Type ratings, airport dimensions, etc. create legacy that puts limit to what kind of aircraft designs are economically viable.
If you could start from the scratch and design new aircraft and airports in tandem , would probably have much wider wingspans and lifting bodies. Airports would need different design to move passengers and arrange aircraft.
It's the type rating approval process that got old and caused all this.
What I haven't seen yet, and would love to see, is an explanation of why they went for this cascade of apparent band-aid solutions, instead of just adjusting the landing gear to give them more options for where to put the engines.
I'm sure everything I'm reading is an oversimplification, but, from what I have read, it sure sounds like the crux of the problem here is that they put the moment of thrust in the wrong spot.
It does appear that there is a bit of room to move the gear attachment point outward. Internal stuff might need to be relocated.
A very nice solution is to fold the landing gear as the B52 bomber does, asymmetrically with one in front of the other. Internal stuff almost certainly would need to be moved around, and then doors would be required. The doors would probably fit, unlike on the original, so that would be a nice upgrade.
Boeing did add some fancy stuff (on the 737MAX-10 only) to lengthen the gear right before lifting into the air and then unlengthen it as it gets retracted. The nice thing about this choice is that there need not be any changes to the height of airport equipment unless the fancy mechanism wasn't used for the nose gear. So that helps: food/maid truck, fuel truck, baggage truck, jetway or airstairs, etc.
Another option is to keep the aircraft low. This of course makes it much harder to increase the frontal area of the engines while keeping the aircraft with a pair of under-wing podded engines. We can imagine playing with the definition of "engine", installing units that have pairs of side-by-side turbines that can only be operated or maintained as a complete unit. We can imagine a much higher engine mounting, with some of the bypass air flowing over the top of the wing. We can imagine moving the engines outward to give more clearance due to wing shape, at the cost of being less-capable of crosswind landings and being more difficult to fly straight when an engine is out.
Or they could just do a clean new design.
They made the ground clearance as small as possible, because 737 engineers assumed that people have to walk stairs to the ground level to enter and exit the plane. The luggage and serving of the plane was also done by hand without lifters at that time. This unfortunate choice led to engine placement that increased fuel consumption they tried to fix.
Newly designed aircraft would have better handling without these fixes.
If you want to call that "forcing" is a matter of taste, but it's certainly a very strong and involuntary incentive.
They’ve released newer model planes that have gone through the review process fine, correct?
> In 2006, Boeing started considering the replacement of the 737 with a "clean-sheet" design that could follow the Boeing 787 Dreamliner. In June 2010, a decision on this replacement was postponed into 2011.
> On December 1, 2010, Boeing's competitor, Airbus, launched the Airbus A320neo family to improve fuel burn and operating efficiency with new engines: the CFM International LEAP and Pratt & Whitney PW1000G. In February 2011, Boeing's CEO Jim McNerney maintained "We're going to do a new airplane." At the March 2011 ISTAT conference, BCA President James Albaugh was not sure about a 737 re-engine, like Boeing CFO James A. Bell stated at the JP Morgan Aviation, Transportation and Defense conference the same month. The A320neo gathered 667 commitments at the June 2011 Paris Air Show for a backlog of 1,029 units since its launch, setting an order record for a new commercial airliner.
> On July 20, 2011, American Airlines announced an order for 460 narrowbody jets including 130 A320ceos and 130 A320neos, and intended to order 100 re-engined 737s with CFM LEAPs, pending Boeing confirmation. The order broke Boeing's monopoly with the airline and forced Boeing into a re-engined 737.
Boeing has hinted several times that they want to look at a Blended Wing Body (BWB) design for the next generation of planes. That time may be now.
Safety requirements have evolved massively since then, but if you keep making the same engine with modest changes it can grandfathered. Kind of makes you wonder if grandfathering should have a limit (e.g. 50 years?).
The craziest aspect of the Soyuz that makes it obvious how legacy it is is how its engines are ignited: https://www.popularmechanics.com/space/rockets/a19966/russia...
You literally put something not too dissimilar from a wooden chair directly beneath the rocket nozzles, then set it on fire right before launch. When the rocket's engines start up, the fuel is ignited by the fire from the burning wood, and combustion begins. Now that's legacy. It's also reliable enough that they've never had to redesign it.
Yeah, the bulk of the device, and its combustible material, is made of wood. But it's also got two igniters (for redundancy) and a sensor for ensuring that the device has successfully ignited. Some engineering thought went into this. Comparing it to putting a burning piece of furniture under the rocket nozzles makes the whole design sound a lot more jerry-rigged than it really is.
“This setup is not as simple as a regular match, but it is surprisingly reliable and has worked for six decades on hundreds of rockets”
So why attempt to fix such a safety critical thing?
I'm no rocket engineer, but my guess would be that, if you're shutting down an engine at that stage in the flight, your only realistic options are going to be redirecting fuel to the remaining engines for a longer burn, or cutting all engines and activating the launch escape system. I can't imagine there's any practical reason to plan on shutting down and re-igniting engines during the first stage of a launch, and I also can't imagine trying to decide whether an engine is safe to re-light during the few seconds you'll have between when you executed the emergency shutdown and when it's time to jettison the first stage entirely.
That's not grandfathering. Grandfathering is "This engine was built before we made the law, so you can keep using it until it breaks."; what you're describing is just blatant selective enforcement.
It's similar to how I can continue to drive an old car that doesn't have ABS, since ABS wasn't required or invented when the car was built.
The difference of course is with cars we update the rules and apply them to all new cars as of a certain date. We don't allow someone to keep making cars using a design from 1967, at least not without including current safety features.
The reason it exists is otherwise the FAA could release a new requirement that would halt a pre-existing production line that didn't meet it.
> Because part 135 operators will have limited ETOPS operations, the FAA has decided to grandfather from today's rule all part 135 airplanes manufactured up to 8 years from the effective date of the rule. For purposes of airworthiness requirements, part 135 operators may use these airplanes in ETOPS without certification under § 25.1535. This is a change from the NPRM, which proposed grandfathering only those airplanes that were on an operator's operations specifications up to 8 years after the rule. Under the NPRM, they would then have had to remain on the operator's operations specifications to continue to operate ETOPS.
> b. This Advisory Circular (AC) provides guidance to affected U.S. operators that operate aircraft outside the United States with aircraft that were never required to be noise certified. If you have such an aircraft, this AC outlines the noise certification requirement dates so you can confirm that your aircraft indeed pre-dates the requirements and should be considered acceptable. We use the term “grandfathered” for these aircraft. We strongly recommend operators of such aircraft to use the FAA form in Appendix 1 that includes a grandfather clause.
> These seats should provide adequate vision to the pilot's panel and forward windows in visual system models. "Grandfather rights" prevail on previously approved simulators; however, efforts should be made to improve surveillance visibility. These observer seats need not represent the aircraft seats.
0: or not-technically-criminally if they planned ahead well enough.
Which is both fair and appropriate and proportional if it means that people don't die.
Imagine if all of the cloud computing data centers ran off legacy IBM mainframes -- then it'd be a more akin situation.
These comparisons are off a bit, though, because development lifecycles in airplanes are longer than for computer hardware.
It’s not a perfect anology, but probably better than systems that aren’t really changing much anymore.
Practically speaking, for the flavors of UNIX like systems most will work with this is equivalent to streams of 8 bit, clean-transferred, characters.
Any other kind of transfer system that you might want to build can be built on top of that. This interlinking design is the minimum viable product, and also the lowest level one. Comparing to a more recent design, such as PowerShell, transfer of objects limits flexibility and requires more shared infrastructure.
The key difference here, I think, is that there haven't been radical new improvements in firearms. You can clearly point out where the faults in, say, legacy airplanes lie, but guns (at least in civilian uses) haven't changed as much. Now, granted, for military uses, the modern assault rifle is a far cry from the aforementioned guns.
Just looking at the diagrams in that page, I doubt that measurements were defined with a 0.001 inch accuracy in 1921.
The technology was pretty mature in 1921, there were a few rounds of refinement before that. Machinists definitely talked about "one thou" back then. The same M2s which fire these things have been in production for over 80 years. I'm sure there have been small tweaks, special versions, etc, but basic compatibility has remained.
I keep reading comments that it was just corporate greed or just regulatory capture or Boeing should’ve just built a new plane. But I suspect it’s not that simple, and that there are lessons to be learned beyond what the crash investigations uncover.
For example, from reading the Wikipedia on the 737 Max it sounds like Boeing was pressured by the airlines into producing the Max after Airbus was able to ship a more fuel efficient 320.
Usually you expect competition to lead to better products so it would be somewhat ironic if the competition from Airbus is what forced Boeing’s hand on producing the Max. Without that pressure maybe Boeing could have told the airlines to back off while it produced a new design.
The much smaller Embraer 195 is vastly more comfortable than the 737 because it is shaped according to the passengers.
A clean sheet design for the 737 would have a big positive impact for the industry. Today it is another reason to take the bus.
The problem wasn't just the ground clearance. the problem was that aerodynamically had issues (not so well balanced probably). So when they were trying to fix "this" something else was breaking and so on. That's why they introduced this MCAS software in the first place. It wasn't some new fancy tech but it was just a system to help with the bad 737's aerodynamics.
This creeping change must be really hard to regulate right. A terrible new design you could refuse to certify, but a terrible one which is only a few percent worse than the one your predecessor certified a decade ago... it would take a lot of confidence to say no.
This has to be THE MOST Stupidest decision i have ever read about.. either extend the landing gear or start from scratch.
Aeroplanes should be naturally neutral Longitudinally and also have longitudinal static
stability it should never require complex control systems to achieve any of this.
It should never have passed certification.
Or have you ever flown a Cessna 152 or 172? They have the same tendency to pitch up strongly when power is advanced at low speeds. This is probably the most common training aircraft in the world, and yet have a behavior that may cause them to stall at exactly the most inopportune time. And they're flown by students, not airline transport pilots!
The 737 MAX does not require the MCAS. The pilots could be trained to expect and handle this characteristic. (And they are, as it is apparently, to a lesser degree, present on all 737 models.)
The big problem lies in the design of the MCAS system and the fact that it was decided to rely on this and not train pilots on the new behavior.
just because "a pilot should be able to handle it" is not acceptable.
Aeroplanes traditionally are designed with as much passive self correcting features as possible for safety.
When a plane has a real emergency the less a pilot has to actively deal with the more likely people are going to come out alive.
The evidence is clear that this was a huge mistake.. many people have already died.
Either that or ground the plane permanently for being poorly designed and unsafe with any amount of training.
If the FAA does anything else, it will harm my faith in the organization, which is already at a recent low.
NB: Jet pilot, not 737 pilot.
What's not clear to me is how much worse the characteristics of the MAX are compared to the NG or earlier 737s? Would it really be unsafe to fly without the MCAS, or was this just the route Boeing took to avoid having to retrain pilots?
I agree with you that pilot training doesn't seem to be a plausible answer given that the Lion Air crash was world news, resulting in retraining, and yet that wasn't enough.
It's that pilot training wasn't done that absolutely needed to have been.
A three page if even that description of the system, and it's inputs/outputs/controls should have been sufficient for a pilot to be able to build up a mental model to deal with a faulty AoA sensor, and modify their piloting technique to stay within a more conservative maneuvering envelope while operating the plane.
Whether that would have been sufficient to prevent both disasters I don't know, but it sure seems like it would be a small trade off that even in the absence of any other system hardening could have made the difference between no survivors, and an emergency landing.
> One hopes that the pilot a) knows and b) remembers to turn off the autopilot when the emergency starts.
This is where training kicks in. After hitting the scenario 10 times in the simulator, the pilot doesn't remember; they _do_.
The trouble with that is the pilot's controls simply crack open a valve, and hydraulics do the rest, meaning the pilot gets no feedback via forces on the control column. He'll "overcontrol" the aircraft leading to a crash. The solution is the addition of a "feel computer" which pushes back on the stick making the airplane feel like direct control. Safe flying relies on the feel computer working properly.
Also, the travel of the control surfaces is automatically reduced as speed goes up, because full travel at high speeds will literally tear the airplane apart.
So right there are two flight critical computer systems on jets, and modern air travel would not be possible without them. Each produces an illusion to the pilot.
However I'm referring to a computer literally trying to hide a stall that occurs when you pitch the nose up by producing an inverse signal out of thin air that has no input from the pilot. Why wasn't this needed before the max moniker was added to the plane?
Seriously, build the plane so that this doesn't happen. Don't create some MCAS system to hide it.
I'm saying similar to the older design make the aerodynamic shape good enough so that it won't hit that stall when the plane is flying at that same configuration. I'm also saying that the control system should only magnify or reduce the signals the pilot sends to the control surfaces rather than actually sending it's own override signals itself. That's it... pure and simple.
What about fly-by-wire? Many aerodynamic controls are assisted by avionics, and have been for decades. The MCAS system is not fundamentally different. The intent of the system was to put the plane where the pilot wanted intended it to go, similar to how a fly-by-wire system will keep a plane flying straight if a pilot doesn't touch the yoke.
The problem seems to be that the MCAS system breaks under certain conditions, however the fundamental idea is sound. Planes have been doing similar control adjustments for decades.
The 737 MAX was made more aerodynamically unstable then the original 737. A partial control system was put in place to hide this instability should the pilot maneuver the plane into the configuration that will trigger a stall. It's an entirely different situation than the jet plane above.
Think of it like a bandaid to cover up a problem. I'm saying don't use bandaids. Design the plane correctly from the ground up.
I wasn't talking about military craft, I was referring to commercial aircraft that also have fly-by-wire capabilities, of which there are plenty of examples. The MCAS is not fundamentally different from these other existing systems.
The MCAS is fundamentally different in that it is a partial FBW system that they tacked on on top of an existing control scheme that is not FBW.
It's a random partial FBW component grafted onto something that's completely different. Sort of like a mod chip in a console. It's a hack. To drive home the exact opposite of what you said: "MCAS is abnormal and fundamentally different from many existing systems."
That way, an elevator should always have more authority than the trim tab, and be able to overpower it if it fails.
On other hand, independent trim tabs can work as reserve control surfaces if hydraulics fail.
The same design thinking is behind having engine reverse locks being physical parts, separately powered, and operated independently of electronic engine controls: a hard lock will always be able to overpower haywire electronics.
Same with emergency chassis deployment system on smaller planes, they are often designed to be able to physically disconnect/overpower motors that pull chassis, or chassis cowers if they jam or electronics bugs out.
However, only the 737 MAX has MCAS, and MCAS doesn't take airspeed into account. An appropriate corrective action for a low airspeed stall, will be way too aggressive for a high airspeed stall (a rare event, suggests overly aggressive dive recovery leading to a stall). And designers + regulators assumed that pilots would treat such behavior the same as an ordinary runaway trim incident, but does it seem ordinary or is it a shockingly bad overcorrection?
We've seen many times the scenario where pilots become so surprised at a particular situation that their rational ability to work through the problem can be compromised. Yes, transport pilots are substantially trained to avoid such a compromise, but problems at low altitude combined with the lack of a consistently positive rate of climb is an urgent situation. Pilots are hyper aware that recovery from either a dive or stall consumes a huge amount of altitude, which you simply don't have at low altitude. That itself could delay proper decision making: i.e. automation has betrayed us for unknown reasons, disable it now.
With MCAS disabled, what's the 737 MAX stall behavior like? Is it meaningfully easier to unwittingly get into a stall?
They could have prevented this issue by slightly increasing the tailplane size to restore stability margin, but they didn't presumably for development cost and fuel efficiency reasons.
That thinking remind me of people who try to economise on few microns of plastic we see in electronics OEM industry. Pro managers trying to shave microns from casing, ending up with multimillion dollar recalls, and that for savings not even amounting to few snickers bars.
Then the engines could have remained in the same position. I am sure most airports could handle a taller airplane.
Honestly if the accidents did not happen we’d be calling them geniuses. After all, that’s why the 737 is the best selling plane ever.
Even with the extension it’s not as tall as the 757 or A320 series.
I don't think they have to remember all of them. Pilots rely heavily on checklists to make sure procedures are followed correctly and few mistakes are made.
But if there's already an existing type out there that's a better fit, why not just use that?
Plus, the 757 has some features on it that make it more of a longer range, transcontinental jet than the 737. That makes it more expensive. If all you're using it for is regional air service (the existing mission of the 737), then it's too expensive for the job. The 737 is the Honda Civic of the skies; the 757 is more like a (insert more expensive car model here).
There's not many things they could've changed about the existing design without it being enough unlike the existing design to effectively count as a new aircraft (logistically if not certification-wise). They could move the engines, but they couldn't change the ground clearance.
However the MAX-10 required a telescoping landing gear to achieve that so I'm assuming the real reason to not do so earlier was cost to design, cost to manufacture and weight.
Also the MAX 10 hasn’t been built or certified yet, I’m sure there will be a lot more scrutiny when that does happen.
The Cold War started in the second half of the 1940's, so I rather doubt that is true.
Basically, the US has taken the view that any regulation should be strongly supported by facts and evidence, while many other countries are more willing to regulate on a precautionary basis, before all the results are in.
Two planes of the same model crashing of is a statistical anomaly. Science is the correlation of hypothesis with statistical evidence. If I made a hypothesis saying that something is wrong with the 737 max then two 737 planes crashing is valid supporting evidence. Therefore, the decision to regulate is scientific.
The decision to not regulate and claim that there is no scientific evidence when their clearly is... is more likely to be a cover story to protect big businesses then an actual decision made to support your safety.