10 ms·

A 50-year-old design came back to haunt Boeing with its troubled 737 Max jet

128 points by eplanit 8y ago

InTheArena 8y ago
Really it's worse then that. The 737Max is a good example of technical debt. The plane more or less is the same fuselage as a Boeing 707 (with material modernized). Boeing went back to the well one time too many instead of doing a cleanroom design for it's narrow-body fleet. 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.
- CydeWeys 8y ago
  It's hard to think of many other legacy systems that have been around since at least the 60s like the 737 MAX has. The NYC subway system is one that immediately comes to mind.
  - tyingq 8y ago
    The IBM mainframe would be a good example in our world, though the really strong tie is probably MVS and TPF from the 70's, rather than the 60's.
    - CydeWeys 8y ago
      That's much more 'legacy' than the 737 is, though. The 737 MAX was projected to be the best selling airplane of the modern era of aviation, and it's a legacy system. Yeah, there's still some old IBM mainframes lingering on in some places, but they're not remotely close to having the same market dominance. 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.
      - tyingq 8y ago
        The parent didn't have a "market dominant" qualifier...
      - bluejekyll 8y ago
        In our world the Unix operating system might be the best analogy. It’s an old design that’s been modernized in different ways, but ultimately has the same general interface (libc) that is still essentially the same. It’s not a perfect anology, but probably better than systems that aren’t really changing much anymore.
        jdsully 8y ago
        Unix is a very apt example. We wouldn’t be piping text around if it were designed today - but it does work decently well.
        mjevans 8y ago
        It's not text, it's opaque character streams. (C 'char' type) 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.
        flo123456 8y ago
        Or Intel‘s x86 architecture.
    - kens 8y ago
      Yes, the IBM System/360's instruction set is still a part of IBM's current mainframes, so customers can still run their 1964 programs. (Does anyone know when IBM dropped backwards compatibility for their 1950s architectures? They provided emulation for 1401 and 709 systems for a long, long time.) It will be interesting to see if the 360 or x86 instruction set lasts longer.
  - sitkack 8y ago
    SABRE dates from the 50s.
    - tyingq 8y ago
      Yes, but if you draw the line at where what they had resembled what they offer today, it's around the 1970's.
  - Someone1234 8y ago
    The engines on many light single-engine aircraft (e.g. Lycoming O-360). While variants and modest improvements have been made, it is still the same 1950s engine at the core. 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?).
    - CydeWeys 8y ago
      The Soyuz definitely counts too. It was designed in the 60s and hasn't changed too much since then. 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-actually-lights-it-rockets-with-a-giant-match/ 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.
      - bunderbunder 8y ago
        "Wooden chair" seems like a rather drastic oversimplification. 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.
        Xylakant 8y ago
        Notably, the ignition device, while seemingly low tech, works pretty much without flaws and fails safely. “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?
  - hoorayimhelping 8y ago
    American Delta rockets and Russian Soyuz rockets come to mind.
  - theoh 8y ago
    The T-38 first flew in 1959.
  - vpribish 8y ago
    do you use banks?
  - iguy 8y ago
    Lots of ammunition is really old, e.g. 1921 (but really a slight tweak of a 1906 design): https://en.wikipedia.org/wiki/.50_BMG https://en.wikipedia.org/wiki/.50_BMG
    - user5994461 8y ago
      That's inaccurate at best. The shell size is mostly unchanged. The powder inside, the materials and the manufacturing have progressed. Just looking at the diagrams in that page, I doubt that measurements were defined with a 0.001 inch accuracy in 1921.
      - iguy 8y ago
        Well, not an expert, but have you got any information here? 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.
      - Treblemaker 8y ago
        Vernier calipers capable of measuring 0.001 inch were available in 1851. Agree on your first point, however.
      - CydeWeys 8y ago
        The powder really isn't that different. The max pressure allowable is part of the cartridge specification, which hasn't changed since the original design. Otherwise you'd have newer ammunition blowing up older guns, which clearly would be unacceptable. You can take modern .30-06 ammo, which is still a very popular hunting cartridge, and fire it in an M1903 Springfield with no issues.
    - CydeWeys 8y ago
      Lots of good examples in firearms. Forget just ammunition, there's old firearm designs that regularly see use today. Some examples would be the 1911 pistol, or the M2 Browning machine gun (1918). And there's entire classes of firearms that are essentially unchanged from that period, like bolt-action rifles, most of which use a Mauser action which was designed in 1895. 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.
  - tim333 8y ago
    The B52 since 1955.
    - lutorm 8y ago
      And the C-130. An extremely successful aircraft.
- Nomentatus 8y ago
  Went back to the well for marketing reasons. Keeping the shape, but only the shape, so they could use the 737 name.
  - Nomentatus 8y ago
    I see there are those who agree with the FAA's decision that the MCAS didn't represent a change worthy of mention, nor new materials, new factories... "nothing to see here folks." I think by now it's obvious that was a "puzzling" decision.
danny8000 8y ago
I wonder why Boeing didn’t they design new, longer landing gear instead of moving the engines forward? Then the engines could have remained in the same position. I am sure most airports could handle a taller airplane.
- rfugger 8y ago
  I think I read that longer landing gear wouldn't fit into the fuselage without major reconfiguration.
  - marcinzm 8y ago
    The MAX-10 got around that by having a telescoping landing gear and was able to get 10 inches more as a result.
- Moto7451 8y ago
  Not a direct answer, but what you’re more or less asking is “why did they not modernize the 757 instead?” The answer is type ratings. Pilots can fly certain classes of planes based on common training. I.E. the 757 and 767 are common enough you can be trained for both at the same time. The issue with changing geometry of the 737 is you have to then retrain pilots against a new type instead of letting them take an orientation course on the new plane. 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.
  - podgib 8y ago
    Not really - they definitely could have extended the landing gear of the 737, as evidenced by the fact that they did exactly that for the 737 MAX 10. To handle the extra length they added telescoping landing gear that are about 10 inches longer than on the other variants
    - Moto7451 8y ago
      Lengthening the landings gear did nothing to change the engine placement. It was done to allow for type commonality. https://www.geekwire.com/2018/boeing-737-max-10-landing-gear/ https://www.geekwire.com/2018/boeing-737-max-10-landing-gear... Even with the extension it’s not as tall as the 757 or A320 series.
baybal2 8y ago
And one more thing - trim tabs should be separate airfoils, not an electronically set setting exactly for the purpose of reliability. 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.
- CarVac 8y ago
  Trim would never be a separate airfoil because that would be horrendous for efficiency. Instead they have an all-moving tailplane. 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.
  - baybal2 8y ago
    Are you really sure that it will be "horrendous?" 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.
    - CydeWeys 8y ago
      You're adding an entire new system. That's more wiring, more programming, more hydraulics, more moving parts, etc. It's far from trivial.
      - baybal2 8y ago
        Far from trivial, but it was done in the past nevertheless. All things above were going away one after another, and replaced with often ineffectual electronic safeguards.
etep 8y ago
It's not nice that so many writers parrot that the solution is "more pilot training." Under the hypothesis that there needs to be a solution (one that I think is correct), then the answer of more training amounts to mere hope. One hopes that the pilot a) knows and b) remembers to turn off the autopilot when the emergency starts.
- cjbprime 8y ago
  We're told that MCAS only activates with the autopilot already off. 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.
  - etep 8y ago
    Thank you for the insight! Just for clarity, I'm using "autopilot" as a catch-all term that refers the automated systems that plausibly seem to have caused these crashes.
    - alexbecker 8y ago
      ...which is a pretty confusing thing to do, given that there are multiple such systems, one of which is conventionally called "autopilot".
- SomeHacker44 8y ago
  Pilots can fly planes with unusual characteristics when properly trained. That is the point of the type rating. I feel the 737 MAX needs its own type certificate distinct from the rest of the 737s and that should solve the problem, since the MAX has very different flight characteristics in certain situations. 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.
  - lutorm 8y ago
nabla9 8y ago
Boeing want's to keep the type rating and rest of the infrastructure, but the airframe is getting old. They made a small tweak, moved engines forward, and gained significant fuel savings. The tweak caused instability. The fixed it with automation that introduced complication. 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.
- lstodd 8y ago
  The airframe isn't getting old. In fact there's nothing left of the old airframe but the general shape of the windshields. It's the type rating approval process that got old and caused all this.
  - nabla9 8y ago
    Many design choices still exist. Some design constraints were irrelevant already when the plane was introduced, yet they still exist and haunt the plane. 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.
  - JorgeGT 8y ago
    The 737 is a great example of a Ship of Theseus, years of small changes have left barely anything of the original besides the name... and the type certificate.
    - bunderbunder 8y ago
      And, apparently, sitting very low on the tarmac. 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.
mrpippy 8y ago
For those who might be interested: the 737 type certificate data sheet. Revised 64 times since 1967 and covering original, Classic, NG, and MAX. http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/179cdacd213801658625832a006b2e37/$FILE/A16WE_Rev_64.pdf http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeMod...
burtonator 8y ago
My family would have flown on a 737 Max this morning. Flight was cancelled. The FAA was literally the last regulatory org to ground the 737 Max... I'm livid that corruption and bias put my family at risk!
- crimsonalucard 8y ago
  Yeah. It is strange that they were the last regulatory org to do so. . In America basically every governmental body is in the pocket of big business.
  - ardy42 8y ago
    This is an interesting take on it: https://www.nytimes.com/2019/03/15/opinion/federal-aviation-administration-boeing.html https://www.nytimes.com/2019/03/15/opinion/federal-aviation-.... 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.
    - crimsonalucard 8y ago
      A speculative opinion piece. Here is another one: https://www.vox.com/policy-and-politics/2019/3/13/18263719/boeing-ceo-dennis-muilenburg-trump-tweet-call https://www.vox.com/policy-and-politics/2019/3/13/18263719/b... 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.
- ams6110 8y ago
  N.B. no American carriers have crashed a MAX, and they are flying quite a few of them.
PaulHoule 8y ago
The 737 is not uncomfortable because it is narrow but because it is not tall enough. The circular fuselage makes it so. 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.
gargalatas 8y ago
"The change, however, affected the plane’s aerodynamics. Boeing discovered the new position of the engines increased the lift of the aircraft, creating a tendency for the nose to pitch up." 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.
- iguy 8y ago
  Right, but it sound like the aerodynamics have been deteriorating model-by-model, as they move away from the original design. 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.
basicplus2 8y ago
<Boeing added larger, more powerful engines, but that required it to reposition them to maintain ground clearance. As a result, the 737 can pitch up under certain circumstances.> 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. https://en.m.wikipedia.org/wiki/Longitudinal_static_stability https://en.m.wikipedia.org/wiki/Longitudinal_static_stabilit...
- lutorm 8y ago
  "Under certain circumstances" is, as I understand it, close to stall. Many planes have less-than-desired stall characteristics. The tendency of T-tail planes to go into an unrecoverable deep stall comes to mind. 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.
  - basicplus2 8y ago
    putting and engine on the wing in an undesirable position because of the height of the landing gear is stupid.. 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.
crimsonalucard 8y ago
They should have a philosophy of building aerodynamically stable aircraft rather than relying on software and sensors to produce an illusion of stability.
- WalterBright 8y ago
  Consider that before WW2, pilots had direct connection between the control and moving the surface. After WW2, planes got too big and heavy for that, and hydraulic boost was added. Starting with the 747, where it is not credible a pilot could control it with muscle, the switch was made to fully powered surfaces. 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.
  - crimsonalucard 8y ago
    Right, this makes sense. The system you describe magnifies or reduces the signals going back and forth between the pilot and the control surfaces. It can be modelled linearly and done with an analog system. 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.
    - WalterBright 8y ago
      MCAS was there to prevent a stall, not hide it. All airplanes will stall under varying circumstances. Much of pilot training goes towards avoiding and recovering from stalls, but they still result in crashes.
upofadown 8y ago
The calls for more and better training make me wonder why we don't just train for the relatively rare over pitch characteristic that the MCAS system is intended to prevent. If we can't actually train for that then why are we suggesting that the solution is just being quick to turn the system off? What level of unreliability is required to make it better to just never turn it on?
js2 8y ago
I would be interested in an organizational investigation of Boeing, the FAA and the airlines similar to the investigation of NASA after the Challenger disaster. 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.
- pducks32 8y ago
  I’m no airplane expert but I find the trend lines of the industry interesting and one trend has been how fuel prices and long lead times on fuel efficiency has lead to formerly continental planes now flying intercontinental. AirBus has really done this well and airlines love to be able to reuse resources. With the MAX there is a sense that airline execs are spooked by a new plane since it requires a ton of new training and maintenance outfitting. So Boeing, possibly smartly, tried to create what these airlines would pay for (a fuel efficient airplane) that would marketable be super similar to a very popular plane. But this lead to rushing the process and making too many affordances and hiding the differences from airlines and training material for fear of spooking business execs worried about cost.
Invictus0 8y ago
Does anyone know why Tunisia refused to work with the FAA?
woodandsteel 8y ago
"First introduced in West Germany as a short-hop commuter jet in the early Cold War" The Cold War started in the second half of the 1940's, so I rather doubt that is true.
cmurf 8y ago
Any design will have consequences, and is thus relevant. But changing it has as much of a consequence as not changing it. Example: Airbus design has "stick" type yokes that are not linked together, and are out of the field of view. If one pilot is using improper inputs, the other pilot won't know. Boeing planes have mechanically connected yokes, both pilots are aware of flight control inputs. Is one a better design than the other? I suggest it's the wrong question, the right question is, what are the consequences of the design on cockpit communication, management, and training and can we meet the ensuing requirements?

128 points by eplanit 8y ago

Really it's worse then that. The 737Max is a good example of technical debt. The plane more or less is the same fuselage as a Boeing 707 (with material modernized). Boeing went back to the well one time too many instead of doing a cleanroom design for it's narrow-body fleet. 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.

CydeWeys 8y ago
It's hard to think of many other legacy systems that have been around since at least the 60s like the 737 MAX has. The NYC subway system is one that immediately comes to mind.
- tyingq 8y ago
  The IBM mainframe would be a good example in our world, though the really strong tie is probably MVS and TPF from the 70's, rather than the 60's.
  - CydeWeys 8y ago
    That's much more 'legacy' than the 737 is, though. The 737 MAX was projected to be the best selling airplane of the modern era of aviation, and it's a legacy system. Yeah, there's still some old IBM mainframes lingering on in some places, but they're not remotely close to having the same market dominance. 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.
    - tyingq 8y ago
      The parent didn't have a "market dominant" qualifier...
    - bluejekyll 8y ago
      In our world the Unix operating system might be the best analogy. It’s an old design that’s been modernized in different ways, but ultimately has the same general interface (libc) that is still essentially the same. It’s not a perfect anology, but probably better than systems that aren’t really changing much anymore.
      - jdsully 8y ago
        Unix is a very apt example. We wouldn’t be piping text around if it were designed today - but it does work decently well.
        mjevans 8y ago
        It's not text, it's opaque character streams. (C 'char' type) 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.
      - flo123456 8y ago
        Or Intel‘s x86 architecture.
  - kens 8y ago
    Yes, the IBM System/360's instruction set is still a part of IBM's current mainframes, so customers can still run their 1964 programs. (Does anyone know when IBM dropped backwards compatibility for their 1950s architectures? They provided emulation for 1401 and 709 systems for a long, long time.) It will be interesting to see if the 360 or x86 instruction set lasts longer.
- sitkack 8y ago
  SABRE dates from the 50s.
  - tyingq 8y ago
    Yes, but if you draw the line at where what they had resembled what they offer today, it's around the 1970's.
- Someone1234 8y ago
  The engines on many light single-engine aircraft (e.g. Lycoming O-360). While variants and modest improvements have been made, it is still the same 1950s engine at the core. 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?).
  - CydeWeys 8y ago
    The Soyuz definitely counts too. It was designed in the 60s and hasn't changed too much since then. 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-actually-lights-it-rockets-with-a-giant-match/ 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.
    - bunderbunder 8y ago
      "Wooden chair" seems like a rather drastic oversimplification. 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.
      - Xylakant 8y ago
        Notably, the ignition device, while seemingly low tech, works pretty much without flaws and fails safely. “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?
- hoorayimhelping 8y ago
  American Delta rockets and Russian Soyuz rockets come to mind.
- theoh 8y ago
  The T-38 first flew in 1959.
- vpribish 8y ago
  do you use banks?
- iguy 8y ago
  Lots of ammunition is really old, e.g. 1921 (but really a slight tweak of a 1906 design): https://en.wikipedia.org/wiki/.50_BMG https://en.wikipedia.org/wiki/.50_BMG
  - user5994461 8y ago
    That's inaccurate at best. The shell size is mostly unchanged. The powder inside, the materials and the manufacturing have progressed. Just looking at the diagrams in that page, I doubt that measurements were defined with a 0.001 inch accuracy in 1921.
    - iguy 8y ago
      Well, not an expert, but have you got any information here? 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.
    - Treblemaker 8y ago
      Vernier calipers capable of measuring 0.001 inch were available in 1851. Agree on your first point, however.
    - CydeWeys 8y ago
      The powder really isn't that different. The max pressure allowable is part of the cartridge specification, which hasn't changed since the original design. Otherwise you'd have newer ammunition blowing up older guns, which clearly would be unacceptable. You can take modern .30-06 ammo, which is still a very popular hunting cartridge, and fire it in an M1903 Springfield with no issues.
  - CydeWeys 8y ago
    Lots of good examples in firearms. Forget just ammunition, there's old firearm designs that regularly see use today. Some examples would be the 1911 pistol, or the M2 Browning machine gun (1918). And there's entire classes of firearms that are essentially unchanged from that period, like bolt-action rifles, most of which use a Mauser action which was designed in 1895. 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.
- tim333 8y ago
  The B52 since 1955.
  - lutorm 8y ago
    And the C-130. An extremely successful aircraft.
Nomentatus 8y ago
Went back to the well for marketing reasons. Keeping the shape, but only the shape, so they could use the 737 name.
- Nomentatus 8y ago
  I see there are those who agree with the FAA's decision that the MCAS didn't represent a change worthy of mention, nor new materials, new factories... "nothing to see here folks." I think by now it's obvious that was a "puzzling" decision.

danny8000 8y ago

I wonder why Boeing didn’t they design new, longer landing gear instead of moving the engines forward? Then the engines could have remained in the same position. I am sure most airports could handle a taller airplane.

rfugger 8y ago
I think I read that longer landing gear wouldn't fit into the fuselage without major reconfiguration.
- marcinzm 8y ago
  The MAX-10 got around that by having a telescoping landing gear and was able to get 10 inches more as a result.
Moto7451 8y ago
Not a direct answer, but what you’re more or less asking is “why did they not modernize the 757 instead?” The answer is type ratings. Pilots can fly certain classes of planes based on common training. I.E. the 757 and 767 are common enough you can be trained for both at the same time. The issue with changing geometry of the 737 is you have to then retrain pilots against a new type instead of letting them take an orientation course on the new plane. 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.
- podgib 8y ago
  Not really - they definitely could have extended the landing gear of the 737, as evidenced by the fact that they did exactly that for the 737 MAX 10. To handle the extra length they added telescoping landing gear that are about 10 inches longer than on the other variants
  - Moto7451 8y ago
    Lengthening the landings gear did nothing to change the engine placement. It was done to allow for type commonality. https://www.geekwire.com/2018/boeing-737-max-10-landing-gear/ https://www.geekwire.com/2018/boeing-737-max-10-landing-gear... Even with the extension it’s not as tall as the 757 or A320 series.

baybal2 8y ago

And one more thing - trim tabs should be separate airfoils, not an electronically set setting exactly for the purpose of reliability. 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.

CarVac 8y ago
Trim would never be a separate airfoil because that would be horrendous for efficiency. Instead they have an all-moving tailplane. 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.
- baybal2 8y ago
  Are you really sure that it will be "horrendous?" 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.
  - CydeWeys 8y ago
    You're adding an entire new system. That's more wiring, more programming, more hydraulics, more moving parts, etc. It's far from trivial.
    - baybal2 8y ago
      Far from trivial, but it was done in the past nevertheless. All things above were going away one after another, and replaced with often ineffectual electronic safeguards.

etep 8y ago

It's not nice that so many writers parrot that the solution is "more pilot training." Under the hypothesis that there needs to be a solution (one that I think is correct), then the answer of more training amounts to mere hope. One hopes that the pilot a) knows and b) remembers to turn off the autopilot when the emergency starts.

cjbprime 8y ago
We're told that MCAS only activates with the autopilot already off. 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.
- etep 8y ago
  Thank you for the insight! Just for clarity, I'm using "autopilot" as a catch-all term that refers the automated systems that plausibly seem to have caused these crashes.
  - alexbecker 8y ago
    ...which is a pretty confusing thing to do, given that there are multiple such systems, one of which is conventionally called "autopilot".
SomeHacker44 8y ago
Pilots can fly planes with unusual characteristics when properly trained. That is the point of the type rating. I feel the 737 MAX needs its own type certificate distinct from the rest of the 737s and that should solve the problem, since the MAX has very different flight characteristics in certain situations. 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.
- lutorm 8y ago

nabla9 8y ago

Boeing want's to keep the type rating and rest of the infrastructure, but the airframe is getting old. They made a small tweak, moved engines forward, and gained significant fuel savings. The tweak caused instability. The fixed it with automation that introduced complication. 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.

lstodd 8y ago
The airframe isn't getting old. In fact there's nothing left of the old airframe but the general shape of the windshields. It's the type rating approval process that got old and caused all this.
- nabla9 8y ago
  Many design choices still exist. Some design constraints were irrelevant already when the plane was introduced, yet they still exist and haunt the plane. 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.
- JorgeGT 8y ago
  The 737 is a great example of a Ship of Theseus, years of small changes have left barely anything of the original besides the name... and the type certificate.
  - bunderbunder 8y ago
    And, apparently, sitting very low on the tarmac. 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.

mrpippy 8y ago

For those who might be interested: the 737 type certificate data sheet. Revised 64 times since 1967 and covering original, Classic, NG, and MAX. http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/179cdacd213801658625832a006b2e37/$FILE/A16WE_Rev_64.pdf http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeMod...

burtonator 8y ago

My family would have flown on a 737 Max this morning. Flight was cancelled. The FAA was literally the last regulatory org to ground the 737 Max... I'm livid that corruption and bias put my family at risk!

crimsonalucard 8y ago
Yeah. It is strange that they were the last regulatory org to do so. . In America basically every governmental body is in the pocket of big business.
- ardy42 8y ago
  This is an interesting take on it: https://www.nytimes.com/2019/03/15/opinion/federal-aviation-administration-boeing.html https://www.nytimes.com/2019/03/15/opinion/federal-aviation-.... 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.
  - crimsonalucard 8y ago
    A speculative opinion piece. Here is another one: https://www.vox.com/policy-and-politics/2019/3/13/18263719/boeing-ceo-dennis-muilenburg-trump-tweet-call https://www.vox.com/policy-and-politics/2019/3/13/18263719/b... 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.
ams6110 8y ago
N.B. no American carriers have crashed a MAX, and they are flying quite a few of them.

PaulHoule 8y ago

The 737 is not uncomfortable because it is narrow but because it is not tall enough. The circular fuselage makes it so. 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.

gargalatas 8y ago

"The change, however, affected the plane’s aerodynamics. Boeing discovered the new position of the engines increased the lift of the aircraft, creating a tendency for the nose to pitch up." 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.

iguy 8y ago
Right, but it sound like the aerodynamics have been deteriorating model-by-model, as they move away from the original design. 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.

basicplus2 8y ago

<Boeing added larger, more powerful engines, but that required it to reposition them to maintain ground clearance. As a result, the 737 can pitch up under certain circumstances.> 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. https://en.m.wikipedia.org/wiki/Longitudinal_static_stability https://en.m.wikipedia.org/wiki/Longitudinal_static_stabilit...

lutorm 8y ago
"Under certain circumstances" is, as I understand it, close to stall. Many planes have less-than-desired stall characteristics. The tendency of T-tail planes to go into an unrecoverable deep stall comes to mind. 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.
- basicplus2 8y ago
  putting and engine on the wing in an undesirable position because of the height of the landing gear is stupid.. 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.

crimsonalucard 8y ago

They should have a philosophy of building aerodynamically stable aircraft rather than relying on software and sensors to produce an illusion of stability.

WalterBright 8y ago
Consider that before WW2, pilots had direct connection between the control and moving the surface. After WW2, planes got too big and heavy for that, and hydraulic boost was added. Starting with the 747, where it is not credible a pilot could control it with muscle, the switch was made to fully powered surfaces. 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.
- crimsonalucard 8y ago
  Right, this makes sense. The system you describe magnifies or reduces the signals going back and forth between the pilot and the control surfaces. It can be modelled linearly and done with an analog system. 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.
  - WalterBright 8y ago
    MCAS was there to prevent a stall, not hide it. All airplanes will stall under varying circumstances. Much of pilot training goes towards avoiding and recovering from stalls, but they still result in crashes.

upofadown 8y ago

The calls for more and better training make me wonder why we don't just train for the relatively rare over pitch characteristic that the MCAS system is intended to prevent. If we can't actually train for that then why are we suggesting that the solution is just being quick to turn the system off? What level of unreliability is required to make it better to just never turn it on?

js2 8y ago

I would be interested in an organizational investigation of Boeing, the FAA and the airlines similar to the investigation of NASA after the Challenger disaster. 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.

pducks32 8y ago
I’m no airplane expert but I find the trend lines of the industry interesting and one trend has been how fuel prices and long lead times on fuel efficiency has lead to formerly continental planes now flying intercontinental. AirBus has really done this well and airlines love to be able to reuse resources. With the MAX there is a sense that airline execs are spooked by a new plane since it requires a ton of new training and maintenance outfitting. So Boeing, possibly smartly, tried to create what these airlines would pay for (a fuel efficient airplane) that would marketable be super similar to a very popular plane. But this lead to rushing the process and making too many affordances and hiding the differences from airlines and training material for fear of spooking business execs worried about cost.

Invictus0 8y ago

Does anyone know why Tunisia refused to work with the FAA?

woodandsteel 8y ago

"First introduced in West Germany as a short-hop commuter jet in the early Cold War" The Cold War started in the second half of the 1940's, so I rather doubt that is true.

cmurf 8y ago

Any design will have consequences, and is thus relevant. But changing it has as much of a consequence as not changing it. Example: Airbus design has "stick" type yokes that are not linked together, and are out of the field of view. If one pilot is using improper inputs, the other pilot won't know. Boeing planes have mechanically connected yokes, both pilots are aware of flight control inputs. Is one a better design than the other? I suggest it's the wrong question, the right question is, what are the consequences of the design on cockpit communication, management, and training and can we meet the ensuing requirements?