defense as a country? The budget is reflective of the number of ways we need to defend ourselves and the number of ways we would need to overcome an adversary's defenses when we are on the offensive. That number grows as technology gets more advanced. The people involved in developing solutions are increasingly more specialized and salaries are getting higher. If we did nothing, somebody might drop a bomb on our head and we'd all wonder why we never spent money developing a defense.
TLDR: The world is funny and people complain about everything.
As a passenger, if these were the trade-offs Boeing made, my stomach just dropped. I don’t consider myself naive as to which trade offs corporations might consider fair game to increase profits, but if,,, changing engine placement in spite of impact to stability and such.... can anyone else talk to this. I’m actually bothered by this. This sounds like dangerous engineering.
It's not, really. Not technically. All of those tradeoffs and vastly more are made all the time, when certifying a new aircraft.
There's nothing wrong with relaxed stability, autopilots are 60 year old technology and have been keeping people safe since our grandparents were flying. And the certification process has for the most part produced very safe aircraft.
But in this case, the certification process was seen as too expensive. Boeing wanted to market a tweaked, high-efficiency 737 with newer engines, and didn't have the time to spend on certifying a whole new aircraft. So it used the same old one and the faster regulatory process.
But that assumes that the regulatory process worked. Clearly that cascade of changes was not in the spirit of "just small modifications to existing designs". But the FAA didn't squawk and certified it anyway.
And as it happened, just one of those choices (using the trim for stability control) turned out to be unsafe in unexpected ways. One was that the AoA sensor driving the thing was glitchy. But more importantly, the trim was originally certified on the assumption that a trim control failure could be overridden by the pilot, but no one realized that pilots weren't trained to think of trim as being a computer controlled thing and didn't understand what was happening when the MCAS started fighting them.
> But in this case, the certification process was seen as too expensive.
Not just that, but also pilots would need new training if it were a new type certificate. This was a huge marketing advantage for Boeing because their end customers could avoid the cost of re-training their pilots on a new airplane.
And the lives lost an unforeseen externality. One would hope a company in such a safety critical industry would err on the side of caution. Or are they so strapped for cash they can't afford it?
Everything in engineering is a trade off. The changes that were made were not inherently dangerous, but the certification process on those changes fell apart for a variety of reasons. If the certification process had been followed correctly, these planes would be flying safely.
The FAA is underfunded. A pro-business administration applied pressure to help Boeing certify more rapidly. Due to time and money pressures, many things that should have been performed by the FAA safety inspectors were actually performed by Boeing engineers. The safety assessment was performed on incorrect numbers! (Boeing estimated some parameters and performed safety assessment. Then those parameters were updated after flight testing, but the safety assessment was not re-performed with the updated numbers! That's a huge problem in the process.)
> The changes that were made were not inherently dangerous
A few hundred dead people and hundreds of grounded planes say no to this.
> The FAA is underfunded.
This is a feature not a bug. Under the neoliberal orthodoxy this is as things should be. The free market is the most effective and efficient way to regulate corporations. The FDA is a drain on the economy.
> they couldn't stretch the landing gear and keep the type certification.
They couldn't stretch the main gear because then it could not have properly retracted into the fuselage. They were able to extend the nose gear a few inches and still allow it to retract.
Point 7 is incorrect. Automatic trim adjustments by the Speed Trim System (STS) had been in place for a long time. However using automatic trim changes during manual flight to reduce a pitch-up tendency near the stall was new.
The NTSB does and has done a fantastic job keeping flight safe, they are the sorts of people we should be looking to for what went wrong and how to fix it. Not politicians, Ralph Nader, or armchair engineers on forums.
Flying is complex and exposing the correct instrumentation, controls, and training to pilots is a hard problem. There will be mistakes and the important thing is to learn from them. The industry and regulators are very good at this.
Nader may be right about some of this, but just claiming that evil "reckless" Boeing executives caused this is pretty silly. Boeing execs are probably the least reckless execs in any field, because even tiny failure rates can have massive consequences.
What's scariest about this is that it highlights the fact that many pilots are just regular schmoes. Average intelligence, adequate training. That's fine 99.9% of the time, when equipment failure isn't catastrophic. But it's crazy how many, when they're actually faced with catastrophic failure, forget how to fly the damn plane.
The runaway trim problem has been happening for 50 years. This isn't new, or unique to the MAX (same thing can happen on the small jets I fly). Anytime something like this (or any other autopilot failure) happens, every pilot is trained to disengage the system and fly the goddamn plane. Apparently the pilots on these flights didn't know how to do that. It's tragic.
> But it's crazy how many, when they're actually faced with catastrophic failure, forget how to fly the damn plane.
Your comment makes me sad. Especially since there will be many other people who come to a similar conclusion without adequate information.
The runaway trim problem and the new MCAS problem are superficially similar, but the symptoms are distinctly different. The runaway trim manifests itself with a continuous deflection of the trim. Pilots are trained to recognize this symptom and compensate. The new MCAS also affects the trim, but it is engaged in repeated nose-down commands. It has fundamentally different symptoms compared to the older and more widely known runaway condition.
There is no absolute reference on the position of the stabilizer. It is a wheel that turns, so a pilot must watch that wheel continuously to know if it keeps turning or if it turns periodically.
The controls column has force feedback. The pilot was pulling back with ~50 lbs of force to fight the angle of the trim. Imagine holding a 50 lb dog while simultaneously trying to review emergency procedures to find the source of the problem. The pilot was flying the damn plane, and the symptoms of this problem were different.
And the pilots must have recognized it was a trim issue because they countered it multiple times. Why they didn’t flip the stab trim cut off switch is a mystery.
An earlier crew was able to fly the plane. I agree the pilots should have been made aware of MCAS (though either the Ethiopian pilot was shockingly not aware of it or being aware didn’t help him). But at the end of the day the pilots are there to fly the plane, not manage automation:
The earlier crew faced an identical issue the day before, and it was only the deadhead pilot onboard who recognized the issue and suggested flipping the stab trim cut off. Out of 5 pilots (7 if we count the other crash), only one suggested the correct fix.
> Why they didn’t flip the stab trim cut off switch is a mystery.
Not really. In the previous incarnations of the 737, a hard pull on the yolk by a pilot disengaged the automatic trim system. In the 737 MAX, the yolk pull method to disengaged the trim was disabled. What the pilots did would have worked on the previous version of the plane, but not on the MAX.
Boeing really tried to claim that the MAX was just like the previous version, and that pilots didn't need new training to fly it. I think the data shows that more pilot training is appropriate for this plane.
> The earlier crew faced an identical issue the day before, and it was only the deadhead pilot onboard who recognized the issue and suggested flipping the stab trim cut off. Out of 5 pilots (7 if we count the other crash), only one suggested the correct fix.
And there are two ways to look at that. One is to say "obviously this means that this failure mode is too hard to diagnose". Another is to say "holy shit Lion Air pilots are fucking incompetent, I'm never going to fly any sort of third world budget airline if any of them are like this".
The truth is probably somewhere in the middle, of course.
> What the pilots did would have worked on the previous version of the plane, but not on the MAX.
And yet the checklist continues past that point, because guess what? The "control inputs disengage trim" component can also fail, and Boeing planned for that.
I believe you're right that the truth is in the middle. It really points to the pilots being inadequately trained on this aircraft. Boeing strongly pushed to avoid requiring new pilot training for the MAX airplane. They claimed that MAX was similar enough to the previous version of the 737 that if a pilot were checked out on the previous plane they were good to go. What we're seeing now is that assessment was wrong. More training should have been required.
Boeing fucked up big time on this one. FAA also fucked up. Pilots were inadequately trained, and some delivered info was false (Boeing said MCAS could only bring the nose down 0.6 degrees, in fact, it was unbounded)
The MCAS system was designated "hazardous" by Boeing in their own safety assessment. A system that is labeled hazardous can not be reliant on a single system failure. MCAS is reliant on a single sensor. That's already a major error in the safety analyses. As we can clearly see from two accidents, MCAS system should have been designated "catastrophic", one step more dangerous in that scale, with even more stringent redundancy requirements.
Didn’t the pilots in the lion air crash shut off autopilot though? The issue was that they were unable to diagnose it as a problem that required disengaging the trim system.
Does the FAA require civilian commercial airliners to have some sort of catch-all (e.g. positive stability if you kill all power and lower a ram-air turbine and assuming your flaps aren't jammed)? I don't know if that would have saved lives on those flights, because it was high enough to crash and low enough to not turn around to the airport or get to safety, but I would think a gliding plane and some base assumptions about the inherent flight characteristics of their plane would give the pilots a few precious seconds to think (like the miracle on the Hudson). Physics-based problems should have physics-based solutions.
If the engine placement and weight distribution caused an inherent problem with the stability of the aircraft, a rule like that might have given Boeing pause, no?
Yes, in particular the 737 is a cables and levers and pullys design. It can fly totally manually. If the pilots had realized they had a trim problem, and switched off the electric trim, and trimmed manually (literally turning a crank in the cockpit) they would not have crashed.
Should the airlines share some of the blame for not paying for the $80K disagree light for the two sensors on their $100M plane?
If I don't pay for the $3K automated emergency braking upgrade for my car, is it Honda's fault if I rear-end someone and die? It doesn't cost them $3K for what's mostly software and a couple hundred dollars of sensors, should they have bundled that obvious safety feature into the price of the car and not made it an optional upgrade?
That's not equivalent. All 737 MAXs have the failed design.
Instead it's like all cars like yours have their stock automated emergency braking system malfunction, didn't illuminate the "check engine" light (that's was the extra 100 bucks), and preventing the brakes from working at all despite you slamming furiously on the pedal. My guess is you'd be a lot angrier about that if you lived.
Isn't it more like the brakes failed to operate and since I didn't pay for the "brake system inoperative" light, I have to figure it out on my own and turn off the primary braking system and apply the emergency brake?
If I have enough experience to know (or happen to have another driver with me that knows) what to do when I press the brake pedal and nothing happens, it's recoverable, otherwise I'm going to keep stomping on the brakes and fighting it without knowing that all I have to do is flip the switch to disable the broken braking system.
So it's not that I had no way to know how to get out of the situation, I didn't have the specific training to recognize it, and if I'd just paid the extra $100 for the light, it would have been much more obvious.
The real solution would be to inhibit trim if the AoA vanes disagreed. This is typically the policy for stick shakers and stick pushers.
My guess is they justified this policy because:
-the trim wheel is obviously moving, so a pilot will recognize this as a runaway trim (and perform correct memory items to disable trim)
-the system will only activate when flaps are retracted. So when the plane starts doing something wrong (nose down), the pilot will undo the last thing they changed (flaps), which prevents further nose down trim
I would go with Toyota and unintended acceleration rather than Honda. Honda are doing pretty good - only car company in America meeting emission standards (except Tesla).
The tactile response friction device in the electronic accelerator pedal was the point of failure. I doubt people buying the car even knew the accelerator was some electronic gadget rather than connected by a cable to the engine as per grand-dad's Toyota. Nobody was given special training on how to react should the electronic accelerator go wrong.
Now, if you are a driving instructor you can specify a second set of pedals. They might be in the other seat but you can specify them and have someone sat there to use them.
Anyway, that is as far as the auto analogy goes, tenuously...
I used Honda as an example of my car because my car is a Honda, and note that my example didn't posit any malfunction, just an extra-cost safety feature (though I think it's standard on most of their cars now)
I personally don’t think safety equipment should be optional when they are relatively inexpensive for the manufacturer to implement. Boeing were clearly viewing this as an opportunity to get a bit more money out of a customer as pure profit margin.
That's part of the problem with the debate about this though: that's a never ending slope. What constitutes relatively inexpensive for the 1,000s of parts in an aircraft?
There's a cost to human lives. We can quibble about what it is, but there's clearly a point where it is unreasonable and worse for society as a whole to make planes safer but more expensive.
They got it wrong here. But it's non-trivial to figure out without hindsight.
But who defines "inexpensive"? Is a $1000 feature inexpensive on a $30,000 car? Is an $80K feature inexpensive on an $100M airplane?
That's $4M across a fleet of 50 jets (Ethiopean's 737 order size) - so it's not exactly insignificant.
Japanese authorities required the feature, while the FAA and others did not. Should all of the onus be on the manufacturer? There's definitely an argument to be made that Boeing didn't reveal the full nature of MCAS to the FAA, but if that weren't true, is it Boeing's fault that they didn't bundle the feature, or is it the FAA's fault? And why did the Japanese require it, did they have information that the FAA did not have?
I guess I meant from the manufacturer's perspective. I doubt it costs Boeing 80k to implement, though that was apparently the list price for the feature. This comment also really belongs within the context of the safety expectations of your industry. For planes, there is a high safety expectation. For a hardware feature that costs Boeing maybe $1k (wild ass guess here) to implement, I would expect them NOT to view that as an opportunity to squeeze someone for more profit. They would obviously have to increase the selling price somewhat.
From a purely business case I can see why Boeing did what they did but I'm just philosophically opposed to profit being the only goal. Even if it was the only goal, this case pretty clearly shows that it wasn't 'worth it' for Boeing to skimp on safety features with what, 20B wiped off their valuation.
The problem with this is as that $4m sounds like a lot of money to pretty much everyone on the planet but if you are buying 50 medium size commercial jets it's literally a rounding error.
'm a bleeding-heart socialist, actually an anarchist, far to the left of Ralph Nader and I /still/ find his rhetorical style obnoxious and not useful.
We can have a discussion about how de-regulations and profit motives may have contributed to this disaster, we have even throw in ideas about regulations and corporate responsibility, but we have to recognize that software at this scale and or these purposes is hard, and there's no reason why the govt may be better at it than Boeing, and the discussion about what the risk/reward ratio should be for society as a whole is super complicated and we don't nec have a way to have it.
TLDR: I'm an anarcho-socialist programmer. Boeing may or may not be evil and de-regulation and the profit motive probably eff things up in the current socio-economic sphere, but Ralph Nader doesn't lend much to the conversation here.
> Most notoriously, the airlines, after the hijacks to Cuba in the late Sixties and early Seventies, made sure that Congress and the FAA did not require hardened cockpit doors and stronger latches on all aircraft, costing a modest $3000 per plane. Then the 9/11 massacre happened, a grisly consequence of non-regulation, pushed by right wing corporatist advocacy centers.
This is a curious and very sad bit of history I was unaware of.
I’m going to put a big fat Citation Needed on that one. I don’t see how it would have helped in the 1970s. The hijackers take over the rest of the plane and say they’re going to execute one passenger every hour unless the pilots take them to Cuba. Are we expecting the pilots to say, nope, we’re safe, execute whoever you want?
9/11 was a game changer becasue it was a completely new kind of hijacking where the hijackers have no demands and everybody dies quickly if the hijacking goes according to plan. Reinforced doors are useful there, becasue threats to the passengers don’t hold weight when you know they’ll all die anyway if you open the door. That was very much not the case in the 70s.
Wouldn't it make sense in that case to just pretend it was a "regular" hijacking? Why should you go "hey pilots, open the doors or not, everyone is gonna die anyways." Vs. Open the door now or we'll kill a passenger every 10 minutes."
That won't work, because the protocol has changed. No pilot today will open the door, even as someone dies every 20 minutes. The pilots will divert to the closest airport and land.
There's plenty of blackbox recordings and transcripts out there of pilots losing control and freaking out instead of trying to stay calm and try to fix the situation. Most recent example is lion air. How the fuck can you seriously think every pilot on this planet would stay calm, act absolutely rationally and not panic if they can hear people being shot behind a closed door, especially if they'd been told they can make it stop by opening the door? That's like a hundred times more psychological stress. Seems like you should get out some time, have interactions with real people.
Considering letting the pilot take control of the controls far more likely increases the casualty count to everyone on board + far more people on the ground, so I believe landing is still the better option and is something that pilots can learn.
Yes, that is some flawless logic. Also, if you were a pilot losing control of your airplane, the best thing to do would be to stay calm, quickly analyze the solution, go through appropriate checklists and try to fix the situation. That's something pilots can learn. I would actually go as far as claim that's what they're actually taught. However if you search on YouTube, you'll find quite some voice recordings of crashed flights where you can clearly infer from the recording that panic seemed to guide the actions in the cockpit. I think this is far more likely to increase the chances of the pilots failing to regain control of the aircraft, leading to a lot of deaths. So I wouldn't bet on those very same people to always think as rationally as you described here. Rational thinking and panic usually don't work together that well.
Would you believe a hijacker who said that? No. After 9/11, you assume that all hijackers are on a suicide mission and the only way you survive is to defeat them before they can carry it out.
Wasn't part of it that before 9/11 a hijacker using the plane as a weapon or wanting to kill everyone wasn't the expected, and thus the assumed "best" route was to comply (as not to provoke the hijacker to start killing hostages to increase the pressure), go wherever they want and hope law enforcement will sort it out?
E.g. the cited Cuba hijackers didn't very often kill people. Some of them might have given up when unable to get to flight crew, but others might have used more force to get what they wanted.
That's always been my understanding of it. Hijackings were common in Europe for example and that's how it almost always went down. (Not too familiar with the history of hijackings in USA, but sounds the same.) Then we saw the change right on 9/11 when passengers on UA93 learned their hijackers intended fate and fought back.
As for a flyer's bill of rights it would be nice to have more widebody flights or at least something small but comfortable like the Embraer 195.
What's been lost in this discussion is that the 737 is based on the 1958-era 707 in it's major configuration -- with its circular fuselage it is not built with compatibility with the human body in mind so of course you are going to feel like flying is hell after a transcontinental trip on what was originally intended as a regional jet.
Even if you survive the flight on a 737 you are going feel like you're dead. Since the 737 and A330 represent the vast bulk of planes built, anyone concerned about the environmental impacts of air travel (e.g. climate change, noise) would want to see the 737 get a clean sheet design like the 787.
I’ve never noticed a difference in comfort between different airplanes. What matters is the seat, and they’re pretty much all the same (and, when different, this does not depend on the type of plane they’re in). Why would I care about fuselage cross section?
United has a few configurations for 777 economy seating - a 3-3-3 configuration with 18.3" of width and a 3-4-3 with 17.1" of width.
I've flown the 3-4-3 one and will never fly it again, it is super cramped, and even the few inches of extra leg room in economy plus can't make up for the narrow seats.
So being a wide/narrow body jet doesn't really relate to seat width, it's all based on how many seats the carrier can cram in.
This is entirely up to Delta though (or any airline).
Delta could have easily decided to fill Economy seats on their 737's with 18.5" wide seats... and then had a 2-and-2 configuration instead of 3-and-2 or 3-and-3.
Same is true for the 777, they could go with smaller seats and pack in more seats per row. Likely, the 777 is used for longer flights and they decided a more comfortable seat for an 8-16 hour flight is worth a few less passengers. Or, the 777 might be overweight if filled with too many passengers, so larger seats are justified.
At the end of the day, it's the economics of making these flights - airlines run on notoriously thin margins, and flying a passenger jet is very expensive.
That makes no sense. Seat width is fuselage width divided by number of seats, minus room for the aisle(s). Wider seats means fewer seats. The airlines make that trade off based on what they think people will tolerate.
Unfortunately, what you want is completely incompatible with the price you're willing to pay for an airline ticket... and likely the amount of time you wish to spend traveling (hub-and-spoke model takes a lot longer than direct flights, due to layovers, boarding and deplaning, etc, and offers fewer departure/arrival times).
Also, a modern 737 can be very comfortable - it depends on the interior layout and choices the Airline (not Boeing) made when leasing the aircraft. Airlines are responsible for the interiors...
If airlines could fill up the seats I’m sure they’d fly more wide bodies. Unfortunately people want direct flights between all kinds of small metro areas. As such even routes like SF to DC only get widebodies at peak travel times like Thanksgiving and July 4th (at least those are the only times I’m able to book the United 777s for demostic flights).
Direct flights and flights more often. There’s more than enough DC-SF traffic to fill a couple of 777s a day, but people would rather have six 737s or A320s with a wider variety of departure times to choose from.
I personally wouldn't. I need an early and a late flight. The driver for all the departure times is, again, efficiency and money.
If you had 777 flights from DC to SF and SF to DC at 6:00AM and 6:00PM, I'd be content, and I think you would satisfy most needs if everyone could fit on those flights. But then you have a 777 idle for 16 hours a day.
If, instead, you had CRJ200s (that can't handle the morning and evening rush) running all day as fast as you can turn them around, they're never idle.
I guess the final point is that people vote with their wallets and fly on the airline with the cheaper CRJ200 tickets...but I wish it wasn't that way.
You need an early flight and a late flight. Bob needs flights in the middle of the day. Jane prefers mid afternoon. Any given individual only needs one flight at one time, but passengers as a whole want options.
You'll be a fan of the new midmarket airplane Boeing is planning at the moment then.
It's really hard to think of an ideal time that Boeing could reasonably have done a clean sheet 737. They're constrained in how many programs they can run at a time. After the 777, we had the huge 787 program which pushed boundaries a lot.
Then we run into this situation now where a clean sheet 737 was not going to sell and airlines didn't want to wait and retrain their pilots, so they would've switched to the A320 making a replacement 737 untenable at this time.
It seems Boeing would've needed to somehow go back in time and do a clean sheet 737 around the same time as the 757/767 program. Which would've been amazing if they'd done it, but the 737 was still a perfectly viable aircraft back then so how could they justify it.
I usually have less severe jetlag on the 737 MAX 9s compared to the Airbus fleet. I think it's the level at which they pressurize the cabins. In any case, like others have said, it really depends on the airline and seating configuration therein.
Also regarding the climate change, as I understand it, the MAX 9 changes were designed to _increase_ fuel efficiency.
