Hi, please excuse the neophyte and hopefully nonpartisan question here, but in my searches of the forum I've not been able to find a Cliffnotes answer to the above question.

In recent threads on this forum, notably the Boeing vs. Bombardier C Series drama (for which I, as a Canadian taxpayer, have a keen interest), a frequent reason for why people aren't liking the 737 anymore is that its design is old and outdated. I'm wondering what exactly makes the design derving of the moniker? I do understand that some elements of the design are the same as the original prototype, but objectively, are not the wing, tail, engine, gear design, cockpit, and other elements decades newer than the original 737s? And are the processes used to assemble these things refined to industry standards instead of 1960s spec? Granted, some of these elements have likewise not been updated in up to decades of years, but would that not still qualify the design to be at least as old as its direct competitors? It seems that the only constant between the original and current 737s is the fusealge width, in which it compares unfavorably with other offerings in the same category. Also that parts of the plane are assembled from heavier materials than they could be made from today, that are integral to the design and which therefore can never be upgraded.

I understand this is a complex question, and there's tons of personal preference mixed into any relevant debate. I flew a factory-new 737 MAX-8 this month, and I found it just fine. Sure, nacelles aside it doesn't look much different to the two generations that preceded it, but it sure looks a world apart from the 200s I flew in the 80s and which I sometimes still see next to the newest models in here in YYC and YEG. It makes sense that there's only so much blood one can get from a stone, but I grew up with my family's Dodge Grand Caravan whose design has changed so little, that I came to visit my folks once and didn't realize they'd replaced it with a decade-newer model with the same colour!

I'm definitely in favor of innovation in aircraft design and am excited to read about BBD's C Series, the E2s, and Airbus' NEO models alongside the 737 MAXs. But all too frequently I hear that the 737 is past its time and can't fathom what makes it (or for that matter, an A320-200) old and outdated. I'm hoping some more learned people can help explain why this is, and why it should be a factor for today's narrowbody market.

Mark

I am really curious to see the responses you get.

The 737 still has steel cables for flight control inputs instead of fly by wire, although it has some fly by wire features like the spoilers.

It also has a master caution system instead of EICAS.

When it comes to actual performance, avionics, navigation, engines, wing, gear, interior, etc, the design is thoroughly modernized.

This forum usually appreciates cutting edge designs, however airlines often prefer rstablished reluable designs. Partially due to age and years of refinement, the 737 is the most reliable plane that Boeing makes. It is hard to find anything more reliable. Also the bean counters love how cheap the spares are, especially with after market and PMA part options

I am not an engineer, or an expert on the subject, but I am an active cabin crew member with over 14 years of experience on several series of the 737 (from the classics, to the NG and the Max series), as well as experience in working on other Boeing aircraft (717) and Airbus (A320). I can honestly say that, IMHO, the 737 is, by far, the most uncomfortable aircraft. Narrow aisle, small galleys, cabin temperature is not controlled by us, cabin crew, but in the cockpit. Very few ammenities available to make our work easier (i.e. very little counter space).

Just my 2 cents.

Newbiepilot wrote:

I am really curious to see the responses you get.

The 737 still has steel cables for flight control inputs instead of fly by wire, although it has some fly by wire features like the spoilers.

It also has a master caution system instead of EICAS.

When it comes to actual performance, avionics, navigation, engines, wing, gear, interior, etc, the design is thoroughly modernized.

This place

Master caution is a crew alerter on an EICAS system..

The 737 is a lighter airplane with a better (high aspect laminar flow) wing. Contrary to popular a.net opinions of the unknowing, it's an extremely light and capable aircraft up to 3000 miles (where 95% of the nb routes exist).

MrHMSH wrote:

The only thing that's *really* outdated about it is the landing gear, in my opinion. Everything else has been changed, but the gear hasn't and it has put limits on the plane that hamper its capability and competitiveness, at least for the longest 2 variants.

Newbiepilot wrote:

I am really curious to see the responses you get.

The 737 still has steel cables for flight control inputs instead of fly by wire, although it has some fly by wire features like the spoilers.

It also has a master caution system instead of EICAS.

When it comes to actual performance, avionics, navigation, engines, wing, gear, interior, etc, the design is thoroughly modernized.

That's interesting, I think the complete opposite for the gear. Even allowing for the MAX 10, everything else is up to date, but I genuinely don't see how you can consider the gear to be modernised. What's changed for it?

The steel cables controlling gear input are gone on the MAX. Main gear was raised on the NG and nose gear on the MAX

The only thing that's *really* outdated about it is the landing gear, in my opinion. Everything else has been changed, but the gear hasn't and it has put limits on the plane that hamper its capability and competitiveness, at least for the longest 2 variants.

Newbiepilot wrote:

I am really curious to see the responses you get.

The 737 still has steel cables for flight control inputs instead of fly by wire, although it has some fly by wire features like the spoilers.

It also has a master caution system instead of EICAS.

When it comes to actual performance, avionics, navigation, engines, wing, gear, interior, etc, the design is thoroughly modernized.

That's interesting, I think the complete opposite for the gear. Even allowing for the MAX 10, everything else is up to date, but I genuinely don't see how you can consider the gear to be modernised. What's changed for it?

MrHMSH wrote:

Newbiepilot wrote:

The steel cables controlling gear input are gone on the MAX

But the gear itself is unchanged except for the MAX 10. I think that qualifies as a very minor change, especially when you consider the changes elsewhere. If the gear had been updated properly then they wouldn't have the clearance problems for the engines or the rotation angle problems on the longest variants.

Main gear was raised on the NG and Nose Gear raised on the MAX.

Newbiepilot wrote:

The steel cables controlling gear input are gone on the MAX

But the gear itself is unchanged except for the MAX 10. I think that qualifies as a very minor change, especially when you consider the changes elsewhere. If the gear had been updated properly then they wouldn't have the clearance problems for the engines or the rotation angle problems on the longest variants.

Newbiepilot wrote:

MrHMSH wrote:

Newbiepilot wrote:

The steel cables controlling gear input are gone on the MAX

But the gear itself is unchanged except for the MAX 10. I think that qualifies as a very minor change, especially when you consider the changes elsewhere. If the gear had been updated properly then they wouldn't have the clearance problems for the engines or the rotation angle problems on the longest variants.

Main gear was raised on the NG and Nose Gear raised on the MAX.

Fair enough, I'd forgotten the MAX nose gear raise, but never knew the NG got one. I think the overall point still stands though, the gear hamstrings the 737 to this day.

Legacy exit doors would be another 737 hold-out.

What makes the B737 an "old, outdated" design?

It's fuselage. It's been around since the 707, shortened and extended again with the 727 & 737. However, I'm only half serious about the old and outdated fuselage.

So amidst all of these high tech answers, from a purely shallow and aesthetic point of view, the 737 to me looks fat and bulky and less modern.

Personally from looks alone I tend to prefer aircraft with shapely curves... (hence 747 > A380, and A320 family/C Series > 737).

I'm not an engineer, but it's a pretty capable jet as we all know.

However, a lot of opinions seem to agree that a lot more could be achieved by a clean sheet design. You can see a similar sort of effect with the 747-8. Although the 747-8 is smaller, some airlines went for a cleansheet design i.e the A380. I remember a BA pilot saying on twitter once BA chose the A380 as the 747-8 didn't incorporate enough technological advancements over the A380, so make of that what you will.

IMHO, the 737 was revolutionary at it's time it came out, and is a more than capable aircraft since it's design HAS lasted this long. However, with the introduction of the latest MAX versions, that is about as far as the design can go. Any other drastic changes would require a completely new design/fuselage.

Obviously not a lot of pilots on this thread. The most antiquated part of the 737-XXX is.....


The overhead panel. Its a 1960's epic fail.


Ask a pilots which is better to fly... the bus or the 73... most that have flown both leans towards the bus for the room, the overhead panel, and greater automation. Plus, track up on the MFD is really strange IMO.

Embajador3 wrote:

I am not an engineer, or an expert on the subject, but I am an active cabin crew member with over 14 years of experience on several series of the 737 (from the classics, to the NG and the Max series), as well as experience in working on other Boeing aircraft (717) and Airbus (A320). I can honestly say that, IMHO, the 737 is, by far, the most uncomfortable aircraft. Narrow aisle, small galleys, cabin temperature is not controlled by us, cabin crew, but in the cockpit. Very few ammenities available to make our work easier (i.e. very little counter space).

Just my 2 cents.

If I’m not mistaken, the airline chooses the galley size and is not standard across the 737’s. WN had their FA’s redesign a new galley for the -800s and MAX’s.

Agreed, the overhead is probably the biggest relic. Wrt track up, I think that's a customer option.

EICAS - it is my hope that Boeing transitions to this in later MAX models. We are already seeing EICAS-esque alerts showing up on the MFD's. As the NG's progressed, there were a number of improvements that came along in later deliveries. I could certainly see the 'six pack' annunciator moving to MFD.

If we ever get to the day that Boeing makes a wider 737 replacement, and I'm not talking MOM here but a narrow body, would said fuselage, being maybe a foot wider, still be able to travel from Kansas to Washington via rail? Any rail experts on here that might have an idea?

barney captain wrote:

Agreed, the overhead is probably the biggest relic. Wrt track up, I think that's a customer option.

EICAS - it is my hope that Boeing transitions to this in later MAX models. We are already seeing EICAS-esque alerts showing up on the MFD's. As the NG's progressed, there were a number of improvements that came along in later deliveries. I could certainly see the 'six pack' annunciator moving to MFD.

I know you've flown the 73 for a while. The nice thing about the bus is the "interactive" ECAM. When a fault appears and an ECAM checklist comes up on the MFD and disappears as you start moving through the list... thats really incredible and such a step up.

barney captain wrote:

Agreed, the overhead is probably the biggest relic. Wrt track up, I think that's a customer option.

All Boeing aircraft that I’ve operated (744/8, 75, 76, 77) have track up, so I think it’s standard.

Still, it could be my operator’s option.

From a pilot aspect the ancient nose and cockpit windows that were borrow from early design B707. The cockpit wind noise is defining.

The doors are of a very old design of a generation older than even on the oldest 747-100. A few years ago I was shown different aircraft doors and their mechanisms, and it was clear to see that the 737 is a "vintage" airplane.

impromark wrote:

Hi, please excuse the neophyte and hopefully nonpartisan question here, but in my searches of the forum I've not been able to find a Cliffnotes answer to the above question.

In recent threads on this forum, notably the Boeing vs. Bombardier C Series drama (for which I, as a Canadian taxpayer, have a keen interest), a frequent reason for why people aren't liking the 737 anymore is that its design is old and outdated. I'm wondering what exactly makes the design derving of the moniker? I do understand that some elements of the design are the same as the original prototype, but objectively, are not the wing, tail, engine, gear design, cockpit, and other elements decades newer than the original 737s? And are the processes used to assemble these things refined to industry standards instead of 1960s spec? Granted, some of these elements have likewise not been updated in up to decades of years, but would that not still qualify the design to be at least as old as its direct competitors? It seems that the only constant between the original and current 737s is the fusealge width, in which it compares unfavorably with other offerings in the same category. Also that parts of the plane are assembled from heavier materials than they could be made from today, that are integral to the design and which therefore can never be upgraded.

I understand this is a complex question, and there's tons of personal preference mixed into any relevant debate. I flew a factory-new 737 MAX-8 this month, and I found it just fine. Sure, nacelles aside it doesn't look much different to the two generations that preceded it, but it sure looks a world apart from the 200s I flew in the 80s and which I sometimes still see next to the newest models in here in YYC and YEG. It makes sense that there's only so much blood one can get from a stone, but I grew up with my family's Dodge Grand Caravan whose design has changed so little, that I came to visit my folks once and didn't realize they'd replaced it with a decade-newer model with the same colour!

I'm definitely in favor of innovation in aircraft design and am excited to read about BBD's C Series, the E2s, and Airbus' NEO models alongside the 737 MAXs. But all too frequently I hear that the 737 is past its time and can't fathom what makes it (or for that matter, an A320-200) old and outdated. I'm hoping some more learned people can help explain why this is, and why it should be a factor for today's narrowbody market.

Mark

The landing gear was designed for those small engines they originally had the 737max is basically as big an engine they can use. Heck the 737-900 engines are so low to the ground that the case is shaped oblong for ground clearance. It had an amazing run. But it’s rung out. The 321 is showing that.

N757ST wrote:

Obviously not a lot of pilots on this thread. The most antiquated part of the 737-XXX is.....


The overhead panel. Its a 1960's epic fail.


Ask a pilots which is better to fly... the bus or the 73... most that have flown both leans towards the bus for the room, the overhead panel, and greater automation. Plus, track up on the MFD is really strange IMO.

All Boeing models offer Track-Up or Heading up as a catalog option. If you don’t like it, that was what your airline selected. Both are equally available no cost options.

The majority of customers choose Track-Up.

Actually in many ways research has shown Track-Up to be better. Also it’s becoming more necessary in newer models because ADS-B-Out outputs traffic Track angle, not Heading. So ADS-B traffic will be in Track orientation on those models that display ADS-B traffic.

barney captain wrote:

Agreed, the overhead is probably the biggest relic. Wrt track up, I think that's a customer option.

EICAS - it is my hope that Boeing transitions to this in later MAX models. We are already seeing EICAS-esque alerts showing up on the MFD's. As the NG's progressed, there were a number of improvements that came along in later deliveries. I could certainly see the 'six pack' annunciator moving to MFD.

They can’t change to EICAS on the 737. It would affect the type rating and definitely training commitments made to the customers. No way could you have the same type rating on a model in which some have EICAS and some don’t.

BoeingGuy wrote:

N757ST wrote:

Obviously not a lot of pilots on this thread. The most antiquated part of the 737-XXX is.....


The overhead panel. Its a 1960's epic fail.


Ask a pilots which is better to fly... the bus or the 73... most that have flown both leans towards the bus for the room, the overhead panel, and greater automation. Plus, track up on the MFD is really strange IMO.

All Boeing models offer Track-Up or Heading up as a catalog option. If you don’t like it, that was what your airline selected. Both are equally available no cost options.

The majority of customers choose Track-Up.

Actually in many ways research has shown Track-Up to be better. Also it’s becoming more necessary in newer models because ADS-B-Out outputs traffic Track angle, not Heading. So ADS-B traffic will be in Track orientation on those models that display ADS-B traffic.

That’s cool. Maybe it’s me, but HDG up just gives better situational awareness. Just my opinion.

1. Too low - hurts stretches and engine efficiency.
2. Too narrow - hurts passenger comfort and boarding times. And yes, it's noticeable.
3. Too loud. Both in the cockpit, which is a cacophony compared to its competition, and in the cabin. The cockpit horns dragging through the air causes the air to still be tumbling at the tail - hence the
strakes by the vertical stab. And I don't believe the other explanations for those, it's the gawd awful cockpit angles.
4. Too much liability. Kind of unbelievable that a passenger jet was just certified without envelope protection in this age.

It's embarrassing that Boeing thinks this is what the world aviation market wants. I know people will cite the big backlog, but most of those are because Airbus can't stamp out 100 A320's a month - yet.

The 737: One of the best things to happen to commercial aviation in the 20th century, and the absolute worst thing in the 21st.

Others may have said it, but in my opinion, the Boeing 737 is too low to the ground. Originally, its mission was as a city hopper plane. No one ever imagined then that more than 3000 nautical miles would be demanded from a narrow body aircraft. What the low 737 design does is limit the size of the engines. On this, the A321neo is going to eat the 737 MAX 10’s lunch, as this is the sixth stretch from the original design. A clean sheet higher off the ground is needed.

MrHMSH wrote:

Newbiepilot wrote:

MrHMSH wrote:

But the gear itself is unchanged except for the MAX 10. I think that qualifies as a very minor change, especially when you consider the changes elsewhere. If the gear had been updated properly then they wouldn't have the clearance problems for the engines or the rotation angle problems on the longest variants.

Main gear was raised on the NG and Nose Gear raised on the MAX.

Fair enough, I'd forgotten the MAX nose gear raise, but never knew the NG got one. I think the overall point still stands though, the gear hamstrings the 737 to this day.

I do wonder how much the airplane is actually hamstrung by the gear. I have seen Airbus marketing charts emphasizing bigger fans are better and also the better short field performance of the A321 vs 737-900ER. I am sure they win some sales because of it. What I wonder about is how much the compromise actually matters. While Airbus marketing teams can go out and tell everyone that they have the biggest fan, Boeing has some weight advantages from the smaller gear. The 737 has lighter manual cargo doors instead of the heavier powered outward opening doors on the A321, the 737 doesn’t need overwing evacuation slides, the 737 has a lighter gear due to being shorter and using less steel, the fan weighs a little less. The 737 also has a less complicated and lighter flap system than the A321. It is all about compromise with the 737 sacrificing runway performance to keep OEW down. This helps the plane on shorter missions. So in the end, how much is it hamstrung and how much is it optimized differently than the A321? I don’t know the answer. I wouldn’t call the gear situation outdated. Boeing could raise the gear, add slides, add powered cargo doors, put on a bigger fan, etc if they wanted, but it may not be optimized for the mission that they were trying to do.

The narrower fusilage also prohibits containers, unlike the Bus. Loose baggage for a loco or a cityhopper isn’t really a problem, but with the ranges of the the LR and MAX, being able to stick a few pallets of cargo in the hold of the LR will really appeal to the legacies with premium cabins up front using them on TATL flights for example.

Look at it this way though, developing a clean sheet replacement will cost several billion. It’s still selling in the thousands, yes the NEO will likely outsell it but would all that investment claw back enough market share to justify the expense? And a clean sheet design wouldn’t have the common type rating the locos love so much.

Embajador3 wrote:

I am not an engineer, or an expert on the subject, but I am an active cabin crew member with over 14 years of experience on several series of the 737 (from the classics, to the NG and the Max series), as well as experience in working on other Boeing aircraft (717) and Airbus (A320). I can honestly say that, IMHO, the 737 is, by far, the most uncomfortable aircraft. Narrow aisle, small galleys, cabin temperature is not controlled by us, cabin crew, but in the cockpit. Very few ammenities available to make our work easier (i.e. very little counter space).

Just my 2 cents.

Yes! Poxy little aircraft to work in, they just make the damn thing longer and longer. I'm glad I don't have to face those galleys ever again.

The door arming procedure on the 737 still means crawling on the floor and attaching the slide with the Girt Bar to the aircraft ! A 707 design and a joke that they still use it on the MAX

Mutt wrote:

1. Too low - hurts stretches and engine efficiency.
2. Too narrow - hurts passenger comfort and boarding times. And yes, it's noticeable.
3. Too loud. Both in the cockpit, which is a cacophony compared to its competition, and in the cabin. The cockpit horns dragging through the air causes the air to still be tumbling at the tail - hence the
strakes by the vertical stab. And I don't believe the other explanations for those, it's the gawd awful cockpit angles.
4. Too much liability. Kind of unbelievable that a passenger jet was just certified without envelope protection in this age.

It's embarrassing that Boeing thinks this is what the world aviation market wants. I know people will cite the big backlog, but most of those are because Airbus can't stamp out 100 A320's a month - yet.

The 737: One of the best things to happen to commercial aviation in the 20th century, and the absolute worst thing in the 21st.

That exactly !! I can just add, as others have said, the antic overhead panel, and that master caution with 6 packs system. The probability of having the 12 lights lighten during a recall check don't exceed 20%, even on fairly new aircrafts. I know that system has been certified 60 years ago, but what a disgrace to still have to rely on it...
Oh, I almost forgot about the air conditioning ! Specially since the new "eFlow" system. Try to get a homogeneous cabin temperature on the ground when outside temp is below 10°C and forward door open... Good luck !!

HTCone wrote:

The narrower fusilage also prohibits containers, unlike the Bus. Loose baggage for a loco or a cityhopper isn’t really a problem, but with the ranges of the the LR and MAX, being able to stick a few pallets of cargo in the hold of the LR will really appeal to the legacies with premium cabins up front using them on TATL flights for example.

Look at it this way though, developing a clean sheet replacement will cost several billion. It’s still selling in the thousands, yes the NEO will likely outsell it but would all that investment claw back enough market share to justify the expense? And a clean sheet design wouldn’t have the common type rating the locos love so much.

It is the inward opening cargo doors that prohibit containers, not the fuselage width. A soft sided or shorter container would work but waste space. If Boeing added powered outward opening cargo doors, they probably could fit containers. The compromise is that the door systems are heavy combined with the added weight and volume reduction associated with containers that airlines may not want the option.

A clean sheet design will have lower reliability for years. It takes a long time to perfect a design to address all the potential reliability problems associated with new designs. The production system on the 737 is also optimized for low costs. Airlines also appreciate all the spare parts inventory on the aftermarket making parts cheaper. New designs result in higher part costs in most cases.

na wrote:

The doors are of a very old design of a generation older than even on the oldest 747-100. A few years ago I was shown different aircraft doors and their mechanisms, and it was clear to see that the 737 is a "vintage" airplane.

Why can't 757 doors be used? They have the same cabin cross section dimensions.

N757ST wrote:

Ask a pilots which is better to fly... the bus or the 73... most that have flown both leans towards the bus for the room, the overhead panel, and greater automation. Plus, track up on the MFD is really strange IMO.

I heard one pilot describe it as “ball crushing.”

Seems to me if Boeing redesigned the cockpit for the 757, they could have redesigned the cockpit for the 737 at some point. And if in fact it is ball crushing, it seems the airlines would have pressured Boeing to make changes.

Mutt wrote:

4. Too much liability. Kind of unbelievable that a passenger jet was just certified without envelope protection in this age..

I find that your comment lacks knowledge of how the 737 flight controls work and the certification basis for the roll yaw and pitch axis controls. The 737 has a combination of yaw dampers, feel and centering units, a Mach trim actuator, elevator feel shift computer.

http://www.737ng.co.uk/B_NG-Flight_Controls.pdf

The 737 flight controls are safe and not too much of a liability. Please don’t let a lack of education about how the system works scare you. Envelope protection isn’t enough to prevent an airplane from stalling for example. It takes a trained pilot following established procedures to ensure a safe flight.

This advisory circular may be worth reading if you think the 737 Flight Control system is a liability

https://www.faa.gov/documentLibrary/med ... _672-1.pdf

questions wrote:

N757ST wrote:

Ask a pilots which is better to fly... the bus or the 73... most that have flown both leans towards the bus for the room, the overhead panel, and greater automation. Plus, track up on the MFD is really strange IMO.

I heard one pilot describe it as “ball crushing.”

Seems to me if Boeing redesigned the cockpit for the 757, they could have redesigned the cockpit for the 737 at some point. And if in fact it is ball crushing, it seems the airlines would have pressured Boeing to make changes.

Boeing wanted to put the the 757 nose on the 737NG, because it is more aerodynamic, but WN wanted commonality of spares with the classic 737's. I'm pretty sure that WN used its influence to make the cockpit as similar to the classic 737's as possible to enable it to have one pilot pool.

Big difference bet the 737 and 320 is the cabin width for passengers. The curvature is really noticeable in the 737 the 320 is more comfortable a plane to fly in too.

And that’s comparing the Jetstar 320 to qantas 737 where the seats in Jetstar are like sitting on a plank of wood

Newbiepilot wrote:

HTCone wrote:

The narrower fusilage also prohibits containers, unlike the Bus. Loose baggage for a loco or a cityhopper isn’t really a problem, but with the ranges of the the LR and MAX, being able to stick a few pallets of cargo in the hold of the LR will really appeal to the legacies with premium cabins up front using them on TATL flights for example.

Look at it this way though, developing a clean sheet replacement will cost several billion. It’s still selling in the thousands, yes the NEO will likely outsell it but would all that investment claw back enough market share to justify the expense? And a clean sheet design wouldn’t have the common type rating the locos love so much.

It is the inward opening cargo doors that prohibit containers, not the fuselage width.

Thanks for the correction.

Qf648 wrote:

Big difference bet the 737 and 320 is the cabin width for passengers. The curvature is really noticeable in the 737 the 320 is more comfortable a plane to fly in too.

And that’s comparing the Jetstar 320 to qantas 737 where the seats in Jetstar are like sitting on a plank of wood

For me that’s overrated. I’ve flown the 737 a lot more because I often fly AS. However, I don’t feel some huge difference in comfort when I fly an A320. I don’t notice any difference at all. It’s more dependent on seat pitch.

To me the 737 feel like a more solidly built aircraft but I’m well aware of some of the older system design like the spinning trim wheel and overhead panel.

cschleic wrote:

As was pointed out, the 737 has the same fuselage design as the 707. So when the last MAXs are still flying 40 years from now, it'll be using a fuselage design that's more than 100 years old. Reliable? Yes. But missing out on potential updates? Definitely.

I don’t believe that is true. The damage tolerant designs have changed the way structural components are designed and inspected. Fuselage skin thickness has changed. Widespread fatigue damage has led to design changes. Here is an example

Lap joint corrosion occurring in service was first reported in 1970. Boeing Service Bulletin 737-53-1017 was released later that year to seal the lap joints to prevent corrosion, but this was only partially effective (sealing was also done in production starting at line number 249).

The cold bond lap joint design was discontinued in production in 1972. A redesigned lap joint that had increased joint thickness, allowing the rivets to transfer the pressurization loads, was introduced at line number 292. The adhesive bond that was used for load transfer was eliminated.

http://lessonslearned.faa.gov/ll_main.c ... LLTypeID=2

All the "outdated" talk is plain Bunk!! the B737 is glying to Hawaii from the west coast and Alaska and ws ETOPS certified before ANY Airbus.
for reliability?? the B737 is at the top of the heap! The A320,A319 AND A321 will have a damn LONG way to go to Equal the B737's reliability Record or standard. Yeah the B737 design is "long in the tooth" But! it's set a standard the Airbus might not EVER match

Quoting Newbiepilot:

""I find that your comment lacks knowledge of how the 737 flight controls work and the certification basis for the roll yaw and pitch axis controls. The 737 has a combination of yaw dampers, feel and centering units, a Mach trim actuator, elevator feel shift computer.

http://www.737ng.co.uk/B_NG-Flight_Controls.pdf

The 737 flight controls are safe and not too much of a liability. Please don’t let a lack of education about how the system works scare you. Envelope protection isn’t enough to prevent an airplane from stalling for example. It takes a trained pilot following established procedures to ensure a safe flight.

This advisory circular may be worth reading if you think the 737 Flight Control system is a liability""

If your username is accurate, I can probably say that I have almost as many hours at the 737's controls as you've been alive

Mutt wrote:

4. Too much liability. Kind of unbelievable that a passenger jet was just certified without envelope protection in this age.

It's embarrassing that Boeing thinks this is what the world aviation market wants. I know people will cite the big backlog, but most of those are because Airbus can't stamp out 100 A320's a month - yet.

Points 1 through 3 make perfect sense, but I'm not sure what you're suggesting in point 4. The only inference I can draw is that you're saying the 737 (including its modern iterations) is "less safe". When looking at the NG, disregarding the classics, there is a lower fatal crash rate compared to the A320 family according to http://www.airsafe.com/events/models/rate_mod.htm.

Your editorial about what Boeing think is misplaced, and I wonder to whom this is causing any embarrassment. It seems that notwithstanding the "outdated" qualities of the airframe, it is a safe and reliable machine that generates a substantial amount of profit for both its manufacturer and its operators.

Mutt wrote:

Quoting Newbiepilot:

""I find that your comment lacks knowledge of how the 737 flight controls work and the certification basis for the roll yaw and pitch axis controls. The 737 has a combination of yaw dampers, feel and centering units, a Mach trim actuator, elevator feel shift computer.

http://www.737ng.co.uk/B_NG-Flight_Controls.pdf

The 737 flight controls are safe and not too much of a liability. Please don’t let a lack of education about how the system works scare you. Envelope protection isn’t enough to prevent an airplane from stalling for example. It takes a trained pilot following established procedures to ensure a safe flight.

This advisory circular may be worth reading if you think the 737 Flight Control system is a liability""

If your username is accurate, I can probably say that I have almost as many hours at the 737's controls as you've been alive

I concur with Newbie. If you really are a 737 pilot, your comment shows a high level of unprofessionalism and lack of knowledge. You simple DO NOT call the airplane you supposedly fly a safety liability. That is very uncool and disgraceful.

If you have concerns about the safety of the 737 then take it up with the FAA.

That’s also technically incorrect. While we all agree that parts of the 737 Max are not the most futuristic, it’s a proven and safe design. Plus, there are a lot of updates to the 737 Max flight control system that I’m sure you would have no clue about. The only thing it’s a liability for is an unskilled pilot.

I sat in a 737 cockpit a while ago. My first thought was, "this is very agricultural". There's "stuff" everywhere. The ergonomics were acceptable in the 60s, but they seem like a disaster by current standards.

Having said that, the 737 makes good money for the airlines and is a reliable, safe aircraft. And that's the important thing.

Boeing is quite capable is building a modern cockpit. The reason the 737 cockpit is so antiquated is purely down to certification grandfathering.

Compare the overhead panel on the 737NG with the 320.

Mutt wrote:

Quoting Newbiepilot:

""I find that your comment lacks knowledge of how the 737 flight controls work and the certification basis for the roll yaw and pitch axis controls. The 737 has a combination of yaw dampers, feel and centering units, a Mach trim actuator, elevator feel shift computer.

http://www.737ng.co.uk/B_NG-Flight_Controls.pdf

The 737 flight controls are safe and not too much of a liability. Please don’t let a lack of education about how the system works scare you. Envelope protection isn’t enough to prevent an airplane from stalling for example. It takes a trained pilot following established procedures to ensure a safe flight.

This advisory circular may be worth reading if you think the 737 Flight Control system is a liability""

If your username is accurate, I can probably say that I have almost as many hours at the 737's controls as you've been alive

Envelope protection is quite capable of preventing a stall. That's one of the primary functions of Airbus envelope protection. However, an aircraft without envelope protection is not unsafe.

Newbiepilot wrote:

I do wonder how much the airplane is actually hamstrung by the gear. I have seen Airbus marketing charts emphasizing bigger fans are better and also the better short field performance of the A321 vs 737-900ER. I am sure they win some sales because of it. What I wonder about is how much the compromise actually matters. While Airbus marketing teams can go out and tell everyone that they have the biggest fan, Boeing has some weight advantages from the smaller gear. The 737 has lighter manual cargo doors instead of the heavier powered outward opening doors on the A321, the 737 doesn’t need overwing evacuation slides, the 737 has a lighter gear due to being shorter and using less steel, the fan weighs a little less. The 737 also has a less complicated and lighter flap system than the A321. It is all about compromise with the 737 sacrificing runway performance to keep OEW down. This helps the plane on shorter missions. So in the end, how much is it hamstrung and how much is it optimized differently than the A321? I don’t know the answer. I wouldn’t call the gear situation outdated. Boeing could raise the gear, add slides, add powered cargo doors, put on a bigger fan, etc if they wanted, but it may not be optimized for the mission that they were trying to do.

How much it matters: for the 738 and MAX 8, probably not a lot. for the 739, MAX 9 and MAX 10, probably quite a lot more. Despite the lighter weight, the 737 barely has an advantage on efficiency, probably less than 2% with the MAX and NEO, but is less flexible, and with the larger variants especialy less capable.

Airbus marketing teams may be onto something: the A321 didn't win 'a few' sales against the -900ER, it won most, and it was even worse for the MAX 9. If the efficiency is a wash (which it basically is), then it must be the capability and flexibility that has driven sales, because otherwise I don't see an explanation for why the gap should be so large. The majority of flights are still within ranges where the 737 should be more or else equal for efficiency, and yet the larger variants don't sell well. If the larger fan wasn't more efficient, then I suspect Airbus would have chosen a narrower engine, there's literally no reason for them not to choose the more efficient option.

Boeing could make those changes, but it would require a lot of weight penalty to get the gear, slides, cargo doors, it's quite possible that it would make the 737's efficiency advantage disappear, on top of the cost of development, loss of commonality and more time to develop. If it were possible and advantageous it would have been done, but it hasn't.

Overall how much has the shorter gear hamstrung the 737? It's cost lost of market share in the A321 space, allowed Airbus to get away with a large premium on the A321 for many years and has hurt sales where airlines are looking for more than one size of aircraft. The MAX 9 and MAX 10 sales have been good enough overall, and unless you can present a compelling reason why that's because of something other than lower performance/felexibility then I think I'm mostly right.

Starlionblue wrote:

I sat in a 737 cockpit a while ago. My first thought was, "this is very agricultural". There's "stuff" everywhere. The ergonomics were acceptable in the 60s, but they seem like a disaster by current standards.

Having said that, the 737 makes good money for the airlines and is a reliable, safe aircraft. And that's the important thing.

Boeing is quite capable is building a modern cockpit. The reason the 737 cockpit is so antiquated is purely down to certification grandfathering.

Compare the overhead panel on the 737NG with the 320.

Mutt wrote:

Quoting Newbiepilot:

""I find that your comment lacks knowledge of how the 737 flight controls work and the certification basis for the roll yaw and pitch axis controls. The 737 has a combination of yaw dampers, feel and centering units, a Mach trim actuator, elevator feel shift computer.

http://www.737ng.co.uk/B_NG-Flight_Controls.pdf

The 737 flight controls are safe and not too much of a liability. Please don’t let a lack of education about how the system works scare you. Envelope protection isn’t enough to prevent an airplane from stalling for example. It takes a trained pilot following established procedures to ensure a safe flight.

This advisory circular may be worth reading if you think the 737 Flight Control system is a liability""

If your username is accurate, I can probably say that I have almost as many hours at the 737's controls as you've been alive

Envelope protection is quite capable of preventing a stall. That's one of the primary functions of Airbus envelope protection. However, an aircraft without envelope protection is not unsafe.

The 737 does have Elevator Feel Shift. That will greatly increase column forces when you are holding it aft and approaching stall. While it’s not directly an envelope protection it will give tactile feel of an impending stall and, in effect, fight you back. It’s pretty noticeable when it fires and does strongly promote stall prevention, so to speak.

The 737 Max and some 737 NGs also have RCAS. That gives you a red arrow on the PFD and a voice aural, “ROLL RIGHT” or “ROLL LEFT” when the airplane reaches 45 degrees of bank. This gives clear visual and aural guidance to recover in the event of a roll upset condition. (The KC-46 has this too. The 777 and 787 don’t need it due to having Bank Angle Protection.)

Agreed, not advanced technology but very safe.