Why the Boeing 737 will never take the place of the 757(thepointsguy.com)
thepointsguy.com
Why the Boeing 737 will never take the place of the 757
https://thepointsguy.com/news/737-never-replace-757/
183 comments
Having worked for 3 years designing 757 flight controls, it's a special plane for me, too. I always enjoy finding the bird I'm booked on is a 757. Some of the guys I worked with on it were an engineer's engineer. I lost my fear of flying through working on the 757.
Would you being willing to elaborate on what makes it special to you? I'd love to know more!
Years ago I worked at Ames on the ACES system (minor but fixes and a Greenfield projects involving data/flight path visualization), but I felt the airplanes themeselves were these magical black boxes. I'd would appreciate having a deeper understanding about how they differentiate from one another in a non-superfical sense.
Years ago I worked at Ames on the ACES system (minor but fixes and a Greenfield projects involving data/flight path visualization), but I felt the airplanes themeselves were these magical black boxes. I'd would appreciate having a deeper understanding about how they differentiate from one another in a non-superfical sense.
Simply, what makes it special is I had a hand in it. Every time you fly on one, you're betting your life on my parts. I know how it works, and I know why it's safe.
I worked specifically on the stabilizer trim system (like the one in the news on the 737MAX), and did some work on the elevator system. In particular on the latter, I did many calculations to prove it would not flutter (dynamic instability).
My very first assignment was to size the stabilizer trim jackscrew. I panicked and told my lead I had no idea how to do that. He laughed and said of course you do, it's a simple column buckling problem. Which of course it was, and I sized it.
A couple years later, and the first jackscrew gearbox assembly came off the line, and was doomed to be subjected to the ultimate load test. Any buckling, cracks, deformation, etc., would be a failure. The test guys told me they were gonna bust my jackscrew.
They hooked it up to this big ugly iron I-beam with a hydraulic ram to compress my green BMS10-11 painted gearbox and shiny chrome steel jackscrew (made by Saginaw Gear, who made the best kick-ass forgings).
They started cranking up the pressure, while I stood around anxiously watching it. Slowly, the I-beam bent into a nice curve. We didn't have to make any changes to any of the stab trim system due to test failures. Whaddya know, the math works! So I am not a bit afraid to fly on a 757. The seating can be cramped, but that's the way it goes these days.
As far as know, there have been no in-service failures of that system. The 757 itself has a fantastic safety record, of which I am proud to have contributed to. The last D conference I flew to on a 757 operated by Iceland Air, yay!
At the time I bought a bunch of Boeing stock as a result of my confidence in Boeing, and it has paid off handsomely.
I worked specifically on the stabilizer trim system (like the one in the news on the 737MAX), and did some work on the elevator system. In particular on the latter, I did many calculations to prove it would not flutter (dynamic instability).
My very first assignment was to size the stabilizer trim jackscrew. I panicked and told my lead I had no idea how to do that. He laughed and said of course you do, it's a simple column buckling problem. Which of course it was, and I sized it.
A couple years later, and the first jackscrew gearbox assembly came off the line, and was doomed to be subjected to the ultimate load test. Any buckling, cracks, deformation, etc., would be a failure. The test guys told me they were gonna bust my jackscrew.
They hooked it up to this big ugly iron I-beam with a hydraulic ram to compress my green BMS10-11 painted gearbox and shiny chrome steel jackscrew (made by Saginaw Gear, who made the best kick-ass forgings).
They started cranking up the pressure, while I stood around anxiously watching it. Slowly, the I-beam bent into a nice curve. We didn't have to make any changes to any of the stab trim system due to test failures. Whaddya know, the math works! So I am not a bit afraid to fly on a 757. The seating can be cramped, but that's the way it goes these days.
As far as know, there have been no in-service failures of that system. The 757 itself has a fantastic safety record, of which I am proud to have contributed to. The last D conference I flew to on a 757 operated by Iceland Air, yay!
At the time I bought a bunch of Boeing stock as a result of my confidence in Boeing, and it has paid off handsomely.
And here is the kind of catastrophe, that was prevented by Walter's calculations:
https://en.wikipedia.org/wiki/Aeroflot_Flight_8641
https://en.wikipedia.org/wiki/Aeroflot_Flight_8641
The 757 jackscrew gearbox is a scaled down version of the 747 one. There was one failure of the 747 jackscrew:
https://en.wikipedia.org/wiki/National_Airlines_Flight_102
A loose armored vehicle crashed into the jackscrew snapping it. There is no possible recovery from that. I cringe every time I see the video of that one. Horrible.
https://en.wikipedia.org/wiki/National_Airlines_Flight_102
A loose armored vehicle crashed into the jackscrew snapping it. There is no possible recovery from that. I cringe every time I see the video of that one. Horrible.
I thought the main cause of the crash was the cargo weight, didn't know it had also damaged the control hydraulics. Wonder if it could have been recovered if they'd had those controls.
Going down the wikipedia rabbit hole, the Aeroflot page refers to https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261
A few days ago I'd asked how the NTSB gets good co-operation from the airlines in these cases (thanks for the answers at the time!)
The interesting point to me was the contrast between the 2 cases.
In the Aeroflot case:
> Three engineers who signed the jackscrew drawings were convicted.
In the Alaska Airlines case:
> The investigation then proceeded to examine why scheduled maintenance had failed to adequately lubricate the jackscrew assembly. In interviews with the Alaska Airlines mechanic at San Francisco International Airport (SFO) who last performed the lubrication it was revealed that the task took about one hour, whereas the aircraft manufacturer estimated the task should take four hours. This and other evidence suggested to the NTSB that "the SFO mechanic who was responsible for lubricating the jackscrew assembly in September 1999 did not adequately perform the task". Laboratory tests indicated that the excessive wear of jackscrew assembly could not have accumulated in just the four-month period between the September 1999 maintenance and the accident flight. Therefore, the NTSB concluded that "more than just the last lubrication was missed or inadequately performed".
I couldn't find any mention of personal sanction.
Just surprised by the difference in treatment between the 2 cases...
A few days ago I'd asked how the NTSB gets good co-operation from the airlines in these cases (thanks for the answers at the time!)
The interesting point to me was the contrast between the 2 cases.
In the Aeroflot case:
> Three engineers who signed the jackscrew drawings were convicted.
In the Alaska Airlines case:
> The investigation then proceeded to examine why scheduled maintenance had failed to adequately lubricate the jackscrew assembly. In interviews with the Alaska Airlines mechanic at San Francisco International Airport (SFO) who last performed the lubrication it was revealed that the task took about one hour, whereas the aircraft manufacturer estimated the task should take four hours. This and other evidence suggested to the NTSB that "the SFO mechanic who was responsible for lubricating the jackscrew assembly in September 1999 did not adequately perform the task". Laboratory tests indicated that the excessive wear of jackscrew assembly could not have accumulated in just the four-month period between the September 1999 maintenance and the accident flight. Therefore, the NTSB concluded that "more than just the last lubrication was missed or inadequately performed".
I couldn't find any mention of personal sanction.
Just surprised by the difference in treatment between the 2 cases...
If you read further, there is an even more interesting bit -
> In 1998, an Alaska Airlines mechanic named John Liotine, who worked in the Alaska Airlines maintenance center in Oakland, California, told the Federal Aviation Administration that supervisors were approving records of maintenance that they were not allowed to approve or that indicated work had been completed when, in fact, it had not. Liotine began working with federal investigators by secretly audio recording his supervisors. On December 22, 1998, federal authorities raided an Alaska Airlines property and seized maintenance records. In August 1999 Alaska Airlines put Liotine on paid leave, and in 2000 Liotine filed a libel suit against the airline. The crash of AS261 became a part of the federal investigation against Alaska Airlines because in 1997, Liotine had recommended that the jackscrew and gimbal nut of the accident aircraft be replaced, but had been overruled by another supervisor.In December 2001 federal prosecutors stated that they were not going to file criminal charges against Alaska Airlines. Around that time Alaska Airlines agreed to settle the libel suit by paying about $500,000; as part of the settlement, Liotine resigned.
The deficiencies of the FAA regulator regime should be obvious from this case, but it seems that no-one was held accountable for Alaska Airline's lack of safety culture in its maintenance operation.
> In 1998, an Alaska Airlines mechanic named John Liotine, who worked in the Alaska Airlines maintenance center in Oakland, California, told the Federal Aviation Administration that supervisors were approving records of maintenance that they were not allowed to approve or that indicated work had been completed when, in fact, it had not. Liotine began working with federal investigators by secretly audio recording his supervisors. On December 22, 1998, federal authorities raided an Alaska Airlines property and seized maintenance records. In August 1999 Alaska Airlines put Liotine on paid leave, and in 2000 Liotine filed a libel suit against the airline. The crash of AS261 became a part of the federal investigation against Alaska Airlines because in 1997, Liotine had recommended that the jackscrew and gimbal nut of the accident aircraft be replaced, but had been overruled by another supervisor.In December 2001 federal prosecutors stated that they were not going to file criminal charges against Alaska Airlines. Around that time Alaska Airlines agreed to settle the libel suit by paying about $500,000; as part of the settlement, Liotine resigned.
The deficiencies of the FAA regulator regime should be obvious from this case, but it seems that no-one was held accountable for Alaska Airline's lack of safety culture in its maintenance operation.
Not to nitpick, but the failure mechanism in the crash and what Walter was testing are slightly different.
Fatigue failures like the one in the crash are from multiple sub-maximal loads (look up "S-N" curves for more info). In other words, fatigue comes from cycling lower loads many times on a part. Buckling calculations look for maximal load failures on a column (i.e. a single larger load event that can make it fail).
The link is a great example of a real world case study (and thank you for finding it!), and no doubt somebody was doing fatigue calculations on the jackscrew at Boeing as well. I just wanted to add a bit of nuance
Fatigue failures like the one in the crash are from multiple sub-maximal loads (look up "S-N" curves for more info). In other words, fatigue comes from cycling lower loads many times on a part. Buckling calculations look for maximal load failures on a column (i.e. a single larger load event that can make it fail).
The link is a great example of a real world case study (and thank you for finding it!), and no doubt somebody was doing fatigue calculations on the jackscrew at Boeing as well. I just wanted to add a bit of nuance
> no doubt somebody was doing fatigue calculations on the jackscrew at Boeing as well.
Yes, they were (the stress group). The airframe was designed for 62,000 hours of operation, then scrapped due to fatigue considerations. Fatigue was a bit of a black art at the time, with rules based on extensive testing and experience. It's much better understood today.
Take a paper clip and bend it back and forth. Eventually, it will break. That's fatigue.
Yes, they were (the stress group). The airframe was designed for 62,000 hours of operation, then scrapped due to fatigue considerations. Fatigue was a bit of a black art at the time, with rules based on extensive testing and experience. It's much better understood today.
Take a paper clip and bend it back and forth. Eventually, it will break. That's fatigue.
> It's much better understood today.
When I studied this it seemed to just be empirical, as in you calibrate some law to some measurements and use that to tell you when it is likely to fail. Has this changed?
When I studied this it seemed to just be empirical, as in you calibrate some law to some measurements and use that to tell you when it is likely to fail. Has this changed?
I simply heard it had gotten much better. I don't know the details, as I pivoted to programming.
>no doubt somebody was doing fatigue calculations
I'm always surprised by the general publics' lack of awareness and understanding of fatigue. And then seeing the figurative lightbulb illuminate after asking them how they would break a metal clotheshanger, without any tools.
Anyway, it may not have been his personal responsibility, but certainly fatigue must have been a significant consideration during design, since (afaik) it's most often the controlling factor in lifetime estimates for structural components in airframes.
I would strongly assume the same would apply to a component who's expected failure mode might be buckling.
I'm always surprised by the general publics' lack of awareness and understanding of fatigue. And then seeing the figurative lightbulb illuminate after asking them how they would break a metal clotheshanger, without any tools.
Anyway, it may not have been his personal responsibility, but certainly fatigue must have been a significant consideration during design, since (afaik) it's most often the controlling factor in lifetime estimates for structural components in airframes.
I would strongly assume the same would apply to a component who's expected failure mode might be buckling.
True, the design is one important part, but the design can be 100% on, but the manufacturing and the operational inspections are important to present failures too. Variance from controlled manufacturing conditions can result in parts that basically look and perform ok at first, but are at risk of failing early, that's why aircraft have inspection schedules - that are sometimes increased due to increased cycles on some routes/airports.
(and of course there is the case of the part being damaged somehow, where some of the other comments have linked cases where this happened catasropically).
(and of course there is the case of the part being damaged somehow, where some of the other comments have linked cases where this happened catasropically).
Hmmm...
I'm not real familiar with that mass production qaqc.
Is there a term that describes a minimum design spec (or similar aspect), that takes into account the actual manufacturing (and other) variances?
I'm thinking that in construction, a rough equivalent would be a designs constructability / bidability review.
I'm not real familiar with that mass production qaqc.
Is there a term that describes a minimum design spec (or similar aspect), that takes into account the actual manufacturing (and other) variances?
I'm thinking that in construction, a rough equivalent would be a designs constructability / bidability review.
The design may call out a specific material and how to manufacture it, say make this part out of 6061 Aluminum, and. mill it in this way. You can look up the standard properties of that material. But depending on how that material is worked, cut, bent etc, you would expect in come cases some changes in the material properties or just sensitivities to fatigue. E.g. if you cut a sharp corner into that metal, fatigue will increase in that corner over the life of the part, so maybe you specify rounded corner - but how much it makes a difference you won't do necessarily a whole specific detailed study on it unless its a critical part or corner. If it's milled, if the machine that day has a duller bit, maybe it heats up the part more, and the material properties shift a bit more due to the heating. All these and are controlled in the process, but are still little things lead to variation, and maybe the controls fail one day and some slightly different aluminum makes in into the process.
For critical parts on the aircraft, there is the backup of inspecting for aspects like accelerated fatigue just for variation of manufacturing, of environmental contributors, etc. It's a lot like security defense in depth - many layers of protection for lives (and aircraft industry trustability linked to profitability too) at stake.
For critical parts on the aircraft, there is the backup of inspecting for aspects like accelerated fatigue just for variation of manufacturing, of environmental contributors, etc. It's a lot like security defense in depth - many layers of protection for lives (and aircraft industry trustability linked to profitability too) at stake.
I'm not sure what you're asking but there is term in manufacturing called DFM or design for manufacturability. Otherwise, design drawings are loaded with specs that call out design tolerances etc. QA and process control are used ensure these tolerances are met
Maybe a dumb question, but wouldn’t you have expected it to break at the target max load? I would have thought it being stronger than required would mean it was heavier than necessary?
That is a fun question. Boeing had two groups - the design group, and the stress group. The design group does the design, the stress group checks it. I was in the former.
One day, I got called into the stress group, where they told me they were unhappy with my parts. I asked why, they said there just barely strong enough for the ultimate load, only about 1% over. They said they'd feel more comfortable with 10% extra strength.
I said this was no coincidence, I used math to size the part to the load, rather than guessing at a size and checking to see if it was strong enough. The requirement was the ultimate load, which is 150% of the maximum load that could ever be expected.
I asserted that I designed to the design requirement, and an extra 10% would make it overweight. Brat that I was, I said if you guys were unhappy with the design requirement, increase it. They grudgingly signed off on it.
The reason it didn't break on the test stand is because all parts vary in size due to manufacturing tolerances. It was sized to pass the ultimate load test under the most adverse size allowed under the tolerances. Odds are, it'll be a little stronger.
For comparison, spacecraft have (I think) an ultimate load of 110% of the max load. The margins are awfully thin, but they have little choice. If you really want a math heavy engineering job, design spacecraft.
BTW, the stress group signed off on the jackscrew size. If it had failed the ultimate load test, both them and I would have had a black eye. As it turned out, the test guys were embarrassed by their bent rig :-) and fortunately that wasn't really a problem.
One day, I got called into the stress group, where they told me they were unhappy with my parts. I asked why, they said there just barely strong enough for the ultimate load, only about 1% over. They said they'd feel more comfortable with 10% extra strength.
I said this was no coincidence, I used math to size the part to the load, rather than guessing at a size and checking to see if it was strong enough. The requirement was the ultimate load, which is 150% of the maximum load that could ever be expected.
I asserted that I designed to the design requirement, and an extra 10% would make it overweight. Brat that I was, I said if you guys were unhappy with the design requirement, increase it. They grudgingly signed off on it.
The reason it didn't break on the test stand is because all parts vary in size due to manufacturing tolerances. It was sized to pass the ultimate load test under the most adverse size allowed under the tolerances. Odds are, it'll be a little stronger.
For comparison, spacecraft have (I think) an ultimate load of 110% of the max load. The margins are awfully thin, but they have little choice. If you really want a math heavy engineering job, design spacecraft.
BTW, the stress group signed off on the jackscrew size. If it had failed the ultimate load test, both them and I would have had a black eye. As it turned out, the test guys were embarrassed by their bent rig :-) and fortunately that wasn't really a problem.
>They said they'd feel more comfortable with 10% extra strength.
Did they want the extra 10% buffer for any particular reason?
Reason I ask, I always agreed with your take on not over-designing, philosophically. I had a couple of professors who made a big deal about being conservative/ round-up on calculating design elements, but once you tally up the different loading cases, you shouldn't ever bump the total required strength (again) beyond whatever the required multiplier is.
However, when faced with real life projects, I learned fairly early to ignore that advise, mostly because of the risk of having to redesign due to a changed design requirement. Of course I've also never worked for a company as structured as one like Boeing, and I've also encountered LRFD 99% of the time over ASD.
It's one of those life lessons that's never really sat right with me, but I still consider to be the rational choice.
Did they want the extra 10% buffer for any particular reason?
Reason I ask, I always agreed with your take on not over-designing, philosophically. I had a couple of professors who made a big deal about being conservative/ round-up on calculating design elements, but once you tally up the different loading cases, you shouldn't ever bump the total required strength (again) beyond whatever the required multiplier is.
However, when faced with real life projects, I learned fairly early to ignore that advise, mostly because of the risk of having to redesign due to a changed design requirement. Of course I've also never worked for a company as structured as one like Boeing, and I've also encountered LRFD 99% of the time over ASD.
It's one of those life lessons that's never really sat right with me, but I still consider to be the rational choice.
> Did they want the extra 10% buffer for any particular reason?
They said they just were more comfortable with more margin. The stress group was an independent organization to avoid conflicts of interest with the design group. Our job was to design, their job was to verify. If parts broke, they got the black eye. If the airplane was overweight, design got the black eye. We both had to agree, and it was a system that worked well.
Most design engineers didn't work out the stresses themselves, they just hoped to pass the stress group. It was pass/fail for them. In my not so humble opinion, they were making overweight parts. I was interested in using math to sculpt perfect parts :-)
For example, the inside diameter of the jackscrew was specified to the ten-thousandth of an inch, something like 2.1834..2.2096. So I'd get the "why not make it a nice round 2.19..2.20?" I'd reply because if it came in at 2.205, it would get rejected, even though it was perfectly usable. And I got my way, because the jackscrew forging was a very, very expensive part and rejecting a usable part did not make anyone happy.
(Rejected expensive parts often got bounced back to engineering to find a way to salvage them. I just was doing the math in advance so they wouldn't have to.)
They said they just were more comfortable with more margin. The stress group was an independent organization to avoid conflicts of interest with the design group. Our job was to design, their job was to verify. If parts broke, they got the black eye. If the airplane was overweight, design got the black eye. We both had to agree, and it was a system that worked well.
Most design engineers didn't work out the stresses themselves, they just hoped to pass the stress group. It was pass/fail for them. In my not so humble opinion, they were making overweight parts. I was interested in using math to sculpt perfect parts :-)
For example, the inside diameter of the jackscrew was specified to the ten-thousandth of an inch, something like 2.1834..2.2096. So I'd get the "why not make it a nice round 2.19..2.20?" I'd reply because if it came in at 2.205, it would get rejected, even though it was perfectly usable. And I got my way, because the jackscrew forging was a very, very expensive part and rejecting a usable part did not make anyone happy.
(Rejected expensive parts often got bounced back to engineering to find a way to salvage them. I just was doing the math in advance so they wouldn't have to.)
That specification is to 2.5 micron accuracy. Surely the forging can't be made to that precision?
> Surely the forging can't be made to that precision?
It's forged slightly oversized, then machined down to spec.
Forgings are about 3x stronger than a casting, and are of a more consistent quality, which is why when I increased the HP for my Dodge, I spent the extra bucks to get forged spinning parts (usually they are cast).
It's forged slightly oversized, then machined down to spec.
Forgings are about 3x stronger than a casting, and are of a more consistent quality, which is why when I increased the HP for my Dodge, I spent the extra bucks to get forged spinning parts (usually they are cast).
The range is much larger: OP was just being very precise in expressing the range so the manufacturing process had some extra leeway.
I wonder what was measuring to that precision with such accuracy! It’s when I think about tolerances on the equipment that’s checking tolerances that I start getting dizzy and retreat to software for a bit.
2.5 micron is basically the metric value for a 'tenth', i.e. one ten-thousandths of an inch. A typical machine shop will usually work in tolerances of a 'thou' or two, but most are equipped to measure to tenths without too much fuss. Standard micrometers have a vernier that reads tenths, and tenths indicators aren't uncommon.
Going beyond that, to tens of millionths or sub-micron, is where things get nutty with special climate controlled rooms. Digital indicators can easily read with such precision, but controlling for factors like radiated body heat become important.
Reference measurement is usually done with gauge blocks and pins. The development and popularization of these sets is basically how mechanical parts became standardized.
If you're interested in that sort of thing - bootstrapping precision and the like - check out "The Foundations of Mechanical Accuracy".
Going beyond that, to tens of millionths or sub-micron, is where things get nutty with special climate controlled rooms. Digital indicators can easily read with such precision, but controlling for factors like radiated body heat become important.
Reference measurement is usually done with gauge blocks and pins. The development and popularization of these sets is basically how mechanical parts became standardized.
If you're interested in that sort of thing - bootstrapping precision and the like - check out "The Foundations of Mechanical Accuracy".
The precision (ability) of the machine rarely matches the precision of the measuring apparatus, if it's even part of the same equipment. And that's usually ok, even preferred, and cheaper.
If it's a rabbit hole you're interested in, then check out the history of geodesy / geodetic surveying & the design of mechanical / optical surveying equipment- especially theodolites & auto-levels (and even chronometers and astronomic observatories, if you want to go 4-dimensional).
It was the "industry" that had a large hand in innovating this technology, which led to the smaller versions used in manufacturing (made even more interesting due to the fact it was all funded to better artillery, and ultimately ballistic missle targeting, sans-GPS.)
I'd be happy to steer you in the right direction, if interested. It's a personal favorite.
If it's a rabbit hole you're interested in, then check out the history of geodesy / geodetic surveying & the design of mechanical / optical surveying equipment- especially theodolites & auto-levels (and even chronometers and astronomic observatories, if you want to go 4-dimensional).
It was the "industry" that had a large hand in innovating this technology, which led to the smaller versions used in manufacturing (made even more interesting due to the fact it was all funded to better artillery, and ultimately ballistic missle targeting, sans-GPS.)
I'd be happy to steer you in the right direction, if interested. It's a personal favorite.
Possibly a coordinate measuring machine (CMM) in an environmentally controlled environment, but even then it's coming awfully close to the capability limits
The spec is almost certainly for the machining after it's been forged.
I would have loved to take a field trip to Saginaw Gear and see all the various steps in its manufacture.
Like this but bigger.
https://www.youtube.com/watch?v=dzIsR4Mg158
"ball screw" and "lead screw" are your search terms. For aerospace it's gonna also be center drilled to save weight as well.
https://www.youtube.com/watch?v=dzIsR4Mg158
"ball screw" and "lead screw" are your search terms. For aerospace it's gonna also be center drilled to save weight as well.
The forged parts are likely machined (for better finish and tolerance).
I wonder if you guys all went on a field trip to watch The Wind Rises haha
Sometimes these factors of safety are matters of convention (like the discretion of a company of certifying engineer) and sometimes they are grounded in some safety standard.
For example, if you're testing the integrity of a pressure vessel, the standard is to test it to 110% the rated maximum allowable working pressure if the medium is a compressible fluid (like air) or 150% if it's a 'non-compressible' fluid (like water, although everything is compressible to a certain extent). This is because the compression of a fluid stores a lot more internal energy if suddenly released. (Don't quote me exactly on these numbers because it's been a looooong time since I've had my nose in ASME standards)
For example, if you're testing the integrity of a pressure vessel, the standard is to test it to 110% the rated maximum allowable working pressure if the medium is a compressible fluid (like air) or 150% if it's a 'non-compressible' fluid (like water, although everything is compressible to a certain extent). This is because the compression of a fluid stores a lot more internal energy if suddenly released. (Don't quote me exactly on these numbers because it's been a looooong time since I've had my nose in ASME standards)
I get factor of safety- (and phi etc for LRFD) what we're talking about is beyond the required factor of safety. OP designed the part using required multipliers, but the department checking the design wanted an extra 10% strength.
The point I was trying to get at is that in many cases (e.g., those not covered by an industry standard) there is no explicit “required” factor of safety. It’s left up to the discretion of the authority having jurisdiction. So while the design engineer may feel like a factor of safety of 2.0 is sufficient, the AHJ may “require” a 2.2 FOS to sign off
Thank you for sharing these stories, they’re amazing.
I'll add my thanks to the others - you must have (had?) a very interesting career.
Working on D is fun, too!
Thanks for the in-depth response! I think your response about increasing the design requirement was spot on. Maybe I'm a brat too. :P
Thanks for sharing! This was super interesting :-)
> I lost my fear of flying through working on the 757.
That's refreshing. I have a friend who worked on the A380 and she says she'll never set foot on one.
That's refreshing. I have a friend who worked on the A380 and she says she'll never set foot on one.
Same here. I know / worked with several engineers involved in the development of the Flight Controls of recent Airbus airliners and that often swore that they were going to avoid taking the model they were currently working on (usually based on some "critical" technical concern that turned out to be insignificant a few weeks later).
My answer was usually to mock them and say "so just because you are looking from too close and have lost perspective you prefer to fly an ageing aircraft or trust some random Boeing contractor more than yourself".
And fast forward ten years, the "deathtraps" they were working on - A340, A380 and A350 - turned out to be extremely safe (with fatality-free records).
My answer was usually to mock them and say "so just because you are looking from too close and have lost perspective you prefer to fly an ageing aircraft or trust some random Boeing contractor more than yourself".
And fast forward ten years, the "deathtraps" they were working on - A340, A380 and A350 - turned out to be extremely safe (with fatality-free records).
For what it's worth, I work with many people deeply involved in the A380 design from the beginning (and other Airbus aircraft), and they don't pass a chance to fly it.
The Air Force would send the chief mechanics up on check rides. It's a great way to ensure they did their job well :-)
Ouch!
Did she say why?
I have had this talk many times and it usually went something like: "You don't realize how serious it is. We discover issue#13270 during the validation of the FCDC. If it occurs after the primary flight computer had a hardware failure and the pilot is landing with heavy side winds and the thunder strikes, there is a heightened probability of hard landing. Most dangerous aircraft ever. By the way, this weekend I'm taking an Avro RJ100 to go to Brussels; no problem there."
This sent me down a rabbit hole. The RJ100 (BAe 146) can apparently be kitted to take off and land on gravel:
https://www.aviationpros.com/aircraft/commercial-airline/pre...
https://www.aviationpros.com/aircraft/commercial-airline/pre...
So can a 737:
http://www.b737.org.uk/unpavedstripkit.htm
http://www.b737.org.uk/unpavedstripkit.htm
The 737 was originally designed for short, unpaved runways, which would bring jet service to many otherwise inaccessible airports.
Sure, the older 737s. That's why most of the 737-200s still in service are up in Canada. The high bypass engines on the NGs and newer are too big to easily fit gravel kits on.
Do you have a recommended resource for reading more about the 757? I find it interesting but I’ve never dig deeper into it.
I don't know of any books about its development. Looking back I suppose I should have kept a diary. We weren't allowed to take materials home, so I have no documentation.
The 757 was the last airplane designed using paper drawings and wooden mockups. The end of an era :-) Some of the engineers still used slide rules. My lead engineer once said "let me show you how it's done" and pulled out a very nice slide rule in a leather pouch. I made a little show of blowing the dust off of it, and he laughed heartily. He started at Boeing on the B-47 design, and even he had already moved on to calculators.
But nobody used computers yet. I found a PDP-11 in a neighboring building and sweet talked the sysop into giving me an account on it. I'd write my own numerical analysis programs using Fortran IV.
My other lead was an old salt who told me he didn't trust computers, they always produced unreliable answers. But he was a good egg, and said he'd give me a chance. There was some long complex geometrical calculations to be done to prove the elevator linkage wouldn't bind up under load. The usual method was to use drafting tools to figure it out, and he put his best draftsman on the job. I wrote a program to figure it out, and came back with my column of numbers to 6 places. His draftsman compared it with his column, accurate to 4 places.
One of them was off. My lead said see, I told you computers were garbage. I asked the draftsman to recheck that one, and he did, and came back and said I was right.
Ever since then I got the calculation jobs, and my lead would defend me. One day, the CS dept head discovered I'd been stealing unauthorized time on the PDP-11, and I got in trouble. My lead went to bat for me, it went up 3 levels of management, and the top guy told the CS mucky-muck to piss off and give me whatever computer time I needed.
I was only the vanguard of what was to come in using computers to design airplanes.
My experience with that motivated me to ensure D had a first class foundation for numerical programming.
The 757 was the last airplane designed using paper drawings and wooden mockups. The end of an era :-) Some of the engineers still used slide rules. My lead engineer once said "let me show you how it's done" and pulled out a very nice slide rule in a leather pouch. I made a little show of blowing the dust off of it, and he laughed heartily. He started at Boeing on the B-47 design, and even he had already moved on to calculators.
But nobody used computers yet. I found a PDP-11 in a neighboring building and sweet talked the sysop into giving me an account on it. I'd write my own numerical analysis programs using Fortran IV.
My other lead was an old salt who told me he didn't trust computers, they always produced unreliable answers. But he was a good egg, and said he'd give me a chance. There was some long complex geometrical calculations to be done to prove the elevator linkage wouldn't bind up under load. The usual method was to use drafting tools to figure it out, and he put his best draftsman on the job. I wrote a program to figure it out, and came back with my column of numbers to 6 places. His draftsman compared it with his column, accurate to 4 places.
One of them was off. My lead said see, I told you computers were garbage. I asked the draftsman to recheck that one, and he did, and came back and said I was right.
Ever since then I got the calculation jobs, and my lead would defend me. One day, the CS dept head discovered I'd been stealing unauthorized time on the PDP-11, and I got in trouble. My lead went to bat for me, it went up 3 levels of management, and the top guy told the CS mucky-muck to piss off and give me whatever computer time I needed.
I was only the vanguard of what was to come in using computers to design airplanes.
My experience with that motivated me to ensure D had a first class foundation for numerical programming.
> Looking back I suppose I should have kept a diary.
I’m quite sure that if you started a blog today with the stories that you can remember, that you’d have a ton of HN’ers who would read it.
Thanks again - your posts are great to read!
I’m quite sure that if you started a blog today with the stories that you can remember, that you’d have a ton of HN’ers who would read it.
Thanks again - your posts are great to read!
> One day, the CS dept head discovered I'd
> been stealing unauthorized time on the
> PDP-11, and I got in trouble.
> Are you sure that was because you were designing airplanes on the hardware and not video games?
I didn't want the sysop who let me in to be sorry he did so. Besides, I was engrossed in my models.
When I got my own 11, I wrote a game for it:
https://github.com/DigitalMars/Empire-for-PDP-11
> I recognize your user name
Is that 11 still in operation? Wow! DEC sure makes a tank for a computer!
I didn't want the sysop who let me in to be sorry he did so. Besides, I was engrossed in my models.
When I got my own 11, I wrote a game for it:
https://github.com/DigitalMars/Empire-for-PDP-11
> I recognize your user name
Is that 11 still in operation? Wow! DEC sure makes a tank for a computer!
I'm not on that machine, I meant that I did recognize your name from the Empire game. DEC sure made tanks, but I doubt that particular tank is still treading.
Have a great week!
Have a great week!
Your story reminds me very much of a coworker of mine. He mentioned how they'd start an analysis job on it and get a printout of the results delivered to their desk later in the day by a messenger. What a difference.
The nice thing about the 11 was it was an interactive system with a terminal, not one where you submitted jobs on a card deck. The "computer room" was air conditioned with a false floor under which ran cables and the cooling system. There was a line printer to get the results instantly. There was a coded lock on the door, which is why I needed the sysop to give me access.
I later bought a Heathkit H-11 so I could have my very own PDP-11. You can see it on my twitter picture https://twitter.com/WalterBright
I later bought a Heathkit H-11 so I could have my very own PDP-11. You can see it on my twitter picture https://twitter.com/WalterBright
The late Colonel John Boyd also chose to steal computer time as part of doing the work to develop his “Energy Maneuverability Theory” for developing USAF dogfighting strategies.
I’d say you’re in decent company.
:-)
I’d say you’re in decent company.
:-)
I've read Boyd's biography (well worth reading). I couldn't possibly compare to that man and his contributions.
The 737-MAX is the plane equivalent of Windows XP Service Pack 8.
> JetBlue is among airlines planning to use the [AirBus A321LR] on routes across the pond, serving Western Europe from New York and Boston.
This has to be a gut punch for Southwest, who has famously relied only on the 737. They're close to hitting their ceiling on domestic expansion with the 737 and can't compete on US-EU routes because of their fleet.
I like that the author points out the realities of modern 737 performance - just because it _can_ reach coast to coast destinations doesn't mean it _should_.
Thats not to say that the 757 is perfect. From what I've heard, maintenance is significantly more complex than the 737. And as the article pointed out, it takes way too long to board/deplane for the short hops that the 737 dominates now.
> JetBlue is among airlines planning to use the [AirBus A321LR] on routes across the pond, serving Western Europe from New York and Boston.
This has to be a gut punch for Southwest, who has famously relied only on the 737. They're close to hitting their ceiling on domestic expansion with the 737 and can't compete on US-EU routes because of their fleet.
I like that the author points out the realities of modern 737 performance - just because it _can_ reach coast to coast destinations doesn't mean it _should_.
Thats not to say that the 757 is perfect. From what I've heard, maintenance is significantly more complex than the 737. And as the article pointed out, it takes way too long to board/deplane for the short hops that the 737 dominates now.
Southwest as far as I'm aware had shown no interest in transatlantic routes, nor do I think they've hit their domestic growth limits - there are still lots of places they don't fly.
They fly to Hawaii now, as well as Central America and the Carib with their AirTran acquisition. As you said, lots of places to fly still.
Once Southwest gets over the hurdle of flying something other than 737s, it'll have transatlantic ambitions.
But flying a single kind of plane has a lot of advantages, doesn't it?
It seems that switching to a new plane would mean a drastic economic change.
So the transatlantic ambitions should be a cause to go past that, rather than a side effect.
It seems that switching to a new plane would mean a drastic economic change.
So the transatlantic ambitions should be a cause to go past that, rather than a side effect.
Having a single source for planes also has disadvantages, as the recent fiasco demonstrates.
The CEO is on record saying that they will be evaluating having a second source of planes next year:
https://theaircurrent.com/airlines/southwest-wants-a-small-a...
The CEO is on record saying that they will be evaluating having a second source of planes next year:
https://theaircurrent.com/airlines/southwest-wants-a-small-a...
Their service to SEA is terrible. Competition here would be nice to CA/AZ but Delta is very reliable and inexpensive (plus it flies the superior Airbus equipment) to Phoenix, so that's a tough route to win.
Their service to SEA is terrible. Competition here would be nice to CA/AZ but Delta is very reliable and inexpensive (plus it flies the superior Airbus equipment) to Phoenix, so that's a tough route to win.
Delta flies pretty much everything including the 737.
Delta flies pretty much everything including the 737.
And given as choice, out of Seattle, I'm more likely to fly Alaska, as their equipment is considerably newer than Delta.
Depends on the route. The last time I flew Alaska to SEA was on a 737-400 a couple years ago. They've since been retired, but their current interiors are rather sterile and have those awful slimline seats. Meanwhile I think Delta will be bringing the A220 to Seattle.
Delta also flies a lot of regional carriers to SEA (and both Compass and SkyWest are pretty mediocre out of SEA). I'll take the 2x2 seating of a CRJ/ERJ over a 737 (or the Dash-8s) any day, especially Delta's newer low density layout. The Dash 8 isn't bad for a turboprop, but it's still a turboprop.
Delta also flies a lot of regional carriers to SEA (and both Compass and SkyWest are pretty mediocre out of SEA). I'll take the 2x2 seating of a CRJ/ERJ over a 737 (or the Dash-8s) any day, especially Delta's newer low density layout. The Dash 8 isn't bad for a turboprop, but it's still a turboprop.
> Meanwhile I think Delta will be bringing the A220 to Seattle
They‘re on the SEA-SJC route now, at the least. Great planes.
They‘re on the SEA-SJC route now, at the least. Great planes.
I'd rather fly Alaska most of the time too, but lock-in to Delta frequent flier miles being what they are...
I agree - meant to say that most of the SEA-PHX legs have been route changed to Airbus lately, which has been nice.
I agree - meant to say that most of the SEA-PHX legs have been route changed to Airbus lately, which has been nice.
If you think they're nice, you should've seen them with the Virgin America interior.
As someone flying out of the Bay Area, Alaska just isn't that compelling. Their route network is smaller than the big 3 and their product isn't well differentiated from the rest. I've heard good things about their customer service, but so far Delta has done right by me when either I or they have screwed up.
If you think they're nice, you should've seen them with the Virgin America interior.
As someone flying out of the Bay Area, Alaska just isn't that compelling. Their route network is smaller than the big 3 and their product isn't well differentiated from the rest. I've heard good things about their customer service, but so far Delta has done right by me when either I or they have screwed up.
More like Windows 95 Service Pack 15 :)
> The 737-MAX is the plane equivalent of Windows XP Service Pack 8.
If I have an important device that I'm not attaching to a network, that sounds like a good thing. It may not have every feature but it's very stable and efficient.
If I have an important device that I'm not attaching to a network, that sounds like a good thing. It may not have every feature but it's very stable and efficient.
Except that’s the opposite of how the 737-Max actually is. It’s more like they kept bolting on bigger and bigger engines until it had totally different aerodynamics.
Yeah, that doesn't sound like an XP service pack at all.
It's amusing that I got downvotes for someone else's analogy being bad.
It's amusing that I got downvotes for someone else's analogy being bad.
It’s a bad analogy but maybe responding to the analogy in a way that doesn’t apply to the airplane problem came across as confusing and irrelevant.
Personally I don't think it's irrelevant to try to cut off an unhelpful analogy, those things sometimes act like black holes. But point taken.
Nah I get that, it was just ambiguous whether you were cutting it off or falling into the black hole, but maybe that’s just me :)
The black hole would be trying to elaborate a whole lot on top of a completely broken foundation, or trying to fix the analogy in intense detail when you should start from scratch, etc.
I just said one line about how that analogy didn't fit.
I just said one line about how that analogy didn't fit.
Theire should be after accident reclassifications to new planes.
What makes you think there isn’t a review process?
There is a process for “special certification review”, some of those end with changes (typically airworthiness directives); others validate the airplane as meeting certification and safe.
Lear 60, MU-2, DC-10, MD-11, ATR-72, R22/R44 helicopters, Piper Malibu, CE-441, and Bonanza have all undergone the SCR process and continue to fly having been validated as safe/conforming (some with changes to airframe or procedures)
To my knowledge, only the DC-6 and Constellation had their type certification revoked after in-service accidents.
There is a process for “special certification review”, some of those end with changes (typically airworthiness directives); others validate the airplane as meeting certification and safe.
Lear 60, MU-2, DC-10, MD-11, ATR-72, R22/R44 helicopters, Piper Malibu, CE-441, and Bonanza have all undergone the SCR process and continue to fly having been validated as safe/conforming (some with changes to airframe or procedures)
To my knowledge, only the DC-6 and Constellation had their type certification revoked after in-service accidents.
Isn't this exactly what technical debt is? The term originated in software engineering, but it seems to be exactly what Boeing has if we transfer the terminology into aerospace.
> is a concept that reflects the implied cost of additional rework caused by choosing an easy (limited) solution now instead of using a better approach that would take longer
737 rated pilots are abundant, production lines are ready and paid for and orders come in as long as the product works. There is huge incentive to do just small fixes if you can't see technical debt in the books. When it shows up in the bottom line company is already paying interest.
> is a concept that reflects the implied cost of additional rework caused by choosing an easy (limited) solution now instead of using a better approach that would take longer
737 rated pilots are abundant, production lines are ready and paid for and orders come in as long as the product works. There is huge incentive to do just small fixes if you can't see technical debt in the books. When it shows up in the bottom line company is already paying interest.
The points guy is a terrible source largely full of mistakes and poor information.
For instance: “ If built, the 797 would bridge the range and capacity gap between the narrowbody 737 family and the much larger 787 and 777 families — a slot occupied by the now-geriatric 757 and 767.”
The 787 and the 767 are the same size to a rounding error. The 787 is basically a drop in replacement for the 767 but much more efficient.
And further, the 737MAX and the A321LR (and A320neo) and even the A220 are designed to replace the role of the 757 in air travel. The US market wants smaller aircraft that are more efficient and fly longer range to open up more frequencies. They’re getting them.
> “ I may be biased, since I fly it, but you might undoubtedly call it the most versatile jetliner Boeing has ever built. It’s a medium-capacity, high-performing plane able to turn a profit on both short and longer-haul routes”
Even a quick perusal down Wikipedia would tell you the 757s are incredibly inefficient aircraft, getting a second wind a cargo haulers due to their way outsized power to weight ratio. And even with all that they can’t make regularly scheduled east coast transatlantic flights without often stopping along the way if there are temperatures or headwinds.
As for domestic travel the sheer inefficiency of the planes makes them a poor contender. Really only the full-transcon corridor made any sense at all and even those are being replaced. JetBlue went all A320. They’re by no means “able to turn a profit on short and medium haul flying” solely by virtue of them being scheduled. They’re often flying them for utilization reasons. Can you even call any of this flying “profitable” when American had a 3% margin last quarter across their entire route network, lost money on domestic and made it up on international?
The 737 will absolutely take the place of the 757, and already was scheduled to prior to the MCAS issues coming to light.
For instance: “ If built, the 797 would bridge the range and capacity gap between the narrowbody 737 family and the much larger 787 and 777 families — a slot occupied by the now-geriatric 757 and 767.”
The 787 and the 767 are the same size to a rounding error. The 787 is basically a drop in replacement for the 767 but much more efficient.
And further, the 737MAX and the A321LR (and A320neo) and even the A220 are designed to replace the role of the 757 in air travel. The US market wants smaller aircraft that are more efficient and fly longer range to open up more frequencies. They’re getting them.
> “ I may be biased, since I fly it, but you might undoubtedly call it the most versatile jetliner Boeing has ever built. It’s a medium-capacity, high-performing plane able to turn a profit on both short and longer-haul routes”
Even a quick perusal down Wikipedia would tell you the 757s are incredibly inefficient aircraft, getting a second wind a cargo haulers due to their way outsized power to weight ratio. And even with all that they can’t make regularly scheduled east coast transatlantic flights without often stopping along the way if there are temperatures or headwinds.
As for domestic travel the sheer inefficiency of the planes makes them a poor contender. Really only the full-transcon corridor made any sense at all and even those are being replaced. JetBlue went all A320. They’re by no means “able to turn a profit on short and medium haul flying” solely by virtue of them being scheduled. They’re often flying them for utilization reasons. Can you even call any of this flying “profitable” when American had a 3% margin last quarter across their entire route network, lost money on domestic and made it up on international?
The 737 will absolutely take the place of the 757, and already was scheduled to prior to the MCAS issues coming to light.
> the 757s are incredibly inefficient aircraft
Ironic considering the genesis of the 757 was a new wing and new engines that produced a 35% improvement on fuel efficiency over the 727 it replaced.
Ironic considering the genesis of the 757 was a new wing and new engines that produced a 35% improvement on fuel efficiency over the 727 it replaced.
Oh definitely but that was almost 40 years ago (launched in 1981, designed even earlier). Progress is a wonderful thing!
Never understood why the 757 wasn't more popular?? It had the best performance in its class while still being economical. Maybe back in its day there was too much overlap between it and the 767, but from talking to pilots who have flown it, the 757 handled like a fighter jet, and passengers seemed to love it too.
Never understood why the 757 wasn't more popular?? It had the best performance in its class while still being economical. Maybe back in its day there was too much overlap between it and the 767, but from talking to pilots who have flown it, the 757 handled like a fighter jet, and passengers seemed to love it too.
It's too much plane for most use cases — too heavy and too thirsty.
It's too much plane for most use cases — too heavy and too thirsty.
If the 757 were still in production today, it would still sell OK.
There is now a big demand for aircraft that size for certain routes (US transcontinental, and second-city Transatlantic, especially the transatlantic)
What happened is that laws changed to allow twin-engine aircraft to fly routes much farther from the nearest alternate landing site, making 757s suddenly great vehicles for Transatlantic flights between second cities. Of course, this happened shortly after production of the 757 ended.
There is now a big demand for aircraft that size for certain routes (US transcontinental, and second-city Transatlantic, especially the transatlantic)
What happened is that laws changed to allow twin-engine aircraft to fly routes much farther from the nearest alternate landing site, making 757s suddenly great vehicles for Transatlantic flights between second cities. Of course, this happened shortly after production of the 757 ended.
If the 757 were still in production today, it would still sell OK.
ETOPS helped the 757 into the international role sure, but the 737 and A320 are more fuel efficient and benefit from being able to share crew.
ETOPS helped the 757 into the international role sure, but the 737 and A320 are more fuel efficient and benefit from being able to share crew.
757-200 has about 800 nautical miles more range than the longest-range 737NG.
737-900er, the longest-range 737NG only has 3000 nautical miles of range, which is just enough for TATL flights. The 757-200's slightly longer range opens up many additional city pairs without having to upgauge to a 767.
Of course, now that Boeing has lost a couple of years due to massive failures (like the 737-MAX), Airbus has had time to catch up -- and the A320neo-based A321-XLR finally surpasses the 757-200 in this space.
However, the XLR seats about 70 fewer passengers than the 757, so the 757 will probably still live on for a little while longer.
If Boeing hadn't killed the 757, and then immediately start sucking, there might've been a refresh to a 757 MAX-like aircraft that sat 225-290, had a 4500nmi range and was efficient. But, you know, we got the real timeline instead.
737-900er, the longest-range 737NG only has 3000 nautical miles of range, which is just enough for TATL flights. The 757-200's slightly longer range opens up many additional city pairs without having to upgauge to a 767.
Of course, now that Boeing has lost a couple of years due to massive failures (like the 737-MAX), Airbus has had time to catch up -- and the A320neo-based A321-XLR finally surpasses the 757-200 in this space.
However, the XLR seats about 70 fewer passengers than the 757, so the 757 will probably still live on for a little while longer.
If Boeing hadn't killed the 757, and then immediately start sucking, there might've been a refresh to a 757 MAX-like aircraft that sat 225-290, had a 4500nmi range and was efficient. But, you know, we got the real timeline instead.
737-900er, the longest-range 737NG only has 3000 nautical miles of range, which is just enough for TATL flights. The 757-200's slightly longer range opens up many additional city pairs without having to upgauge to a 767.
The 737-900ER doesn't have the range of the 757 but it will use less fuel on the routes both can do.
However, the XLR seats about 70 fewer passengers than the 757, so the 757 will probably still live on for a little while longer.
For airlines that already have 757s, maybe. The XLR and 757-200 both offer nearly identical seating (with the nod going to the XLR in one class config) and range. The 757-300 can seat about 40 more in one class config, but you take a pretty hefty range penalty. Ultimately the XLR is pretty much the direct replacement for the 757.
The XLR (and 900ER and MAX) also have one big advantage that no revamp of the 757 will offer: commonality. You can share flight and cabin crew between the 318/319/320/321 (CEO and NEO) and between the 600/700/800/900/900ER (NG) and 7/8/9/10 (MAX).
The Airbus lineup (320/330) is further compelling because going between the narrow and widebody product requires relatively little training.
If Boeing hadn't killed the 757, and then immediately start sucking, there might've been a refresh to a 757 MAX-like aircraft that sat 225-290, had a 4500nmi range and was efficient. But, you know, we got the real timeline instead.
Boeing killed the 757 because nobody bought it. Same with the 767. In fact the only reason the 767 line is still open is because the USAF bought the KC-46. Meanwhile 757 operators like Iceland Air were moving away from the 757 to the MAX. The 757 was a great plane, but it was the wrong product at the wrong time.
Personally I think the 737 ought to die. I don't like it as a passenger, and I can't imagine it being fun in the legendarily noisy and cramped cockpit on a long haul flight.
The 737-900ER doesn't have the range of the 757 but it will use less fuel on the routes both can do.
However, the XLR seats about 70 fewer passengers than the 757, so the 757 will probably still live on for a little while longer.
For airlines that already have 757s, maybe. The XLR and 757-200 both offer nearly identical seating (with the nod going to the XLR in one class config) and range. The 757-300 can seat about 40 more in one class config, but you take a pretty hefty range penalty. Ultimately the XLR is pretty much the direct replacement for the 757.
The XLR (and 900ER and MAX) also have one big advantage that no revamp of the 757 will offer: commonality. You can share flight and cabin crew between the 318/319/320/321 (CEO and NEO) and between the 600/700/800/900/900ER (NG) and 7/8/9/10 (MAX).
The Airbus lineup (320/330) is further compelling because going between the narrow and widebody product requires relatively little training.
If Boeing hadn't killed the 757, and then immediately start sucking, there might've been a refresh to a 757 MAX-like aircraft that sat 225-290, had a 4500nmi range and was efficient. But, you know, we got the real timeline instead.
Boeing killed the 757 because nobody bought it. Same with the 767. In fact the only reason the 767 line is still open is because the USAF bought the KC-46. Meanwhile 757 operators like Iceland Air were moving away from the 757 to the MAX. The 757 was a great plane, but it was the wrong product at the wrong time.
Personally I think the 737 ought to die. I don't like it as a passenger, and I can't imagine it being fun in the legendarily noisy and cramped cockpit on a long haul flight.
On the XLR, you're right. I was misreading Wikipedia's capacity tables -- the XLR and the -200 are virtually identical in passenger capacity
It's a narrow body. They went out of fashion.
737s are narrow body, aren't they? And they're still quite popular.
The 757 was too big for what airlines wanted out of narrow bodies. Now it’s the same size as a 737 MAX 10.
The 757 is similar to the 737-MAX10 except for that nasty MCAS crashing business.
It is probably infeasible to make a wide body aircraft the size of a 737 - if they could, they would. The ergonomics (and economics) of twin aisles is vastly better than single aisle planes.
Boeing/Aurora are kinda trying that with the D8 (aka double bubble). It’s not exactly the same since it is basically two circles next to each other rather than one large one, but it will be twin aisle.
The D8 is one of the cooler projects right now, in my opinion. It isn’t too radical like many designs, but it would dramatically lower fuel consumption (50-70%), offer dual aisle boarding on a smaller craft, and a lot less noise. All in a package that doesn’t have too many unknowns from an aeronautics perspective.
The D8 is one of the cooler projects right now, in my opinion. It isn’t too radical like many designs, but it would dramatically lower fuel consumption (50-70%), offer dual aisle boarding on a smaller craft, and a lot less noise. All in a package that doesn’t have too many unknowns from an aeronautics perspective.
Boeing has botched this so badly that the replacement for the B-737 will probably be the Comac C919. It's not clear how good an aircraft it will be, but the financing is very favorable.
[1] https://en.wikipedia.org/wiki/Comac_C919
[1] https://en.wikipedia.org/wiki/Comac_C919
> Boeing has botched this so badly that the replacement for the 737 will probably be
It will definitely be the A320 family, which has none of these problems, comes in sensible size variants already, is used extensively every day around the world, is price comparable, and isn't going to spook Western consumers in the same way that a Chinese plane will.
It will definitely be the A320 family, which has none of these problems, comes in sensible size variants already, is used extensively every day around the world, is price comparable, and isn't going to spook Western consumers in the same way that a Chinese plane will.
No way man. Comac is decades away from an aircraft that will be competitive outside of China.
Is there a way to select for the aircraft when booking a flight?
Price, flight times, and minimal number of connections are the main focus; but is there a website that can add in aircraft type?
I realise types can be swapped, but with historical data there should be very high probability of prediction of aircraft type at booking.
I flew a 757 back in the 1980s and have fond memories of it. This article made me realise that a spate of flying in 737s might have been what put me off flying for so long.
Price, flight times, and minimal number of connections are the main focus; but is there a website that can add in aircraft type?
I realise types can be swapped, but with historical data there should be very high probability of prediction of aircraft type at booking.
I flew a 757 back in the 1980s and have fond memories of it. This article made me realise that a spate of flying in 737s might have been what put me off flying for so long.
Most airline websites and search engines will show you which type of aircraft a flight is on in the results. Alternatively, Google Flights or ITA Matrix can show you. You don't always get to find out easily which variant of an aircraft it is, e.g. a 757-200 vs. a 757-300 might both show as "757."
So there’s a gap in the market if you want to be able to filter by aircraft.
I can imagine adding another dimension for searching flights could have an impact on usability though.
I can imagine adding another dimension for searching flights could have an impact on usability though.
Or it could be an opportunity for Airbus to publish a “Fly Airbus” website. I think they’ve already done it in the first years of the A380. That way the plane brand filter is embedded before even starting the search.
ITA Matrix is my favorite powerful flight search engine. It lets you filter by aircraft, among many other things. You have to learn what essentially amounts to a really obscure query language to use it effectively.
Google Flights uses ITA Matrix tech (bought by Google a few years ago) and it even gives you a link to buy tickets straight from the airline. Has pretty much the same usability features of ITA Matrix and none of the cruft of Orbitz et. al.; highly recommend it.
Some power user features of ITA aren't available on Google Flights still - for example, it lets you construct specific weird routings or layovers that Google will often optimize away. For instance, if you want a 24 hour layover in a city, or if you want to fly a less efficient direction to your destination to build mileage, or whatever.
You can use bookwithmatrix.com, though, which parses the output and will generate a ticket for booking on an online travel agency like Expedia.
You can use bookwithmatrix.com, though, which parses the output and will generate a ticket for booking on an online travel agency like Expedia.
Thanks for the recommendation! I hadn't heard of it bookwithmatrix.com.
I haven't seen a search filter for that but you could manually check the probable aircraft on SeatGuru once you find out the flight number from the airline's website.
Some airlines only fly single types of plane (eg. Easyjet now only flies Airbus A32x) so that would be one way to choose the plane.
Airlines shuffle planes constantly to deal with changes in demand, maintenance, etc.
Even if you knew what plane they're planning on flying when you bought the ticket, the plane that rolls onto the gate might still end up being a different one.
Even if you knew what plane they're planning on flying when you bought the ticket, the plane that rolls onto the gate might still end up being a different one.
Google Flights (and click through to the carrier’s site) has been pretty accurate for me. Only one time VA swapped a B787 for an A340 on my flight from LHR to JFK.
I asked the attendant and they explained that they were having some issues with the B787.
I asked the attendant and they explained that they were having some issues with the B787.
I am sure there will be all sorts of (correct) actuarial arguments that driving my car to work is more deadly than flying in the v2 737, but I still don't want to ever fly in a 737. It's got the mark of Cain at this point. I doubt I'm the only one that feels that way.
As I understand it, all 737s pre-MAX are fine; you want to avoid the MAX planes because of MCAS and the new engine placement.
As I understand it, all 737s pre-MAX are fine; you want to avoid the MAX planes because of MCAS and the new engine placement.
Yeah, just don't pay too much attention to the structural problems that Boeing is having with the 737 NG (cracked pickle forks). The inspection threshold keeps getting lower and the scope of the inspections keeps growing.
Yeah, just don't pay too much attention to the structural problems that Boeing is having with the 737 NG (cracked pickle forks). The inspection threshold keeps getting lower and the scope of the inspections keeps growing.
What a branding disaster, tack on the name of reliable series of crafts to a flying suicide machine and destroy the whole line.
I'm sure many customers will avoid 737s in general due to confusion.
I'm sure many customers will avoid 737s in general due to confusion.
Branding is like leverage. There's a downside that goes with the upside.
This will be such a confusion though. I’m reminded of my girlfriend who is not interested in airplanes and thinks all airplanes that start and end with a 7 are affected.
Planes are so ungodly safe that two crashes of the same model within a year of each other is an unprecedented scandal that would bankrupt the company were it not for it being a national strategic asset. We could only dream of road safety being held to such a standard. Flying is so much safer than driving it’s a marvel that anyone steps foot in a car at all... fun fact, flying is even safer than trains by a factor of four (!!), but I have friends who refuse to fly at all because of the possibility of their plane crashing and instead drive across the country to travel.
This article raises an interesting point in the 737 MAX discussions. Far too much the press coverage about the MAX has concentrated on whether the MAX can be made to fly safely - which I think it can be, but not, whether it is actually the right design for the tasks it is meant to do.
And it does not surprise that stretching a smaller design wouldn't do the trick so well.
I am not an aviation expert, so the article was a bit short on details which make the 757 better than the 737 MAX, but I assume it is the wider body and probably better sized wings etc.?
I am not an aviation expert, so the article was a bit short on details which make the 757 better than the 737 MAX, but I assume it is the wider body and probably better sized wings etc.?
707, 727, 737, and 757 all have the exact same cross section. One of the advantages of the 757 is that it sits higher off the ground and can accommodate the large engines necessary for a longer fuselage. More generally, 757 is designed to be longer, with larger engines and wings, and higher fuel capacity. 737 had to have these features bolted on as it was stretched, fitted with higher bypass (more fuel efficient) engines, and given larger wings and fuel capacity.
321LR will be very very successful if Boeing decides to scrap the 797 project.
> What would it be like on the westbound leg, I wondered — a longer flight, from a shorter runway, in the face of winter headwinds?
Wouldn't colder (denser) air and a headwind make the plane require less runway?
Wouldn't colder (denser) air and a headwind make the plane require less runway?
The author isn’t worried about the takeoff speed in that quote; he’s thinking about the increased duration of the flight as stiff winter headwinds (at cruising altitude) decrease the aircraft’s groundspeed.
Prevailing surface wind direction doesn’t vary much with season.
Prevailing surface wind direction doesn’t vary much with season.
A longer flight against with headwinds will require more fuel. Taking off with more fuel from a shorter runway will require the pilot to inflict even more bare-knuckling violence on the passengers.
I think he is referring to the jet stream at altitude, which is stronger during the winter.
I always like flying on a 757 because of the middle-ish door position. It breaks up the interior and makes boarding and deplaning more pleasant.
I far prefer the MD-80/MD-90/717 to the 737. The rear mounted engines make most seats (except the very back) far quieter and landings always seem smoother. Obviously they’re a smaller plane than contemporary 737s, but it’s still far more comfortable than the cramped conditions of the 737.
I far prefer the MD-80/MD-90/717 to the 737. The rear mounted engines make most seats (except the very back) far quieter and landings always seem smoother. Obviously they’re a smaller plane than contemporary 737s, but it’s still far more comfortable than the cramped conditions of the 737.
Will not touch technical side of plane. I am not so proficient in this field, but it’s one of the best looking passenger jet what humankind have designed. Now only cseries/a220 have done it rigth
737 < 757! The argument holds!
well, one's a narrowbody and the other a widebody with much higher PAX, so didn't really thing this was a point that needed to be made...
The 737 and 757 have identically sized fuselages. In fact, they are both basically the same fuselage as the original 707.
The 737 max is what happens when the bean counters are in control of an engineering firm.
The bean counters will always be there. Alternatively, one can think of the 737 MAX (and prior new 737 models) as an example of regulation imposing perverse incentives. ( https://en.wikipedia.org/wiki/Type_certificate )
Interesting point, but what would be the alternative? Are you really suggesting that pilots should be able to switch from e.g. the 737 to the A320 without any kind of additional training?
The alternative is that manufacturers shouldn't be allowed to impose new underlying systems to manage undesirable flight handling characteristics without briefing pilots about them and without breaking type certification.
the default should be that if the flight handling characteristics of the airframe itself inherently are not the same then it doesn't get type certification, and you should have to prove why your tweaks make it OK.
the default should be that if the flight handling characteristics of the airframe itself inherently are not the same then it doesn't get type certification, and you should have to prove why your tweaks make it OK.
Type certificates are not about pilots; they're about airframes. Maybe skim the link?
> A type certificate signifies the airworthiness of a particular category of aircraft, according to its manufacturing design (‘type’). It confirms that the aircraft is manufactured according to an approved design, and that the design ensures compliance with airworthiness requirements.
And to be clear, since it seems my comment was also not totally clear: I'm not saying aircraft regulation / Type Certification is bad in general. Just that this particular implementation currently has unintended perverse incentives which lead to the 737 MAX.
> A type certificate signifies the airworthiness of a particular category of aircraft, according to its manufacturing design (‘type’). It confirms that the aircraft is manufactured according to an approved design, and that the design ensures compliance with airworthiness requirements.
And to be clear, since it seems my comment was also not totally clear: I'm not saying aircraft regulation / Type Certification is bad in general. Just that this particular implementation currently has unintended perverse incentives which lead to the 737 MAX.
A pilot is qualified ("type rated") to fly planes of a given type certificate, so it's not helpful to say that type certificates are not about pilots. Having that belief causes you to miss out on fully understanding the situation.
I wouldn't call this a perverse or unexpected incentive either. It's very straightforward: there is regulation saying you can't keep the same type certificate if the plane flies differently enough to demand pilot retraining. The regulation is good and the consequences of following the regulation correctly are good, unlike in actual perverse incentive situations.
Boeing didn't want to comply with the regulation so they lied about how the plane worked and then hundreds of people died.
That's not an example of a perverse incentive of regulation: it's an example of dishonestly evading regulation, hopefully criminally so.
I wouldn't call this a perverse or unexpected incentive either. It's very straightforward: there is regulation saying you can't keep the same type certificate if the plane flies differently enough to demand pilot retraining. The regulation is good and the consequences of following the regulation correctly are good, unlike in actual perverse incentive situations.
Boeing didn't want to comply with the regulation so they lied about how the plane worked and then hundreds of people died.
That's not an example of a perverse incentive of regulation: it's an example of dishonestly evading regulation, hopefully criminally so.
> A pilot is qualified ("type rated") to fly planes of a given type certificate, so it's not helpful to say that type certificates are not about pilots.
Eh. The relationship here is between the manufacturer and the FAA. That the regulation is tangentially related to pilots is moot to the point.
> It's very straightforward: there is regulation saying you can't keep the same type certificate if the plane flies differently enough to demand pilot retraining. The regulation is good
I agree!
> and the consequences of following the regulation correctly are good
Mostly true!
> Boeing didn't want to comply with the regulation
This was (arguably) an outcome, but I don't believe it was the goal. I.e., Boeing would love to comply with this regulation in the magical hypothetical where it cost them nothing to do so. They're not comical villains.
The problem with this simplistic summary you've provided is that qualifying a new type certificate is extremely costly. Convincing the FAA your new aircraft is actually just a modified version of an existing type certificate (whether or not that is true) is much less costly (and given how much of the 1960s airframe is still being used in the MAX to keep that type certificate, it's even plausibly reasonable to consider it like earlier extensions to the cert).
So, long story short, there is a direct financial motivation for Boeing to skirt the rules and pretend new products are just another modified 737. That is exactly the perverse incentive I am highlighting.
> That's not an example of a perverse incentive of regulation: it's an example of dishonestly evading regulation, hopefully criminally so.
I think you mostly missed the point. Regulations with mostly good consequences can still create perverse incentives in some areas and positive incentives in others.
Eh. The relationship here is between the manufacturer and the FAA. That the regulation is tangentially related to pilots is moot to the point.
> It's very straightforward: there is regulation saying you can't keep the same type certificate if the plane flies differently enough to demand pilot retraining. The regulation is good
I agree!
> and the consequences of following the regulation correctly are good
Mostly true!
> Boeing didn't want to comply with the regulation
This was (arguably) an outcome, but I don't believe it was the goal. I.e., Boeing would love to comply with this regulation in the magical hypothetical where it cost them nothing to do so. They're not comical villains.
The problem with this simplistic summary you've provided is that qualifying a new type certificate is extremely costly. Convincing the FAA your new aircraft is actually just a modified version of an existing type certificate (whether or not that is true) is much less costly (and given how much of the 1960s airframe is still being used in the MAX to keep that type certificate, it's even plausibly reasonable to consider it like earlier extensions to the cert).
So, long story short, there is a direct financial motivation for Boeing to skirt the rules and pretend new products are just another modified 737. That is exactly the perverse incentive I am highlighting.
> That's not an example of a perverse incentive of regulation: it's an example of dishonestly evading regulation, hopefully criminally so.
I think you mostly missed the point. Regulations with mostly good consequences can still create perverse incentives in some areas and positive incentives in others.
The problem with this simplistic summary you've provided is that qualifying a new type certificate is extremely costly.
Yes but you're missing that there are two sets of costs: the recertification cost for Boeing, and the retraining costs for their customers, the airlines. Boeing didn't want to pay and it didn't want to tell its customers that there was this additional cost and risk losing some sales.
Yes but you're missing that there are two sets of costs: the recertification cost for Boeing, and the retraining costs for their customers, the airlines. Boeing didn't want to pay and it didn't want to tell its customers that there was this additional cost and risk losing some sales.
Cool, I agree with most of that. It just sounds like I think Boeing has behaved closer to comical villains than you do! I don't think some jail time for executives would be an overreaction.
Pilots are trained to operate particular models too.
I'm generally blown away at the audacity people have to suggest casually changing any FAA regulation, considering how good they are at their jobs...
I don't see how you parse that out of my comment without some extremely uncharitable interpretation. I haven't suggested any particular change, nor that any particular change be carried out "casually," without due consideration.
You were being uncharitable, why are you surprised it was interpreted that way?
Well, clearly they didn't do their job that well in this case
Boeing fucked up, not the FAA. The FAA is the one preventing Boeing from flying these planes because they're not safe!
Erm, it's pretty obvious something was wrong at the FAA, in that it seems fairly clear they let Boeing dictate terms to them on multiple occasions, and effectively overrule them.
https://www.seattletimes.com/business/boeing-aerospace/new-q...
Also, the FAA were the last aviation regulator to ground the MAX.
https://www.seattletimes.com/business/boeing-aerospace/new-q...
Also, the FAA were the last aviation regulator to ground the MAX.
The FAA's goal is to prevent aircraft related accidents. While you may not agree about the sharpness of their pencils or the color of their uniforms or some other tangential nonsense, flying is insanely safe in America because of them.
They're so good at their jobs, you should be asking what they know that you don't when they make decisions, not trying to correct them.
They're so good at their jobs, you should be asking what they know that you don't when they make decisions, not trying to correct them.
Historically, yes. There was a reason previously the CAA and EASA were historically happy accept the FAA's certification for new aircraft, on the assumption the FAA were very good at its job.
That no longer seems to be the case (given the fact that EASA now want to have their pilots fly the MAX before it returns to service), and there's well documented evidence (many news articles over the past few months talk about this) showing that over the past 10 years, the FAA's budget was drastically cut, forcing them to effectively outsource certification in part to Boeing to "self-certify".
That no longer seems to be the case (given the fact that EASA now want to have their pilots fly the MAX before it returns to service), and there's well documented evidence (many news articles over the past few months talk about this) showing that over the past 10 years, the FAA's budget was drastically cut, forcing them to effectively outsource certification in part to Boeing to "self-certify".
diminoten(1)
The problem is that the 737-MAX behaves so differently from the base 737 that it shouldn’t be regulated as the same plane. Definitely a regulatory gap that can and should be addressed. Boeing built an unsafe plane and definitely exploited the issue, but the whole point of regulations is to stop a company like Boeing from shipping an unsafe plane.
Weren't they just as unsafe before the FAA grounded them? The FAA are the agency that originally certified them to fly.
The FAA was actually one of the last regulators in the world to ground the 737-MAX [1].
[1]: https://en.wikipedia.org/wiki/Boeing_737_MAX_groundings#Regu...
The FAA was actually one of the last regulators in the world to ground the 737-MAX [1].
[1]: https://en.wikipedia.org/wiki/Boeing_737_MAX_groundings#Regu...
It's what happens when customer desires override engineering sense, it's worse when bean counters are in the loop, but the problem still exists without them present.
So what you're saying it's the sales guys that overrode the engineers. That sounds even worse.
Also very reminiscent of the F-35 program.
Designing a small collection of different aircraft, each specialised to a particular role, can produce a complementary fleet with capabilities a modern air force needs. But doing so comes with the overhead of producing lots of different aircraft.
Instead, "the spreadsheet" shows that designing one aircraft capable of lots of things comes with the lowest overheads -- but with all the disadvantages of an overcomplicated aircraft and only average performance in each trait.
Designing a small collection of different aircraft, each specialised to a particular role, can produce a complementary fleet with capabilities a modern air force needs. But doing so comes with the overhead of producing lots of different aircraft.
Instead, "the spreadsheet" shows that designing one aircraft capable of lots of things comes with the lowest overheads -- but with all the disadvantages of an overcomplicated aircraft and only average performance in each trait.
Would you also say that about the 787, 747-8, EA-18G Growler, T-7 Red Hawk, MQ-25 Stingray, and GPS Block IIF? All of those were developed in the time after the MD merger.
I agree Boeing isn't the engineering company it used to be, in many ways, but I don't think it's as simple as "controlled by bean-counters".
I agree Boeing isn't the engineering company it used to be, in many ways, but I don't think it's as simple as "controlled by bean-counters".
They aren't having much luck with the USAF tanker contract. The USAF has been rejecting deliveries because of poor manufacturing quality.
Boeing has irrevocably gone down the tubes. It is time to separate the space/defense groups from commercial and reboot them all.
As a Seattle native, it feels strange to seek out A320s when flying, but Boeing has clearly shown that engineering is just a cost center to them.
Boeing has irrevocably gone down the tubes. It is time to separate the space/defense groups from commercial and reboot them all.
As a Seattle native, it feels strange to seek out A320s when flying, but Boeing has clearly shown that engineering is just a cost center to them.
Bean counters keep me from spending all the money.
Instead of building an NMA with a limited market, Boeing needs to build a 737 replacement.
Smith is spot on with his analysis of why no number of mods and modules will make the 737 into a 757.
Here on HN I have ranted about the wobbly bobbly handling, obsolete hydraulics, and noisy crappy cockpit of the 73, versus the modern and comfortable 75.
Pay attention to what the article says about takeoff and landing performance. We used to load the 75 heavily for trips between NY La Guardia and Chicago Midway, or Midway to Washington National. We could NOT load a 737-NG heavily due to field length or climb limits. Boeing made a bad, bad decision to push the 737 instead of advancing a fresh design.
Just wait and watch. They won't abandon the 737 until one or two more are lost due to runway overruns or something else related to its shortcomings. That is WITH better than average pilots, all the sooner to happen with typical ab initio crews.
Here on HN I have ranted about the wobbly bobbly handling, obsolete hydraulics, and noisy crappy cockpit of the 73, versus the modern and comfortable 75.
Pay attention to what the article says about takeoff and landing performance. We used to load the 75 heavily for trips between NY La Guardia and Chicago Midway, or Midway to Washington National. We could NOT load a 737-NG heavily due to field length or climb limits. Boeing made a bad, bad decision to push the 737 instead of advancing a fresh design.
Just wait and watch. They won't abandon the 737 until one or two more are lost due to runway overruns or something else related to its shortcomings. That is WITH better than average pilots, all the sooner to happen with typical ab initio crews.
I also like the intellectual idea of taking an older airframe (767-200) that is suitable for the task and modernizing it once, rather than applying yet another level of patches to something already pushed far outside of it's intended design envelope.
But why is it so hard to develop a new plane now, compared to patching an old one? One would think computers could make a single engineer hugely more effective nowadays than back then. Constraints, generative design, accurate simulations. Additive manufacturing, CNC machines and composites can make manufacturing a lot simpler too. Has it actually reduced any cost? Interest rates are really low too.
Is it that new planes being developed have much stricter regulations? If so, that's a problem, the incentives result in the public being less safe.
The A220 ran so much over budget that the whole program was sold to Airbus. Yet it seems like a really good airplane from what I've read. 787 and A350 were also terribly expensive.
Something similar has happened with nuclear plants. They seem to take much longer to do than way back and are so expensive to be barely profitable. A friend commented that one reason is because top talent doesn't see the nuclear industry as a "cool" thing or a viable career anymore.
There is one additional problem in airplanes and nukes. They are seen as prestige projects by governments. This makes it hard to make regular money in the industry as you always have subsidized competition.
Is it that new planes being developed have much stricter regulations? If so, that's a problem, the incentives result in the public being less safe.
The A220 ran so much over budget that the whole program was sold to Airbus. Yet it seems like a really good airplane from what I've read. 787 and A350 were also terribly expensive.
Something similar has happened with nuclear plants. They seem to take much longer to do than way back and are so expensive to be barely profitable. A friend commented that one reason is because top talent doesn't see the nuclear industry as a "cool" thing or a viable career anymore.
There is one additional problem in airplanes and nukes. They are seen as prestige projects by governments. This makes it hard to make regular money in the industry as you always have subsidized competition.
It was always hard to develop a new plane. For all that the author waxes rhapsodic about the 747's 2 year design to test flight, the 747 development process very nearly killed Boeing (it brought Boeing far closer to the brink than the a380 did for Airbus).
That's true! This book, "The Jetmakers" is available online and it talks about these things, but in the 1945 to 1972 time frame. It is a good read.
http://www.generalatomic.com/jetmakers/index.html
http://www.generalatomic.com/jetmakers/index.html
The best and the brightest are busy optimizing click rates for online advertisement.
Regulation at every level, not just FAA. Labor laws come to mind.
johnmorrow(2)