Reading the actual NTSB report [1], my first reaction is just my usual awe at the professionalism of the NTSB. They started with a 3000-ft-long debris field and in the end could say "here are the microscopic stress fractures in the left pylon aft mount bulkhead's wing clevis spherical bearing assembly's ball element's forward bearing race".
[1] https://www.ntsb.gov/investigations/Documents/DCA26MA024%20I...
I share your awe of the NTSB and their reports. Here's my favorite quote from the Alaskan Airlines door plug incident[1]:
We determined that the probable cause of this accident was the in-flight separation of the left MED plug due to Boeing’s failure to provide adequate training, guidance, and oversight necessary to ensure that manufacturing personnel could consistently and correctly comply with its parts removal process, which was intended to document and ensure that the securing bolts and hardware that were removed to facilitate rework during the manufacturing process were properly reinstalled.
To be fair, there were a few folks on x avh and the other typical sites who guessed the cause pretty quickly.
Like most things, guessing and proving require vastly different efforts. In aviation, a few more orders of magnitude than most.
The headline is missing an important bit.
Boeing knew of the flaw, and sent a letter to airlines about it. In 2011.
Well yes but Boeing also said it "would not result in a safety of flight condition."
There's a lot of gray going on here.
A former air accident investigator who works as an aviation safety consultant said "It's extraordinary that Boeing concluded that a failure of this part would not have safety consequences," and said the report was "disturbing"
Doesn't seem like gray to me. It seems a company who has a history of cutting corners and ignoring or downplaying safety problems did exactly that in this case too which resulted in the deaths of many people. UPS made an error here as well in trusting Boeing when they said it wasn't a safety issue and they should have installed the revised bearing assembly out of an abundance of caution, but I don't know much they would have known back in 2011 about the changes at Boeing that prioritized profit over safety following the merger with McDonnell Douglas
I think every company operating Boeing aircraft should have reviewed their stance on Boeing directives in light of MCAS and the aftermath by now. If they did not that is a failure of sorts as well.
> I think every company operating Boeing aircraft should have reviewed their stance on Boeing directives in light of MCAS and the aftermath by now. If they did not that is a failure of sorts as well.
Actual question: would an airline have the engineering competence to second-guess an airplane manufacturer's engineering guidance? They operate airplanes but don't build them, and I'd assume they'd out of necessity need to trust the manufacturer's judgement.
They certainly have a responsibility towards their passengers that goes beyond their relationship with Boeing. Passengers trust airlines with their lives, with Boeing they have 'just' a business relationship.
Airlines have every reason to be skeptical of their supplier even if they do not have the engineering competence to second guess them. They could for instance look through their past communications with the manufacturer and see for themselves which advisories they agree with because for instance they are obviously not safety critical, this would then allow them hire specialists to evaluate the remainder for a second opinion.
Agreed. Among multiple organizations that large and complex, the buck can be passed infinitely. There's the lowly worker who installed the flawed part - the safest target, of course - who can pass it to the worker who made it, who can pass it to engineer, to their manager, back to the engineer who the manager relied on after all, the CAD software developer, to the materials supplier, to the machine tool manufacturer, the HVAC contractor who made the manufacturing facility too humid ...
For almost any act, we rely on other people. That doesn't absolve us of our personal responsibility.
There were no passengers on the accident aircraft.
That was in a general case, but in this specific case to satisfy you we can postulate that those on the ground would like to be able to get through their day without having their trajectories intersect with disintegrating aircraft or parts thereof.
If my elevator manufacturer sent me a note about my elevator wire, but says I have to not do anything, because it is probably nothing my number 1 question would be:
Why did you need to tell me about the wire then?
The answer is an attempt to transfer the liability to me. The liability for a thing they think could happen, but didn't tell me about.
That's a very astute observation, I had not clued in to this and I'll be looking for that pattern from now on. Thank you.
It is, unfortunately, a thing. And, far more common than most realize. Responsibility hot potatoe sucks.
perhaps it would behoove a company that routinely has the safety of millions of people a year in their hands to consult 3rd party experts to ensure that those people aren't maimed or killed.
But I'm just some guy with no incentive to endanger human life if I think it will save money so what do I know
They can hire people (or companies) who can give them that guidance, yes.
Maybe the airline doesn’t but their insurance company should, if not directly than indirectly.
That's not how it works. Insurers don't have the resources or technical competence to second guess aircraft manufacturer maintenance guidelines.
When it’s your hundreds of millions of dollars on the line, you go find experts who have the competence needed to do a proper risk analysis.
I would say no. UPS bought the planes from Boeing. Boeing built them, Boeing identified the flaw, Boeing notified it's customers, and said it wasn't an issue.
Frankly I put it squarely on Boeing.
> UPS bought the planes from Boeing
No, UPS bought the plane from Thai Airways International.
> Boeing built them
No, McDonnell Douglas built the plane in question; Boeing hadn't merged with MD at the time this aircraft was manufactured.
The other elements are probably true, but this was not a Boeing aircraft.
I think in light of MCAS every company operating Boeing aircraft should have reviewed their stance on operating Boeing aircraft.
And the worst thing is I don't think even after mcas things have substantially improved there. I've seen more spin and damage control than actual safety focus. They could have launched a huge company program and management reorganization to really turn this mindset around.
I think the biggest issue that Boeing is too big to fail. They'll never fall because the government needs them for all their warplanes.
And what’s more, the FAA is currently moving away from DERs and to ODAs, which is the program that enables Boeing’s flavor of self- oversight
Laws that limit liability promote “cost of doing business“ mentality as if lives are acceptable losses.
This is how you get mentally and morally weak bean counters running companies instead of engineers with a conscience. It’s an engineering company and yet it’s run like a bank that just so happens to have an engineering branch.
Lives have ALWAYS been acceptable losses vs money, it’s just a matter of how much money.
$5mln? $100mln? Old school, $50?
This is exactly why laws need to exist to ensure that human lives are prioritized by companies to a reasonable extent. Companies can often make a lot of money if they can get away with doing things that kill their customers, and we've repeatedly seen them do exactly that. In order to protect the public, corporate greed needs to be constrained by laws and legal consequences just like they're used to help to constrain the greed of muggers and thieves.
In the US we've done a pretty poor job of doing that and it's resulted in countless lives lost and every living person and animal on earth being poisoned. It's long past time our government and its legal system took their responsibility to public safety more seriously.
> out of an abundance of caution
I’m sorry, but this phrase has worn out its welcome.
How? I'm not particularly attached to it, but it seems to continue to be a commonly used expression and this is the first time I've seen someone raise an objection to its use.
Because the phrase and mindset leads to the wrong lessons and actions.
In aviation, there is little room for error. It’s also the case that resources and time are limited. So there are multiple constraints.
We both agree that Boeing is the big problem. I’d also say its a problem of the FAA and the aviation industry.
But UPS? Why would they be taking action “out of an abundance of caution”?
The worst you can say for UPS is they could have sought a second opinion out of “an abundance of caution”, and recommendations of next actions and how.
Keep in mind UPS core competency isn’t aerospace and aeronautical engineering.
Would they even be able to assess the risk of changing said bearings en masse?
The actual lesson here is that most of the advisories and self-certifying from Boeing over the past 30 years need to be reconsidered; most likely redone, by independent third parties and also an FAA with a mandate to be fully independent.
Care to say why?
Seems like a perfectly fine phrase to me.
I am wondering what the exact fail mode here is.
Because my naive conclusion after looking at the part in question is exactly the same "would not result in a safety of flight condition." if the bearing cracked at the point in question it is going nowhere, the bearing is still captive in its housing. hell it looks like it could have been designed as two pieces and it would work the same. the large bolt is what is holding the engine on.
The best I can come up with is that a split bearing causes increased wear on the mounting bracket and nobody noticed for a long time.
Anyhow, here is the ntsb update in question https://www.ntsb.gov/investigations/Documents/DCA26MA024%20I...
That's indeed a very naive conclusion. Once that bearing is gone the stress that it would normally allow to escape on account of rotation would be directly transferred to the metal around it and to the bolts holding the whole thing in place. Guess what broke first?
So if that bearing went that's not quite a smoking gun yet but it would definitely be a step closer to a root cause.
After watching the below video, it's the excess bearing play and thus no-longer-constrained force directions that would seem to be the issue.
With a proper tolerance bearing in place, the force is constrained so that other parts are only stressed in directions they're well suited to handle (because the bearing takes the load).
Once the bearing develops excess tolerance, you've got a bucking engine that (to your point) is directly loading other parts in unexpected ways/directions, eventually causing failure.
The fact that Boeing supposedly modeled this and came up with non-safety critical in the event of bearing breakage... curious how that will turn out.
> The fact that Boeing supposedly modeled this and came up with non-safety critical in the event of bearing breakage... curious how that will turn out.
They'd have to show at least one plane with a bearing gone that still flies as intended. I suggest we break one on purpose, put the full complement of Boeing execs on that plane to prove its safety given the alternative of retracting that statement.
> They'd have to show at least one plane with a bearing gone that still flies as intended.
That depends on the meaning of “safety of flight”. I don’t know what it means in aviation, but do not rule out that there is significant room between “flies as intended” and “result in a safety of flight condition”.
For example, if an engine were to complete drop off the plane, would that necessarily result in a safety of flight condition, or does “the plane will be able to continue take off and land again” mean safety of flight isn’t affected?
Some of it may be related to the 3-engine design, if Boeing had modeled that 2 engines still provided sufficient power in all scenarios.
But a takeoff does seem like the worst time to catastrophically lose 1/3 power, even without FOD intake by the central engine.
My company has a policy limiting the number of high level execs traveling on a plane at a time. I wonder if plane manufacturers have similar restrictions. It’d be an ironic to for them to simultaneously assert that their planes are safe for the general public, and also believe the risk is too high for a planeload of their execs to fly in one.
Controlled flight into terrain is a thing
Niki Lauda, eat your heart out
To see extreme examples of this, look at any wallowed-out/wallered-out through-bore in construction equipment (e.g. excavator buckets), particularly when a pin hasn't been greased, or is seized.
This same scenario combined with the amount of vibration and stresses caused by the engine, should scream "this is a catastrophe waiting to happen" for any engineer.
> Once that bearing is gone the stress that it would normally allow to escape on account of rotation would be directly transferred to the metal around it
The bearing would have to sieze up and the bearing axle be locked to the race. There is some limit to rotational torque even with a siezed bearings.
Metaphor: arthritic joints are not smooth, but they will rotate if given enough torque.
From the images, it looks like the bearing had siezed. So presumably rotational vibration was transmitted to airframe and the vibration caused structural failure?
I'm assuming it is not an issue of extreme rotational torque causing the issue (and given it is a bearing the design is for very little torque there!)
IANAME (not a mech eng)
The forces on that mount are pretty extreme. Once the bearing seized it was really a matter of time before something gave and given the strength of the casing as well as the strength of the material and mount points it was a toss-up between the bolts and the casing. The previous evidence showed a clear order to the bolts breaking suggesting one bolt was heavier loaded than the remaining ones. The new evidence points to a much more extreme failure.
As for your 'limit to rotational torque': seized bearings do not 'rotate if given enough torque' they will break right out of their casings and whatever those casings are surrounded by. The reason is that unlike your cartilage the bearings are orders of magnitude harder than the materials around them. For a bearing to seize indicates that the material has already deformed, you either catch it before the race goes or it will crack and after that all bets are quite literally off. I'm not aware of any design that would spec a bearing in a situation with such forces that would still happily work with that bearing replaced by a bushing welded to the shaft and the surrounding material even if it is statically in exactly the same position.
What you describe is a worn bearing with an excess of play, not a seized one, which tends to exhibit roughly the same characteristics as a welded joint with dissimilar materials.
Bearings are wear items, bearings that are worn or seized are something that should never ever happen in an aircraft, there is no way that this particular design would continue to function with sufficient margin if that bearing would fail. If not caught before it breaks the next flight is going to be a disaster. Take off in a fully loaded aircraft of this size puts extreme stress on the engine mounts. They are designed with all of their parts in working order, this is not a case of 'oh, we'll fix that the next time this craft is in for maintenance'. All parts of a plane that is certified as airworthy are supposed to be operating as originally specified.
The default assumption is that it all looked good during the last inspection and that the time between the failure occurring and the plane going down was short. If it was not that would be highly unexpected. But again, until the final report is in that's speculative, and if anything the people at the NTSB are scary good at getting to root causes.
> What you describe is a worn bearing with an excess of play, not a seized one
Yeah. Worn or seized bearings are relevant to rotation, but on second thoughts, rotation isn't the issue here.
Rereading the PDF, I can see that I entirely misunderstood the function of the bearing and how it failed, and I suspect I've mislead you. The two lugs mislead me! I would guess they make the lug as two parts for redundancy (if the lug was a single part then it's failure would be bad). My previous comment was wildly incorrect about rotation, but now I think rotation is not the issue.
The casing split in half all the way around the circumference at the weakest point (where the recess is), splitting into two pieces, a forward half and a rearward half. The half forward of the split moves forward and the half rearward of the split moves rearward. That is what they inspect for every sixty months to see if the bearing casing has broken.
An unbroken casing is normally prevented from moving forward or backwards by the ball (how the hell do they make the bearing like that?!).
It appears that the unbroken casing itself is designed for the outside to be able to slide forwards and backwards within the lugs (very little movement?).
The primary force this bearing is preventing is pitching of the engine relative to the wing (vertical force). And secondarily to prevent yawing of the engine relative to the wing (horizontal force). Rotation (roll of the engine relative to the wing) has to be prevented by the main mount and the engine surely can't twist much therefore I suspect rotational forces at that bearing are rather irrelevant.
As the engine thrusts and stops thrusting, the thrust changes create pitching forces on the engine, and there would be vertical movement at the broken bearing - a clunk!?
The main mount would flex a little more due to the extra pitch movement; and I guess we'll have to wait and see whether the bearing failure is relevant to the crash. It appears to be a smoking gun, but could be a red herring?
The main mount is obviously not supposed to fail even if that bearing has broken.
Yes, you got it perfectly now.
[flagged]
I owned a machine shop, and I'm the founder of a mid sized CNC gear factory. I think I know my way around bearings, lubrication, press fits and other such bits & pieces.
As for the rest of your comment:
What a load of tripe.
I'm doing the exact opposite of what you claim. I am just taking the bits of evidence already available and rejecting root causes that would require those bits of evidence to not exist, which is entirely valid, this still leaves a massive amount of uncertainty which I have underlined on more than one occasion.
Your suggestion:
> "A bearing that fails for whatever reason, welds it self, and then gets spun around in the bore by its shaft is nowhere near unheard of"
is not compatible with what reputable operators of airliners would expect from their gear and if it happens as a rule people die and the NTSB gets involved, see TFA. This is not just any bearing and this is not your average bench top, industrial or vehicular application, this is an aircraft and a major load bearing component in that aircraft.
> Unless you personally designed the mount of have insider knowledge of comparable ones you are speaking with degrees of certainty that are indicative of ignorance so massive it is functionally malice.
I think that's worth a flag, especially coming from an anonymous potato.
> The BS about how aircraft don't fly with worn bearings is just that, bullshit. Everything has service limits that allow degrees of wear. Now on some parts it might be zero or specific preload, but all that stuff is well defined.
Yes, there is 'acceptable wear over the lifespan of a part' and then there is 'worn out'. Bearings in aircraft are replaced well before they are 'worn out'. Don't conflate design life wear with excessive wear to the point that a part can no longer function.
>I owned a machine shop, and I'm the founder of a mid sized CNC gear factory. I think I know my way around bearings, lubrication, press fits and other such bits & pieces.
Then you have no excuse for having such a nuance free opinion for you must know things are often not obvious at "first glance of pictures someone else took" which is what we're all doing here.
>I'm doing the exact opposite of what you claim. I am just taking the bits of evidence already available and rejecting root causes that would require those bits of evidence to not exist, which is entirely valid, this still leaves a massive amount of uncertainty which I have underlined on more than one occasion.
I disagree. You are acting like this is a cut and dry situation wherein the Boeing advice that this was not safety critical is just wrong on it's face. That assessment was made 15yr ago (perhaps by "old good boeing" engineers) and on a part already under a lot of scrutiny from the other MD11 that lost an engine. Sure they could be wrong, but I wouldn't bet on it so confidently.
This bearing moves a few degrees. It's not like the engine is doing loops around the pylon. It's possible that for whatever reason the bearing stopped doing bearing things as well as it should. Now, this is a plane, everything is light, aluminum and made to flex to varying degrees. It's hard to say where exactly the movement was taking place in lieu of the bearing. Without specific knowledge it's hard to say how the failure happened. Maybe things got loose and failed from stress concentration. Maybe the movement happened in the wing assembly and the force+vibration of making that happen caused the engine mount to fail. You don't know. I don't know. Nobody in these comments know with a sufficiently low chance of being wrong to point the finger in any one direction.
To act like "well of course when the bearing wore/failed/whatever it ripped its mount right in two because now the force was concentrated and the part it was concentrated on was sus to begin with" is to confidently oversimplify the situation.
Engine pylons, landing gear, control surfaces, these are key systems, not the "built to within an inch of their life because they gotta be light" like a lot of other things on an airliner (though I admit the MD11 is a particularly questionable application of this heuristic)
Big planes generally don't fall out of the sky because one party misleadingly labeled something in the service literature. I would be very surprised if there weren't also maintenance failing of some sort here.
> I disagree. You are acting like this is a cut and dry situation wherein the Boeing advice that this was not safety critical is just wrong on it's face. That assessment was made 15yr ago (perhaps by "old good boeing" engineers) and on a part already under a lot of scrutiny from the other MD11 that lost an engine. Sure they could be wrong, but I wouldn't bet on it so confidently.
Well, those good old Boeing engineers and their management have misled the world more than once and no longer deserve the benefit of the doubt. That advisory is black-and-white, there is no arguing with what it says or does not say, you can read it for yourself. If your conclusion is the same as Boeing's then that's fine, you can have a different opinion. My conclusion is that if a load bearing component has these kind of potential issues that you need to act with an abundance of caution because of the price in case you get it wrong.
Yes, that bearing only moves a few degrees. But this is not about how much it moves, this is about what happens when it can not move and given the forces involved the outcome of that is fairly predictable, in spite of your previous statements. There is absolutely no way in which if that bearing is seized or otherwise constrained that this is safe.
> I would be very surprised if there weren't also maintenance failing of some sort here.
I explicitly left the door open for that. But regardless, this bearing should have never failed.
There are a couple of HN members whose pension depends on Boeing stock so I can see how this might ruffle some feathers but this is not a company that has behaved in a morally responsible way when it came to issues such as these om the past and you are effectively already blaming the maintenance people with your 'I would be very surprised if there weren't also maintenance failing of some sort here.'.
That is jumping to conclusions.
I would not be surprised if it were the case, but I also would not be surprised if it wasn't the case. That's the degree to which Boeing has squandered its erstwhile stellar reputation.
But, since you feel comfortable attacking my reputation from behind your shield of anonymity I suggest you flesh out your profile and Bio and tell us a bit about yourself and why you feel so emotionally involved in this.
I apologize... My original comment was poorly thought out and naive, which misled potato and you.
You and potato followed that wrong path and unfortunately didn't correct me or yourselves. I tried to correct myself later (see my sibling comment), but I wouldn't be surprised if I've made another huge cockup with the facts.
> Yes, that bearing only moves a few degrees
It certainly does not move a few degrees (except maybe after a crash).
Thinking back to my one undergrad mechanics paper, I think the design purpose was to make torsions equal zero, so that the mechanical analysis would be tractable.
The torsions should still be extremely low because nothing can rotate (except maybe a tiny amount due to deformations).
If we can't get the engineering facts straight, then our opinions on engineering management are likely to be even more pointless and flawed.
You seem to have gone off the rails as much as potato.
The report seems to be implying that the broken bearing is the cause of the accident. The bearing was still in place after the accident so presumably the bolt didn't shear. If the engine has full acceleration then the engine is pitching upwards against the wing and the force on that bearing is upwards?
I think the report implied the fire occurred at the same time as the structural failure.
What might be the chain of events from a broken bearing to a fire?
[flagged]
[flagged]
Juan Browne (blancolirio) breaks this down:
Deep link to the most relevant portion: https://www.youtube.com/watch?v=q5OQzpilyag&t=5m36s (spherical bearing cut-away diagram, actual bearing again, and failure mode explained)
The FAA has not determined that this flaw did lead to a safety of flight condition. Investigation is still ongoing.
Which may have been a very reasonable conclusion based on what they knew of the issue. The letter sent out reported a split of the bearing race. A split bearing race won't prevent it from supporting the load. It's easily possible that Boeing's simulation of an aircraft operating with a split bearing race was fine.
The NTSB investigation found that for this crash, not only did the bearing race crack, but also that the bearing lugs, which hold the bearing in place, were fractured. I don't have access to the original text of the letter Boeing sent out, but based on the NTSB report, it sounds like only the issue with the bearing race was previously identified. The two may very well be related, but that doesn't mean that the lug fractures are an expected result of the race failure - perhaps some contributing factor made the lugs more susceptible than predicted. It also remains possible that the bearing damage is a red herring; the aircraft was nearing the end of its service life and had known structural issues in other parts of the pylon. The fact is that for more than a decade after the bearing race issue was reported, it didn't result in a safety of flight condition.
The insinuation that Boeing was deliberately trying to hide or downplay a known issue is simply unwarranted. It would be irresponsible for the NSTB not to mention a known issue that could have potentially been relevant, it's not evidence the issue was improperly handled.
What's gray? To me it looks like written proof of incompetence.
Yeah saved boeing losing face and sales by requiring all the planes be grounded and fixed. Just eye it up every 5 years, if you want to.
And that’s how McDonnell Douglas took over Boeing from the inside and eroded its engineering mindset altogether.
Apparently they expected it to blow up on the ground, so technically the plane wasn't flying yet ...
FWIW, the MD-11 was designed by McDonnell Douglas, and manufactured by McDonnell Douglas in 1991, before the Boeing merger. A McDonnell Douglas DC-10 failed in a similar way in Chicago in 1979, so it the issue may go way back.
AA Flight 191 in 1979, 273 dead. American Airlines invented their own engine removal procedure using a forklift and damaged a pylon and mounting bracket. The engine ripped off the wing on takeoff.
Interestingly, the reason American Airlines was removing the engines (and pylons) in the first place was to replace that same aft bearing. McDonnell-Douglas had found that the aft bearing could wear out sooner than expected and issued a service bulletin requiring replacement. There is mention of it in the AA191 NTSB report[1] and also at Admiral Cloudberg's article on the accident[2].
[1] https://www.ntsb.gov/investigations/AccidentReports/Reports/... [2] https://admiralcloudberg.medium.com/rain-of-fire-falling-the...
I'm reasonably certain it was McDonnel Douglas that acquired Boeing with Boeing's own money. Most likely everyone who designed that plane has retired at this point anyways.
It's commonly trotted out, but the people who spearheaded the disastrous changes including mass outsourcing were Boeing for life - with McD people writing alarming memos about outsourcing goals set for Dreamliner
This would be a better defense if not for the aphorism that "McDonnell-Douglas bought Boeing with Boeing's money"
That is the critical bit. They knew about it, and we can speculate that their assessment was wrong, but there is no coverup, no scandal. Sometimes engineers are wrong.
Some are forgetting how risk in technology works: No technology is designed or operated without flaws; that's an absurd approach and impossible to implement.
To reduce negative outcomes, we use risk management: assessing the likely lifetime cost of the flaw, and taking cost-effective measures to reduce the risk to an acceptable level. As a familiar example, redundant mass storage drives are much more cost-effective than high-reliability mass storage drives.
They do mention that the DC10 (this plane's predecessor) was decommissioned for similar issues.
This article does not?
And the DC-10 was not decommissioned. It is, in fact, still in service.
They may have meant grounded, not decommissioned. DC-10s were grounded alongside the MD-11s.
https://www.flightglobal.com/safety/us-faa-broadens-md-11-gr...
Close. I meant decommissioned from the UPS fleet, nearly 25 years ago. MD11 was considered a more modern and flexible replacement.
The DC-10 and MD-11 are both McDonnell Douglas. They merged into Boeing, but instead of Boeing’s safety and innovation oriented culture, McDonnell‘s finance bros won with their cost and corner cutting measures.
Aviation rules are written by blood, you either follow them or you add a few more lines with your own blood.
> Aviation rules are written by blood, you either follow them or you add a few more lines with your own blood.
Please, what fool subjects their own blood to the absence of regulation? If you've got blood on your hands, much better for it to be a customer that has already paid you.
Sure, but the problem is, Boeing is a company that has a proven record of lying about the flaws of their products. There's a huge difference between "shit, nobody thought this part would crack in this way" and "we knew someone would eventually die, but we realized that paying the damages in case this happens is cheaper than preventing the disaster in the first place".
> "we knew someone would eventually die, but we realized that paying the damages in case this happens is cheaper than preventing the disaster in the first place".
The fundamental reality is, we can always spend more to prevent another death; and we must draw the line somewhere.
People don't like it, but your latter example is the risk management I'm talking about, and it's unavoidable. Nobody can make airplanes that have no risk of killing people - the only answer would be no airplanes at all (which would result in more automobile deaths, more deaths because life-saving resources are unavailable, etc.). The calculation of cost per death prevented is a real one, and is done by manufacturers of planes, cars, etc.
The problem with your wording is the criteria of paying damages, rather than the industry-standard value for human life. Again, that is awful to think about but there's no way around it.
Edit: And I'm not saying, at all, that Boeing made the right decision here. I don't know enough to say, and Boeing's safety reputation is poor.
There is some nuance to risk management here. Yes, no one can make something that has genuinely zero risk, but we can and must eliminate particular known risks. A fix being too expensive is not a valid excuse. There are plenty of things we don't do because there is no economical way to do them safely.
Boeing sacrifices 346 people in order to avoid plane recertification. Just so that we don't forget the context of the specific risk management strategies we're talking about.
Yeah but how valuable were those 346 people anyway? Are those lives really worth the tiny decrease in share price?
Please point to someone ITT who is forgetting that. I can't see any such posts.
And "shit happens; suck it up, buttercup" is not an approved PHA determination.
I recall a lot of fingerpointing minutes after the crash by people blaming the presumably foreign maintenance crew.
Even now there is a lot of uncertainty around this crash, maintenance - or lack thereof - or even wrong maintenance could still be a factor. But given the location of the part asking for a 'visual inspection' is a pretty strange move, the part is all but inaccessible when it is in its normal position and even with an endoscope it would be pretty hard to determine whether or not the part had weakened. That's just not going to show up visually until it is way too late unless the part has been especially prepared to announce the presence of hairline cracks.
You'd have to disassemble a good chunk of the wing to gain access to the part based on the pictures I've seen of how it all holds together when assembled.
> blaming the presumably foreign maintenance crew
The same happened with MCAS, the pro-Boeing argument was that if those were American pilots it would have been fine.
As a matter of fact, the same issue did occur to US-based-airlines, and the pilots did catch it. That does not however answer the question of whether they just got lucky, or were more skilled, though there are some indications that it may have been skill.
> As a matter of fact, the same issue did occur to US-based-airlines, and the pilots did catch it.
There was an optional 'AOA disagree' system that an airline could buy that could help pilots know when the MCAS was going crazy. US airlines, perhaps having more money, may have bought those (helping pilots with situational awareness), but airlines in developing countries (with presumably less money) may not have gotten them.
See perhaps §6.4 about Boeing giving that functionality to everyone:
* https://www.faa.gov/sites/faa.gov/files/2022-08/737_RTS_Summ...
Can you share a link?
I’m pretty sure no American airline had the same situation that the airlines with the crash had because they paid extra for the redundant AOA sensor.
The MCAS issue was a major issue, but the ultimate fundamental flaw was Boeing not including a redundant sensor (which is the one that was malfunctioning in the crashes) in the base package as they should have.
The inexplicably considered redundancy in this part an optional extra, and as far as I’m aware there were no US airlines that hadn’t taken the optional extra package.
> they paid extra for the redundant AOA sensor.
There was no redundancy AOA sensor option for MCAS.
All the planes were built with two AOA sensors, with the original MCAS implementation only using data from 1 sensor.
Correct. And you could pay for the MCAS to use both sensors which all US airlines did.
Edit: I was misremembering. Both sensors were enabled on all planes and MCAS only used one at a time on all planes.
What was disabled, unless paid for, was software which displayed to the pilots that the 2 sensors were disagreeing, which would immediately have alerted them to what may have been wrong.
> According to Bjorn Fehrm, Aeronautical and Economic Analyst at Leeham News and Analysis, "A major contributor to the ultimate loss of JT610 is the missing AoA DISAGREE display on the pilots' displays."[109] > The software depended on the presence of the visual indicator software, a paid option that was not selected by most airlines.[110] For example, Air Canada, American Airlines and Westjet had purchased the disagree alert, while Air Canada and American Airlines also purchased, in addition, the AoA value indicator, and Lion Air had neither.[111][112] Boeing had determined that the defect was not critical to aircraft safety or operation, and an internal safety review board (SRB) corroborated Boeing's prior assessment and its initial plan to update the aircraft in 2020. Boeing did not disclose the defect to the FAA until November 2018, in the wake of the Lion Air crash.[113][114][115][116] Consequently, Southwest had informed pilots that its entire fleet of MAX 8 aircraft will receive the optional upgrades.[117][118] In March 2019, after the second accident of Ethiopian Airlines Flight 302, a Boeing representative told Inc. magazine, "Customers have been informed that AoA Disagree alert will become a standard feature on the 737 MAX. It can be retrofitted on previously delivered airplanes."[119]
https://en.wikipedia.org/wiki/Maneuvering_Characteristics_Au...
It’s kinda darkly refreshing that purchases in the tens/hundreds of millions of dollars still try to nickel and dime you.
I believe it goes like this:
Boeing: Do you want a two line code which triggers a potentially life-saving warning when your flying sausage with wings has an important sensor malfunction?
Customer: Of course!
Boeing: That'll be $25K, thanks.
Such a terrible business decision considering the crashes and their impact on Boeing's reputation. If you think a feature will keep the product from catastrophic failure, it should be standard on every unit you sell.
It's what happens when you load a company up with MBA grads who only know cookie cutter business plans with no actual business acumen or experience.
Wait so this is like the bmw heated seat thing? Where all cars have the heaters but they are only enabled via software if you pay? But in an airplane?
Is that what I'm reading?
This kind of thing is not new. In 1998 I worked for a large corporation (I think they were an F100 at the time) that built machines with a feature that could only be enabled if the customer paid an extra fee and had a field technician come out to "install" it.
Unknown to the customer was that all machines were identical. The technician's "installation procedure" was to enter the Service Mode password, select the feature enable option, and exit Service Mode then run a test to make sure it worked.
This is pretty common in commercial/industrial manufacturing. The exception cost to omit certain hardware subsystems when building a product is often higher than the cost of the hardware itself, so it makes more sense to build everything identically and enable/disable features in software.
More or less yes.
If you want to see the way this looks on the flight displays that a pilot sees, this video shows some examples (generated from a flight simulator): https://youtu.be/L5KQ0g_-qJs?si=AtYkellEROnHZ89e&t=349
Yes, and we're not talking about heated seats but about seatbelts, airbags or crumple zones.
I'm sure that a flaw in the plane can be handled more gracefully by the more skilled set of pilots however that's not the point really. Their point was that the flaw in the plane wasn't a big deal and the loss of life and equipment wasn't Boeing's fault, which wasn't true.
The reason we focus on the OEM more than the pilots is that Boeing getting its act together (or being regulated to do so) is more scalable than every pilot in the world becoming more skilled. Individually blaming pilots isn't effective, regardless of whether you're morally for or against it.
[flagged]
Pilots who don't know about systems that are not documented in the manual are dummies?
Given the number of studies on pilot workload and the many harsh lessons learned about how to put together a manual and a training program that has intended outcomes mrktsn is ignoring the realities of operating a vehicle where a second of delay can make a huge difference.
The most stark example was the ambiguity around 'take-off power' and 'take off power', and that is when the writers of the documentation and their management are not trying to pretend a new aircraft is the same as a complete redesign of an older one with which besides the name and the operational niche it has relatively little in common.
I always wondered why there were no whistleblowers before this led to accidents. Or were there?
Ah, whistleblowers. Always and forever committing suicide. Turns out thinking you can stab the gorgon with no consequences is a form of mental illness.
[flagged]
> That does not however answer the question of whether they just got lucky, or were more skilled, though there are some indications that it may have been skill.
What a load of bullcrap. Full stop.
The crews of the two crashed 737Max were also well trained, skilled professionals.
That the US-based crews decided to re-engage the auto-pilot, and with that action, by sheer luck, managed to bypass the fatal MCAS issues, shows you exactly what it was: sheer luck.
These pilots reacted to a system malfunction of a system they hardly knew existed (thanks to Boeing's lies), that changed the aircraft subsystems behaviour in fundamental, undocumented ways compared to the previous generation of 737s, and that they were therefore not trained to handle. So skill differences did not enter the equation, luck did.
The choice was between doing the manual procedures they were trained to do to try to regain control, and the hail mary approach of re-engaging the autopilot wtith the hope the problem went away. With no time to do both. The crashed crews chose option 1, the US crews option 2.
Shear luck is mostly used when you hope the sheep you're shearing doesn't kick you in the face.
Takes me back to a two decade long robotic sheep shearing project Shear Magic ..
there's a 1992 wrap up book on that: https://www.cambridge.org/core/journals/robotica/article/abs...
all a bit before Boston Dynamics.
Lol! Corrected. :-)
I am with you, this is just BS. The whole point of 737Max what that experience with 737 was enough, with maybe some small adjustments. Now claiming that you need to be some kind of super-pilot to keep the 737Max in the air when the thing tries to kill you is total bullshit.
This is like Tesla claiming that all crashes due to autopilot failures are driver faults because they are not properly trained... it is supposed to be a car driveable with a regular car license! If you need extra train to drive it properly, be explicit.
[flagged]
Did you verify the 35 sources it used or are we now supposed to just trust everything on the internet if an LLM prints it now?
No, that's why I put a disclaimer. Can you show me you work demonstrating that US pilots are superior? I will replace the grok link with your work if you like.
Until then, the AI generated one is much better sourced than the "US pilots are superior and would have handled MCAS" claim.
Please stop spreading cancer.
[flagged]
Or you can simply delete the message. You've posted a race-loaded analysis from an AI that called itself MechHitler because "somebody" decided to mess with the prompt.
[flagged]
> I guess you should do your own manual research showing that the US pilots are indeed superior and post it now.
Someone who can’t cook can still identify a shit sandwich as bad food.
I don't see any identification attempt, its just a freak out over the sandwich shop they apparently hate with passion.
Most likely just luck. These days US pilots can’t keep their planes separate from their helicopters so we're not exactly sending our best up there.
Mmmm…. Not saying us pilots are universally great, but I have definitely seen a significant regression from the mean in many foreign cohorts. I imagine it’s due to fundamental differences in the concept of training. It’s one of the things besides war that fear based societies seem to do better than shame based societies.
There exists a concept called "regression to the mean". I don't think "regression from the mean" means anything.
There is no way pilots form all over the world could "regress to the mean". They could not have been all, or most, "above the mean". The mean would be higher then.
Well, it may not be a term of art, but regression from the mean is reasonable to imagine as a failure to rise to the mean level.
Civilian pilots have to consider that they are flying in heavily congested airspace with 200 passengers in the back. They are not LARPING Chuck Yaeger in the right stuff.
Well, not with that attitude, they aren't. But I've been on some charters where I'm pretty sure that they were, in fact, larping Chuck Yeager. I've seen a solid 2.5-2.8G turns in a 737, as well as some cornea-peeling rotations to max climb. It's kinda funny how things sometimes change when the plane isn't full of paying passengers.
I mean, those are pretty standard maneuvers, up to 4gs or so, in small aircraft, and I used to fly aerobatic frequently... but it just hits different somehow on an aircraft that weighs 70 tons and flexes visibly.
It’s true that they don’t send their best
Between US pilots having to lie about their mental health and then having average pay far lower than people who use Claude code daily, they really aren’t sending their best.
Unironically whatever you think pilot training involves, we should probably double it. This would be extra good as raising the prices of flights will make fewer people fly. Far too many people right at this moment who shouldn’t be flying are flying.
If we could finish by forcing all airline seats to be at business class quality (thus average flight ticket costs are about 2X now as economics of scale kick in), than flying would become a humane practice rather than war crimes in the sky.
It's not really the same. Pilots need extensive training for how to handle emergency situations and maintenance crew don't. It's not super harsh to say that pilots in different regions are at different levels for those weird situations. It is super harsh to say that maintenance crews in some regions can't do their baseline job.
That's entirely false, the maintenance crew are highly trained people they don't figure out things on the go and when they have to figure out solution to an issue, it's based on what they know about the aircrafts from their training.
Maintenance crew are highly trained people that in strange situations can pause their work to figure out a fix and ask experts what to do.
Very different from how a pilot has to handle strange situations. Being ready for anything in an airborne plane without a pause button is so much harder, impossibly hard, and not every air authority tries as hard to reach the impossible.
Stand outside an engine test cell for a while and tell me that maintenance crews don't deal with emergencies. I'll bet they do so more often than pilots, we just don't hear about it because there are no passengers at risk. Nobody is going to make a 'Sully' like movie about the maintenance mechanic that spotted an issue with a part under test before it led to one or more catastrophic failures. They're more likely to make a lawyer the lead than the mechanic.
This is not just filling out reports and looking at stuff, they're in no way comparable to your local garage mechanic (and not to dump on them either: they too have to deal with out of the ordinary situations).
The responsibility issues are the same as with the pilots as well, they fuck up people die.
I didn't say there aren't any emergencies, but the emergencies are not on the same level. And I said they're highly trained, you don't need to convince me of that. Nor do you need to convince me they're important. Those are entirely separate issues.
Also what fraction of engine test cell use is for engine maintenance? Is it a big amount?
But if that kind of test goes wrong the main outcomes are "hit stop" and "oh no it's too late". An emergency like that is not where much of their expertise is needed, their expertise is in other parts of their job.
> Also what fraction of engine test cell use is for engine maintenance? Is it a big amount?
After every overhaul. Typically every 2500 to 15000 hours depending on the type of engine and the workload. It depends on many economic factors whether or not an overhaul is economical, in some cases it is cheaper just to buy a new engine.
Totally agree. Maintenance staff often get ignored. It is worth pointing out how skilled these people are and, in general, how dedicated they are to their task. It is also worth pointing out that often maintenance do get involved in emergencies, especially those that work on the line. I had a guy catch a bleed air leak and signal fire in seconds, saving the engine and potentially a lot more. We like to think of the pilots, but maintainers deserve a lot of credit.
Boeing themselves, including their CEOs, kept repeating that bullshit. Even after the FAA finally realised the issue, and refused Boeing's first attempted fix that relied on pilots being able to identify the situation and enact the procedure within 10 seconds (in various tests in a Southwest training center, it was around 30s on average). Then the FAA mandated a full redesign of the MCAS system to actually rely on two sensors and handle disagreements. And Calhoun kept repeating that "this wouldn't have happened with American pilots".
[flagged]
My favorite is when the pedestrian in the shoulder was difficult to see.
Charlie Kirk thought black people shouldn’t be allowed to be pilots. This is a man we are supposed to celebrate according to MAGA…
Thank you this document is so much more straightforward than most YouTube videos covering the same.
One thing that worries me about the current political climate is that everything can be politicized. Do we know that behind the scenes Boeing wasn't paying a bribe for better treatment in the report? Or do we know that this report is especially damning because they refused to bribe? I guess we never knew for sure but the level of corruption now is so high I just have no faith that there hasn't been meddling in these investigations. It's the pernicious effect of corruption in a society and I don't think we're ready for it.
I’m guessing that manufacturers know of lots of flaws in the parts they make.
Hopefully they don't usually downplay the risks of dangerous known flaws in critical parts like Boeing seems to have done in this case.
Is that your professional assessment as an aerospace engineer, or as a software engineer?
It's my assessment of the professional assessments of experts such as aviation safety consultant and former air accident investigator Tim Atkinson and former FAA and NTSB investigator Jeff Guzzetti, as well as the contents of the NTSB's report, and Boeing's well documented history of putting profit over safety.
I believe that it's the opinion of experts that Boeing either misjudged the safety risk of the bearing assembly when they should not have or that they incorrectly downplayed that risk when disclosing the flaw to their customers and I'm inclined to believe those experts because Boeing has already demonstrated themselves to be outright dishonest and negligent when it comes to the safety of their products.
That said, while I would not be surprised if things truly are as they currently appear to be, my assessment is always subject to change if additional information comes to light which makes that less likely to be the case.
They learn pretty quickly to downplay things when their whistleblower collegese either fall down the stairs or kill themselves after telling loved ones that if they die it was not by their own hands.
You can't in good conscience advertise a complex assembly as fit for some purpose without knowing how close the component widgets are to their various modes of failure.
I wonder on what basis Boeing thought that damage to a load-bearing part could be safely ignored? I hope it wasn't "nothing bad has happened for 50+ years, so it's unlikely to happen now"?
>I wonder on what basis Boeing thought that damage to a load-bearing part could be safely ignored?
Usually this is because the design constraints are complex and in satisfying one you wind up having orders of magnitude more overkill than you need on others.
For example, in situations involving hollow shafts with through shafts or perhaps fluid passages often times you wind up with insanely huge for the load bearing supporting the outer most part because it simply needs to be that big in order to fit around the shaft and have space for reasonable sized roller elements for the speed and realistic race thicknesses, etc. Sure you could go custom, but $$, sure you could use needles or balls, but maybe the stuff on either side has reasons it shouldn't be hard like a race and that might add assembly/construction cost. Now say this overkill bearing is held up by a big web in a big honkin cast housing, because the housing needs to be like that for structural reasons (say it's a specialty pump or maybe this housing is load bearing in the overall assembly, like a tractor's gearbox). Now, say this bearing is in some more complex gearbox that has lubrication windage problems. A valid fix might be to go and cut out a chunk of the web that holds this bearing. Sure it's only supported by 300deg now instead of 360, but it was so overkill to begin with that doesn't matter.
Edit: better example: You can roach dozens of automotive cartridge style wheel bearings without hurting the knuckle it presses into because the knuckle has to be so strong to withstand suspension forces you basically can't apply enough force via the wheel failure to break it and the assembly becomes unserviceable faster than you can get to the point of damaging it by wearing through it.
Edit2: You also need to consider the cost of QA and testing. Sometimes it's cheaper to do a simple overkill waste of material design than something than to do speed holes and engineered webs, etc, etc, because all those features add testing cost as well as manufacturing cost and (especially in ye olden days of the slide rule) make it harder to predict stuff like resonance, exact failure mode, etc, etc and every feature has to be QA'd to some extent. And this all needs to be balanced against expected production volume.
"There are two wings right?"
Every five years feels too infrequent. These are planes that are 30 years old and have done 100,000 hours of flying. Apparently UPS policy is to keep them around for about 35 years to maximize the ROI. But maybe once they hit a particular age they need to be inspected deeply every few months.
I am not an expert, however. Can metal fatigue be detected with such infrequent inspection?
Sounds like it is included as part of standardized airplane checks based on age of aircraft + hours flown.
[1]: https://en.wikipedia.org/wiki/Aircraft_maintenance_checks#AB...
On things like D check, the aircraft is essentially completely taken apart and inspected at that level typically taking 50,000 man hours and 6 month-1 year of time.
Thanks for this post. I’m blown away by that 50,000 hours figure.
The article mentions the cost and that Boeing underestimates it. When you divide the cost by the number of hours, it seems very reasonable. Parts and materials being included. I’m surprised any job that extensive isn’t even more expensive.
Alternative to paywall: https://archive.ph/8xF1w
Whenever I see these I think of Fight Club
Isn't it a mostly Boeing project that is going to go around the moon next month? I'm really afraid for that crew.
Why would you be afraid for them when the Orion capsule worked so flawlessly...oh right.
Are you talking about Starliner? Starliner's 2 flights have been problematic to say the least, but Orion's single (uncrewed) flight went pretty well.
And Lockheed and Airbus are the prime contractors on Orion, not Boeing.
Yeah, totally borked that one up. Apologies to the Orion team for erroneously tagging them with Boeing's baggage.
This is the problem with regulatory capture (corruption), "self-regulation", and billionaire bootlicking bozos who shoot their mouths off about "red tape" and "big gubberment".
The part was redesigned without the groove but wasn't mandated because Boeing said even the old part could be used, which is insane. Clearly, the new part wasn't installed and likely 1-2 inspections failed to notice it was broken.
Insane that we can have places like the skunk works create the sr71 and operate on shoe string budgets but the largest passenger plane company in the world can’t accurately assess risk on planes far under the former planes Mach 3 record
Look up the hull loss numbers on the SR-71. More than a third of them were lost in incidents despite never making contact with the enemy.
It was also insanely expensive to operate: $300k/hour in 1990 dollars, and there aren’t reliable numbers on development costs with all of the black budgets.
33 percent attrition and could only fly once a week.
I know satellites and drones have replaced the sr71 but it would be cool if someone would build a plane as capable again.
It was replaced because the USSR managed to shoot one down.
Spy satellites are as of yet off limits.
Anti-satellite weapons have been demonstrated by the US, USSR, Russia, China, India, and if you stretch a bit Israel (they shot down a Houthi missile while it was above the Kármán line, the same system is probably capable of use as true anti-satellite weapon). Nobody has shot down anyone else's spy satellites, but it's not because it's impossible.
I think you might be misremembering the shoot-down of a U2 plane, which was also a U.S. spy plane operating around the same time.
> was
U2 is still in operation.
is there a reference for the USSR shooting an SR-71 down?
There is no reference for this, because it never happened.
the point I was trying to make is that the creation of the sr71 was a physics defying problem and something considered nigh impossible. A passenger plane has much less complex expectations. Now don't take this to meant none at all, of course they have to operate 24/ 7 and have high reliability and safety. However, in a world where we can build the SR71 I don't see what we can't build the latter. We can and should be building better planes. I think that's pretty evident with this issue and the infamous software issue of the other boeing planes.
The MD11 in question is a defunct design from 38 years ago. We are building better planes now.
UPS is as old as the plane in question and has only had three fatal accidents in that time with millions of flight hours, most of them on retired airliner frames.
Yes, Boeing had a monumental fuck up with the MAX redesign. However, their last blank page design was the 787 and is seen as completely revolutionary in terms of materials and efficiency. Let’s talk about that plane. It burns 20% less fuel than the planes it was designed to replace, and has a number of incredibly impressive engineering feats purely for passenger comfort- pressurization altitude and window size being the most impressive. It doesn’t sound impressive, but the design ask is: make a lighter plane, with bigger holes in the structure, that can withstand more pressure, and use a material and process that has never been used before. The only fatal incident on the 787 is still under investigation, but is almost certainly pilot error or suicide. Other plane and engine safety technology have allowed ETOPS making it possible to use efficient twin engine jets operate overwater flights that would have been unthinkable 40 years ago.
Jets today are quieter (by such a huge margin that it isn’t legal to operate the original 707 engines at most western airports), more efficient and safer than ever.
In the era that the SR-71 existed in, it was actually pretty common for planes to crash due to design defects (DC-10, Comet, 707, and more). The 737 MAX defect was so shocking because it has been 50+ years since that was common.
The SR71 is a simpler plane in many ways than a modern airliner. The composite technology to build a 787 didn't even exist at that time, and the engine alone on the 787 is far more impressive engineering and material science than the SR71. And there are two companies that figured out how to make them without a blank check from the CIA. The 787 produces more than double the thrust of the SR-71, and most passengers barely are aware of the miracle they are participating.
The SR-71 is an undeniably cool project. I have seen several up close, sat in the cockpit and they are literally awe inspiring. What we build today are airliners that are seemingly boring but built and designed with technology and materials that Skunkworks couldn’t have even attempted.
We aren’t building things like the SR-71 anymore because we are building things that are far better and more complex. We have Lockheed producing the F-22 and F-35, multiple companies reusing space launch rockets, etc. the real problem is that we have lost our sense of wonder at just how impressive modern aerospace engineering is.
I don't see that as a valid comparison. SR-71s could operate with a much higher level of risk than commercial passenger planes. IIRC, SR-71s leaked fuel on the ground, and their wings dragged on the ground without special attachments. Pilots needed special pressure suits, etc.
I also expect that they were much less complex than an aircraft that provides a comfortable, pressurized cabin; the high level of safety mentioned above; freight capacity; etc.
Also, despite Boeing's recent problems, I would guess that commerical passenger planes are far more safe than they were decades ago when the SR-71 was developed. Accidents were much more common despite many fewer flights, iirc.
12/32 SR71s were lost in the 33 years they were flying. 11/200 MD-11s have been hull-lost from 1988-2025. Not to mention that passenger/cargo planes will put on a lot more flight hours than the SR71s did in a given year.
the SR-71 leaking fuel on the ground was not a design flaw. it was designed to be operated at speed where things would expand to fill in. if they were filled in on the ground, they'd have no place to expand at speed/temps. the risk assessment was that it was better to leak fuel on the ground rather than blowing up at speed/temp
Right, it was risk management. I doubt that leaking fuel would be acceptable risk management for a commercial passenger plane at a public airport.
Obviously they could have designed something that could expand and contract if they thought it was worth it.
They designed special fuel that wouldn’t catch on fire under normal circumstances.
Also, this was done because airframe skin temps exceeded 400F during flight due to the high speeds.
Much less complex? I'm not sure about that for a plane that's expected to travel so fast. In terms of features I'm sure modern passenger planes have quite a bit more. I'm sure planes are absolutely safer now, the point I'm trying to make is the SR71 was thought to be almost impossible to make yet they were able to do it with an impressively small team and (rumored) budget. Yet so many years later we struggle to make reliable workhorse planes that have no such expectations of going faster than anything before. I don't think it's a stretch to say that we could and should be making much better planes.
> have no such expectations of going faster than anything before
They have many other unprecedented expectations, such a fuel usage and safety.
The U-2 is the plane that drags the wings on dolly wheels.
Oops, thanks.
The SR-71 is pressurized. Not to sea level pressure, obviously, but it wasn't exactly unpressurized either. The main reason the crew wore pressure suits is for heat retention and oxygen delivery.
Interesting; I wonder why the bothered to pressurize it. It would seem to add a more complexity to many things - every seal, seam, etc - plus the pressurization system. Maybe some equipment ran better with more pressure.
Even commercial passenger flights are not pressurized to sea level; I think it's something like 8,000 ft. IIRC, Boeing's 787 was designed to be pressurized a bit more which, from on-the-ground experience acclimatizing to altitude, I think could make a noticeable difference.
Running stuff in an unpressurized environment at that altitude brings another set of challenges.