Let's keep this discussion, civil, shall we ?

Quoting Matt6461 (Reply 48): operating economics of the plane, of which CASM gives a pretty good picture,

You are just picking up on one of the fallacies of A.net : CASM, as it is, relates to a whole airline fleet, cabin configurations for all types...etc... and only then refer to -at the said airline- cost structure and financial procedures.
CASM has never been meant for comparing airplanes ( what level of comfort, what network...etc...)

Secondly

Quoting Matt6461 (Reply 48): Greater-than-prevailing sweep is not optimal except for a gate-constrained aircraft. The 747 has more sweep than A380, for example, but not because it's an optimal design.

...and of course, Boeing engineers and aerodynamicists are just a bunch of ignorant nincompoops, un able to build a,n optimum wing for the 748I ?.. almost as bad as the Airbus crowd who cannot see how pretty the 380 would look with a scimitar wing ? Is that it ?

Sorry . Nothing can prevent you from using both supercritical, high aspect ratio airfoils and sweep angle. Don't be impressed with fashion designing.
What really bugs me is that you want to talk about new wing without going through the aerofynamics of an aircraft design.
Your excel spreadsheet is so basic and so simplistic and only geared toward your demonstration, which then fails.

Quoting Matt6461 (Reply 48): You focus on approach speed category but ignore wake separation, which certainly contravenes your "least disturbance possible" dictum.

That could be a very interesting discussion...I have news for you : the A380 has a wake that is not worse than a 747.
Politics and a certain measure of safety concerns still impose these separations... which should - and will - be lifted, especially when the FAA starts playing fair (but I'm not holding my breath ). The book written by Claude Lelaie on the A380 flight tests is quite interesting...

Quoting Matt6461 (Reply 48): Does "same performance" mean "same approach speed?" I mean who cares in the end?

Operators do as it is also an indication of runway performance, both at takeoff and at landing... and let's not forget : climb performance, too.

Quoting Matt6461 (Reply 48): he tailplane is huge though and disproportionate in size to passengers carried.

As we're supposed to discuss technicalities, jugements of vaues have no place here.
I do suggest you also have a look at a parameter this forum never talks about : the transport coefficient. It could give you another look at perceived (in-)efficeiencies of a given airplane.
The Breguet equation is a great tool, mostly over-used on this forum. We should accept our times and the progress it has brought.

[Edited 2015-08-02 14:09:59]

Quoting Pihero (Reply 50): You are just picking up on one of the fallacies of A.net : CASM, as it is, relates to a whole airline fleet, cabin configurations for all types...etc... and only then refer to -at the said airline- cost structure and financial procedures. CASM has never been meant for comparing airplanes ( what level of comfort, what network...etc...)

CASM must also be taken in terms of RASM.

An F seat has a very high CASM compared to a Y seat. An F seat also commands 6-10 times the fare.

An A380 filled with Y seats in the tightest configuration possible will have the lowest CASM of any airliner in production. However, no airline operates such a configuration.

If CASM would be so important every airline would fly their planes cramped with as many Y seats as possible, the truth is they do not. CASM is something that does influence the decision of an airline when looking at suitable planes for a route, for which they know the demand and their desired cabin layout. It is not suitable to compare the performance of airplanes in general.

Regarding the lack of room for a winglet:

The leading edge slats leave very little outboard clearance against the 80 m box, but there is more room to work with on the trailing edge outboard of the ailerons. Would this particular situation not be ideally suited for a spiroid winglet?


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Photo © Rui Alves - Madeira Spotters

Quoting WingedMigrator (Reply 53): Would this particular situation not be ideally suited for a spiroid winglet?

OT, but: They really got a patent on that? Prior art much?

Quoting Matt6461 (Reply 42): BUT - if the fuse's lift produces, say, 10x the induced drag of the wing per unit of lift, it seems better to add a few extra tons of wing than to chase fuse lift. Even 10% more wing seems better, rather than 10x induced drag. Again, this is assuming a "tube-wing" plane, not a different design.

Aerodynamic laymen here, but..... fuselage drag is induced drag, hence it is energy being lost in the form of vortexes created. That is bad, if you have the fuselage all by itself. But there are also the wings, and that is where the same vortexes can increase the energy of the airflow above that wing, making the wing more efficient. Since the fuselage is their anyways, it may very well be that some more fuselage lift creates an overall more efficient fuselage/wing combination and that the weight saved vs. a wing to match that efficiency just more than just makes up for the relatively inefficient way said lift came into being. After all the fuselage tuned to optimum lift is free structure, you have one anyways, while anything you do to the wing to make it more efficient is bound to make the wing heavier. And you pointed out numerous times how extra weight generates more extra weight.

best regards
Thomas

Quoting seahawk (Reply 52): If CASM would be so important every airline would fly their planes cramped with as many Y seats as possible, the truth is they do not. CASM is something that does influence the decision of an airline when looking at suitable planes for a route, for which they know the demand and their desired cabin layout. It is not suitable to compare the performance of airplanes in general.

What matters is a combination of things.

Cost per available sq. ft.-mile, CASM, and RASM. We all know that the A321-NEO is more efficient than the 727. But if you go by CASM or cabin square area, you get different results.

Quoting tommy1808 (Reply 54): fuselage drag is induced drag

If you're talking about fuselage lift, then yes. But fuselage lift is small so fuselage lift-induced drag is small. Most fuselage drag is parasitic drag.

Quoting tommy1808 (Reply 54): Quoting WingedMigrator (Reply 53): Would this particular situation not be ideally suited for a spiroid winglet? OT, but: They really got a patent on that? Prior art much?

The patent for spiroid winglets that Aviation Partners has is from around 1990. That is about 25 years ago and in 2020 it will be 30 years. So IMO any patent should out of the way.

Spiroid winglets according to Aviation partners bring about 11% compared to the wing without a winglet. It would be according to those numbers the most effective wingtip device designed up to now.

Quoting mjoelnir (Reply 56): Spiroid winglets according to Aviation partners bring about 11% compared to the wing without a winglet. It would be according to those numbers the most effective wingtip device designed up to now.

I believe spiroid winglets bring up issues with both crosswind handling and flutter, though. They never have caught on.

Quoting mjoelnir (Reply 56): The patent for spiroid winglets that Aviation Partners has is from around 1990.

That's why.. i've seen that as a "young scientists" competition entry in the mid-80s..I would need to dig through a lot of old "Flug Revue" to find it though.

Quoting mjoelnir (Reply 56): If you're talking about fuselage lift, then yes. B

uops, yeah. I just mean fuselage lift. What just my amateur idea how those vortexes may be beneficial for the wing performance.

Best regards
Thomas

Quoting Pihero (Reply 50): You are just picking up on one of the fallacies of A.net : CASM, as it is, relates to a whole airline fleet, cabin configurations for all types

Depends. You think of CASM as a measure to compare the costs of various aircraft within the fleet of a particular airline.

But when used to compare aircrafts it is usually done by applying a standard or average cabin configuration. If that is done and done properly, CASM becomes very effective and useful to compare aircraft. That way CASM becomes one of the most important parameters.

So CASM can be used very well to compare aircraft if comparable configurations or average seat densities are assumed.

And guess what?

This is exactly what everybody does for aicrcraft vs aircraft comparison. Comparing seat cost under the assumption of comparable configurations is done by: Boeing, Airbus, the press, Anet, airlines when they go shopping...

Are they all wrong? I don´t say this is the only important parameter but it certainly is a very important one. Probably the most important one.

Quoting DocLightning (Reply 55): Cost per available sq. ft.-mile, CASM

If the CASM is calculated based on average or standard configurations these two correlate proportionally...

And to be fair, this is what Matt did all the time.

Quoting rheinwaldner (Reply 59): If the CASM is calculated based on average or standard configurations these two correlate proportionally...

Actually, they rarely do. Because every aircraft has a different cabin shape (width, length, sidewall shape, etc.), "average or standard" configurations vary greatly between aircraft and hardly ever utilise the available space with equal seating densities (seats per unit floor area).

Quoting rheinwaldner (Reply 59): airlines when they go shopping...

When airlines go shopping, they look at the various options with many possible seating configurations that adhere to their own specific seating standards. They most certainly do not make comparisons based on any notional "average or standard" seating layout.

Airlines do not make purchase decisions based on CASM. Many people here claim that CASM is king but, having been involved in very many aircraft acquisition projects, I have never seen CASM used as a decision making metric. When making comparisons, airlines are more interested in comparing specific route performance for different aircraft in different configurations.

There is no point having the lowest seat-mile costs if you can't fill the seats, or don't have enough seats. The CASM proponents would probably be very surprised at how often an aircraft and/or configuration with significantly higher seat-mile costs can actually generate more profit for an airline on a route.

Quoting rheinwaldner (Reply 59): Quoting DocLightning (Reply 55): Cost per available sq. ft.-mile, CASM If the CASM is calculated based on average or standard configurations these two correlate proportionally...

CASM, as I understand it in an airline is the *cost per available seat-mile*.
I agree that the airline efficiency is a comparison between CASM and RASM - *Revenue per available seat-mile*

Quoting speedbored (Reply 60): having been involved in very many aircraft acquisition projects, I have never seen CASM used as a decision making metric.

  

Thanks. That puts things in a better perspective.

BTW, see how Boeing has changed the rules on airliners' comparison with their new IAC (Integrated Aircraft Configuration Ruleset ), and realize that comparing docs from each OEM was futile and erroneous. ( Mind you, I do not think they completely solved the problem).

Quoting DocLightning (Reply 55): Cost per available sq. ft.-mile, CASM, and RASM. We all know that the A321-NEO is more efficient than the 727. But if you go by CASM or cabin square area, you get different results.

Sure, because CASM only makes sense if you know the seat layout you want, so that metric only makes sense for each airline.

Quoting Pihero (Reply 61): CASM, as I understand it in an airline is the *cost per available seat-mile*. I agree that the airline efficiency is a comparison between CASM and RASM - *Revenue per available seat-mile*

My understanding is that rules that force (forced?) US airlines to publish RASM and CASM date back to the era of airline regulation, and their popularity is that it's one of the few metrics that is generally available.

Quoting Pihero (Reply 61): Quoting speedbored (Reply 60): having been involved in very many aircraft acquisition projects, I have never seen CASM used as a decision making metric. Thanks. That puts things in a better perspective.

I think that perspective has been well understood for a long time. The issue as I understand it is that there is no other metrics available for general use. The ones that matter are the ones that each airline uses to describe its requirements and these are never generally available. That raises the question "is it better to have no acceptable metrics and thus no basis for comparison and thus no discussion, OR to have POOR metrics that serve as a basis for comparison and discussion"?

To me the answer is the later, but of course others disagree, usually others who have access to better metrics.

I face the same problem in my work. It'd be great if there were a set of metrics that could perfectly model what our product does, but life just isn't that simple.

Quoting Pihero (Reply 61): BTW, see how Boeing has changed the rules on airliners' comparison with their new IAC (Integrated Aircraft Configuration Ruleset ), and realize that comparing docs from each OEM was futile and erroneous. ( Mind you, I do not think they completely solved the problem).

Nor will it ever be solved, because it's in each vendor's interest to have rules that favor their own offerings, so no truly consistent rules will be put into use.

Quoting Revelation (Reply 63): That raises the question "is it better to have no acceptable metrics and thus no basis for comparison and thus no discussion, OR to have POOR metrics that serve as a basis for comparison and discussion"?

Except these poor metrics are being used as if they were the primary, if not only, basis for comparison.

Quoting speedbored (Reply 60): Actually, they rarely do. Because every aircraft has a different cabin shape (width, length, sidewall shape, etc.), "average or standard" configurations vary greatly between aircraft and hardly ever utilise the available space with equal seating densities (seats per unit floor area).

So CASM is at least better for comparison than cost per floor space? Because it respects all these things (if you put the same configuration in two different aircraft)?

Quoting speedbored (Reply 60): When airlines go shopping, they look at the various options with many possible seating configurations that adhere to their own specific seating standards.

In other words, they compare the CASM that would be the outcome using their configuration. But they compare the CASM. And that was my point.

Quoting speedbored (Reply 60): They most certainly do not make comparisons based on any notional "average or standard" seating layout.

Agreed, the average seating layout allows to compare aircraft on a market-level. That´s meant if Boeing or Airbus are talking about cost per seat.

Quoting Revelation (Reply 63): To me the answer is the later

And I would agree, as long as those metrics are being used in the right way with a proper understanding of their limitations.

Quoting Stitch (Reply 64): Except these poor metrics are being used as if they were the primary, if not only, basis for comparison.

  
And then there is the problem of there not being any standard for exactly how CASM should be calculated when it is used in those comparisons.

Most people seem to understand that seating configuration will affect CASM. How many even consider the multitude of other real-world factors that can affect CASM in real operations? Things like stage length, cargo, or even baggage allowances, to name just a few. There are just too many variables that can be tweaked to favour one side or the other when making seat-mile (or floor-area-mile) comparisons, which is why it is not a metric that airlines use to compare aircraft.

That is not to say that airlines are not aware of, or do not use, their seat-mile costs. They are useful for things like year-on-year comparisons, or to judge the effectiveness of cost-cutting measures, for example.

Quoting rheinwaldner (Reply 65): So CASM is at least better for comparison than cost per floor space?

Well, imo, it depends on what you are doing the comparison for. For the a.net "my aircraft is better than your aircraft" type comparisons, I would argue that area-mile costs are probably better because it removes any suggestion of cheating on the config to favour one side or the other.

Quoting rheinwaldner (Reply 65): In other words, they compare the CASM that would be the outcome using their configuration. But they compare the CASM.

As I said in my previous post, in my experience, airlines do not compare CASM at all when making decisions on aircraft type, because costs are only one part of the picture. Also, per-seat comparisons ignore the impact that varying numbers of seats can have on route performance.

Airlines don't just want the lowest cost per seat option, they want whatever will make them the most money. So, for each option, they are more interested in acquisition costs, trip costs, numbers of seats in each cabin class, estimated revenues, and availability.

An aircraft with higher notional seat-mile costs can often be a better (i.e. more profitable) choice when you factor in other things such as capacity/demand, competition, availability, commonality, engine types, etc. etc. etc.

Quoting Pihero (Reply 50): Let's keep this discussion, civil, shall we ?

Quoting Pihero (Reply 50): Your excel spreadsheet is so basic and so simplistic and only geared toward your demonstration, which then fails.

Yes, let's.

Quoting Pihero (Reply 50): and of course, Boeing engineers and aerodynamicists are just a bunch of ignorant nincompoops, un able to build a,n optimum wing for the 748I ?

Not at all my point. The 748 wing has suboptimally high sweep because it's a reloft on the bones of a '70's wing. With the 748, Boeing tried exactly what A380NEO enthusiasts recommend here: it put new engines and a stretch on a bad wing.

Quoting Pihero (Reply 50): the A380 has a wake that is not worse than a 747. Politics and a certain measure of safety concerns still impose these separations

This sounds like a conspiracy theory. Have any evidence that A380 has no larger wake vortices than a 747?

Quoting speedbored (Reply 60): Airlines do not make purchase decisions based on CASM.

Here's a real-world example of exactly the type of purchase decision that you claim does not exist:

Quote: Rainey cites a higher trip cost for the A380 compared to smaller widebodies like the 787 despite comparable per seat costs as the main challenge to adding the type to United’s fleet.

http://www.flightglobal.com/news/art...es-not-work-for-united-cfo-413079/

Quoting Pihero (Reply 50): CASM, as it is, relates to a whole airline fleet, cabin configurations for all types...etc... and only then refer to -at the said airline- cost structure and financial procedures. CASM has never been meant for comparing airplanes ( what level of comfort, what network...etc...)

Quoting seahawk (Reply 52): If CASM would be so important every airline would fly their planes cramped with as many Y seats as possible, the truth is they do not.

Quoting speedbored (Reply 60): There is no point having the lowest seat-mile costs if you can't fill the seats, or don't have enough seats.

I am grouping these responses together to address a point that some here frequently make. The commentators claim to debunk an "A.net myth" that CASM is really really really important; seems to me they propound a new myth in which basic economics doesn't apply to airlines. That's my basic response, I'll provide further details below.

As a metapoint, I'll remark that often commentators who claim to "debunk" a "myth" are granted deference for appeals to some deeper knowledge. This is a dangerous trend. No matter the level of specialized knowledge claimed by a poster, their assertions must be verified for whether they make sense. As I'll argue below, the group claim advanced in the quotes above doesn't pass this test.

Quoting speedbored (Reply 66): And then there is the problem of there not being any standard for exactly how CASM should be calculated when it is used in those comparisons.

This is indeed a problem but it is largely surmountable. With enough time and effort, one can create a LOPA for the respective cabins based on standardized rules. One can use cabin area as a proxy, which is a good metric and even better if one adjusts for airplane-specific characteristics.

Leeham does LOPA's for all of its comparative analyses. The airwaysinsight article linked in the OP did as well. One can check the acceptability of these LOPA's against floor areas, for minimum seat width assumptions, etc.

What one should not do is claim that airplane interiors contain spaces whose dimensions and possibilities can only be reckoned in extremely specific and idiosyncratic cases, rendering moot all normal cognition of space and experience. It's not THAT difficult.

Quoting speedbored (Reply 66): I would argue that area-mile costs are probably better because it removes any suggestion of cheating on the config to favour one side or the other.

OK! I'll mostly agree! But now we pretty much have a CASM comparison.

Quoting speedbored (Reply 66): As I said in my previous post, in my experience, airlines do not compare CASM at all when making decisions on aircraft type, because costs are only one part of the picture.

First, see above-linked story about A380 and 787. UA doesn't want the A380 because its unit costs (whether CASM or cost per average cabin M2/ft2) are "similar" to the 787 at much greater capacity.

Second, it simply doesn't follow that "do not compare CASM at all" because costs are "only part" of the picture. Range, cabin comfort, capacity, cargo/freight, jet/piston-engined, real/toy, plane/plain are also "only part" of the picture but are extremely important.

Quoting speedbored (Reply 66): So, for each option, they are more interested in acquisition costs, trip costs, numbers of seats in each cabin class, estimated revenues, and availability.

-Acquisition cost is part of CASM. Unit costs that exclude acquisition are Cash Operating Costs - COC.
-Trip cost is CASM*seats
-"estimated revenues" is just RASM*seats

You haven't come close to disproving the extremely high relevance of CASM/RASM here. Each of your factors besides availability is directly related to CASM/RASM. Of course nobody disputes that the CASM of an airplane that you can't have for 6 years is irrelevant if you need that plane now.
---------------------------------------------------------------

Does everyone know the fable/essay/meme of the hedgehog and the fox? http://en.wikipedia.org/wiki/The_Hedgehog_and_the_Fox

The fox knows many things; the hedgehog one big thing. Each style of thought is important to ordinary life and intellectual history.

I am operating as a hedgehog here - I have one big idea: that the A380 isn't efficient enough for its size; that its inefficiency is traceable to a suboptimal wing; and that it probably could be superb if rewinged.

I'm a hedgehog in the midst of foxes, mostly. I admit to lacking specialized knowledge, I'm happy to admit when I'm wrong on a particular like wing twist. I'm appreciative of all this foxy knowledge here, even when it's presented in a context critical of me.

But so far I remain convinced that my big idea is the best of the ideas presented in this forum regarding the A380's future.

Nobody has disputed, so far, that a longer, lighter wing would dramatically improve fuel efficiency. As far as I can tell it's indisputable. The only question is - by how much?

But to have a meaningful discussion of that question, we first have to ask - what is a meaningful target of fuel efficiency delta? What level of fuel burn would create an A380NEO/NWO/PIP capable of providing ROI sufficient to justify the project?

-10%?

-15%?

-20%?

-25%?

-30%?

-35%?

-40%?

Regardless how you evaluate my aerodynamic model, the fuel burn figure, once plugged into the DOC cost, creates a CASM delta whose fundamentals are based on the best publicly available data on A380 operating costs (Leeham's).

A 17% per-pax fuel burn delta creates a ~7% CASM delta for a NEO with ~16% price premium over CEO. That's just arithmetic, not aerodynamics. Doesn't matter how you get that 17% aerodynamically or mechanically. Is that good enough to make the A380NEO sell well? I doubt it, especially if you need a stretch to get to 17%.

For those who accept the worldview that CASM/RASM and basic economics actually matter to airlines, does anyone want to venture a guess as to what level of CASM delta would materially affect A380 sales prospects?

The only think one can get from what United says is that they seem to think that people would not pay more for a 3-4-3 A380 than for a seat on a 3-3-3 787. CASM without a similar level of passenger comfort is just a pointless number.

Quoting Matt6461 (Reply 67): The 748 wing has suboptimally high sweep because it's a reloft on the bones of a '70's wing. With the 748, Boeing tried exactly what A380NEO enthusiasts recommend here: it put new engines and a stretch on a bad wing.

This is where one gets too much in lovce with one's pet theory and starts leaving objectivity :
See the article of Kingxley-Jones on the 748i :
"Aside from the stretch, there is little visual difference between the -8 fuselage and earlier marks. But the same is not true for the wing.

"The wing is key to this airplane, combined with the GEnx engines, and what makes it so dramatically different from its predecessors," says Dickinson. "There's the advanced technology airfoil with the supercritical wing and raked wingtip designed using computational fluid dynamics, giving it the same technology level as the 787 wing. It is extremely efficient."

The wing shares little with the 747-400 other than its 35˚ sweep and incorporates new materials that help reduce weight. The design features an optimised reloft and retwist, while the raked tip (in place of the winglet on the -400) increases wing span by 4m to 68.4m. "The new wing has similar dimensions to the earlier wing, but it is quite different. We really did not use any of the earlier aerodynamic features," says Dickinson

So : Span increase by 4 meters - which is your favourite theory.
Use of modern supercritical airfoils
Raked wingtips ( a good solution on a high-aspect ratio wing )

... and it's still suboptimal ?
So why bother with the A380, then ?

(Excerpt from Flight In-Focus 748 Technical Description

Quoting Matt6461 (Reply 67): Have any evidence that A380 has no larger wake vortices than a 747?

The better question is "Have you any evidence that the A380 has a larger wake than the 748 ?"... and yes I have that evidence, from the test director himself.

Quoting Matt6461 (Reply 67): Here's a real-world example of exactly the type of purchase decision that you claim does not exist:

That's comical : so, both aircraft ( the 787 and the A380 have the same CASML, but United will never buy the A380 ? Doesn't that tell you that there are, obviously, other reasons for making a fleet decision ? ( hint : hub )

Quoting Matt6461 (Reply 67): -Acquisition cost is part of CASM.

To be perfectly accurate, it is the way the airline computes its fleet age ==> amortization that counts, not the buying price.

Quoting Matt6461 (Reply 67): Trip cost is CASM*seats -"estimated revenues" is just RASM*seats

In all my airline life, I've never seen that sort of backward computation : one starts with the operating revenue ( as the airline considers it ), then goesq to the operating costs ( still as the airline computes them ) and eventually compares both to the offered - or available - seat x miles...hence your so-called RASM and CASM which are in fact labeled as *unit costs or revenues*..
Doing revenues = RASM x seats is just trying to bite one's own tail.. you go nowhere, but round and round.

Quoting Matt6461 (Reply 67): Here's a real-world example of exactly the type of purchase decision that you claim does not exist:

Actually, that real-world example proves my point. The mere fact that he mentions that the A380 has higher trip costs proves that he is not making his decision based on CASM alone.

Quoting Matt6461 (Reply 67): seems to me they propound a new myth in which basic economics doesn't apply to airlines.

No, you are. Basic economics says that the airlines will choose whatever option makes them the most money, not which one has the lowest notional seat-mile costs figure.

Quoting Matt6461 (Reply 67): No matter the level of specialized knowledge claimed by a poster, their assertions must be verified for whether they make sense.

And what exactly in my assertion that airlines decide based on what makes them the most money does not make sense? CASM is not, and never will be, a measure of how profitable an aircraft will be on a route - too many other factors come into play. Why do you persist in dismissing all of the real-world factors that make a huge difference? Real airlines exist to make money in the real world, not to win some academic contest.

Quoting Matt6461 (Reply 67): With enough time and effort, one can create a LOPA for the respective cabins based on standardized rules. One can use cabin area as a proxy, which is a good metric and even better if one adjusts for airplane-specific characteristics.

Maybe, but you are still left with a metric that is of no use whatsoever to an airline when they are deciding which aircraft will be more profitable for them. No matter how much time and effort you spend on defining your metric it will still only ever be useful to compare which aircraft gets a better result from that metric. It will still not bear any relation to how much money a real airline might make from each different aircraft/configuration, in the real world, on a real route.

Quoting Matt6461 (Reply 67): What one should not do is claim that airplane interiors contain spaces whose dimensions and possibilities can only be reckoned in extremely specific and idiosyncratic cases, rendering moot all normal cognition of space and experience.

Why not? That is exactly what happens in the real world - airlines and manufacturers spend vast amounts of time and money trying to work out how to make use of every inch of space. Airlines have their own standards for their seats and if they can't fit a whole seat in the available space, they don't just cut one in half and stick it in anyway.

Quoting Matt6461 (Reply 67): Trip cost is CASM*seats

No it is not.

Quoting Matt6461 (Reply 67): -"estimated revenues" is just RASM*seats

No it is not.

Quoting Matt6461 (Reply 67): You haven't come close to disproving the extremely high relevance of CASM/RASM here.

Maybe not. But I speak from many years of experience involved in very many aircraft acquisition projects with many different airlines and finance companies, and every major manufacturer. Not once, ever, have I seen CASM, or any measure related to CASM, used as a metric in that decision making process.

You, on the other hand, have also not proved it has any relevance, let alone "extremely high relevance", and have no experience whatsoever to back up your assertion that it has. Just because you keep repeating it does not make it true.

Quoting Matt6461 (Reply 67): Each of your factors besides availability is directly related to CASM/RASM.

No, they are not. And almost every one of the factors I have mentioned will affect profitability by different factors for each aircraft type or configuration being considered. Many of them will also alter CASM differently for different aircraft types/configurations/engines (stage length, for example).

Or do you seriously believe that airlines make their aircraft purchase decisions with no reference at all to the real-world routes that they plan to be using them on?

Quoting Matt6461 (Reply 67): But so far I remain convinced that my big idea is the best of the ideas presented in this forum regarding the A380's future.

Tell us something we don't know. Unfortunately, very many people with real-world experience disagree.

CASM has many very valid uses. Comparing different aircraft is not, however, one of them. Except, of course, for the purposes of a pissing contest.

Quoting speedbored (Reply 60): Airlines do not make purchase decisions based on CASM. Many people here claim that CASM is king but, having been involved in very many aircraft acquisition projects, I have never seen CASM used as a decision making metric. When making comparisons, airlines are more interested in comparing specific route performance for different aircraft in different configurations.

On the other hand, I've been involved in many airline campaigns where fuel burn guarantees are written for specific routes with airline defined seat configurations. The same guarantees were made for the OEM competing airplane. When combined with other cost guarantees (maintenance costs, crew costs, navigation fees, landing fees, purchase price etc), the resulting airline specific CASM does become an important decision making tool for the airline.

Matt is trying to provide a fair generic comparison CASM between airplanes that mimics the airline decision process to illustrate the differences between airplane models. I always appreciate data as opposed to hand-waving. While the data may not be totally accurate due to the assumptions that need to be made, it does illustrate interesting trends.

Quoting Pihero (Reply 50): Quoting Matt6461 (Reply 48):You focus on approach speed category but ignore wake separation, which certainly contravenes your "least disturbance possible" dictum. That could be a very interesting discussion...I have news for you : the A380 has a wake that is not worse than a 747. Politics and a certain measure of safety concerns still impose these separations... which should - and will - be lifted, especially when the FAA starts playing fair (but I'm not holding my breath ). The book written by Claude Lelaie on the A380 flight tests is quite interesting...

The ICAO sanctioned A380 Wake Vortex Steering Team consisted of representatives from FAA, JAA(EASA), Eurocontrol and Airbus. Suggesting that the A380 separation standards are due to the FAA alone implies that EASA and Eurocontol played a subservient role in the decision making process. I've never seen EASA kowtow to the FAA on any subject if the data indicated a different conclusion was in order. I suspect EASA agrees with the A380 separation distances.

Quoting Pihero (Reply 69): See the article of Kingxley-Jones on the 748i :

Quoting Pihero (Reply 69): ... and it's still suboptimal ? So why bother with the A380, then ?

As I said, the 748's wing is a reloft on "old bones." I agree that a ton of new - and very expensive - features went into the 748 version of the wing. But these don't change the fact that 748 shares with the A380 a fatal flaw: low aspect ratio.

The 748 also has fairly high wing- and span-loading, making its performance even more suboptimal than A380's wing.

But don't take my word for it, follow the money: as poorly as the A380 sells, the 748i is even worse.

Why bother with the A380? This question was debated extensively around last century's turn, and the results appear to vindicate Boeing (and if only they'd had the courage of conviction not to compete at all with the 748, they'd have saved $5bn).

*to be clear I don't think the A380's poor sales vindicate Boeing's position in the VLA debate - they mostly reflect the quality of today's VLA offerings.

Quoting Pihero (Reply 69): The better question is "Have you any evidence that the A380 has a larger wake than the 748 ?"... and yes I have that evidence, from the test director himself.

OldAeroGuy gives a good answer here.

I'll just add that it should be your burden to produce, not just allude to, some evidence of the anti-A380 conspiracy. It's not my burden to disprove a conspiracy.

Quoting speedbored (Reply 70): Actually, that real-world example proves my point. The mere fact that he mentions that the A380 has higher trip costs proves that he is not making his decision based on CASM alone.

But I'm not arguing you look at CASM alone. In fact, I've argued that the cost efficiency versus capacity tradeoff is key. I've said this repeatedly and you know it well, have even posted a thread in TechOps about it, to which you responded: MBEY: Why A380 Doesn't Sell (and NEO Won't Either) (by Matt6461 May 29 2015 in Tech Ops) I have repeatedly stated that the A380 is the most efficient aircraft flying, but not efficient enough for its size.

In comparing two aircraft of different sizes, it is highly relevant (1) how much bigger X is than Y and (2) how much more efficient is X than Y.

Only you have argued that CASM doesn't matter "at all."

This is one thing that makes it difficult to engage with you Speedbored - you're ungenerous. I don't mean that in the sense that my feelings are hurt. I mean that, because you consistently assume only the worst/dumbest imaginable version of your opponents' arguments, your opponents have to frequently remind you of what they are actually saying. In oral argument before a judge, this would be sanctionable as wasting the tribunal's time - I think it should be in this forum as well.

Quoting speedbored (Reply 70): You, on the other hand, have also not proved it has any relevance, let alone "extremely high relevance", and have no experience whatsoever to back up your assertion that it has. Just because you keep repeating it does not make it true.

This is another unfortunate rhetorical device of yours - the appeal to authority. You like to remind people of your experience - one might suspect that sometimes that is your main motive for posting. We're all judged by the quality of our arguments here, not by unverifiable biographical claims.

A problem arises where two people who have claims to experience disagree on an issue presented - as here between you and at least a couple others who have made claims to experience and whose reputations countenance some deference. How are forumers to differentiate their claims and yours?

Just the quality of your arguments. So put your best forward and stick to them. Nobody of serious mind is going to simply accept statements based on claimed authority in an anonymous internet forum.

Quoting OldAeroGuy (Reply 71): the resulting airline specific CASM does become an important decision making tool for the airline.

I would still argue that the derived CASM is merely an output from the decision making process, not an input to it. The airline will still make their decision based on total costs and total revenues. As you say yourself, "specific routes with airline defined seat configurations" completely removes the need for cost to be per seat or per mile as the numbers of seats and number of miles is fixed.

Otherwise, if the airline were to make their decision based on per-seat numbers then they could be giving up a lot of potential profit if the aircraft with the best per-seat numbers had fewer seats. What they care about is the likely total profit to be generated by each aircraft.

Just as an example, let's say that aircraft X has CASM/RASM figures that generate a profit of $1 per SM and has 180 seats, and aircraft Y has CASM/RASM figures that generate a profit of $0.95 per SM but has 200 seats. Making the decision based purely on the CASM/RASM figures would result in the airline making $10 less for every mile flown.

Quoting Matt6461 (Reply 72): But don't take my word for it, follow the money: as poorly as the A380 sells, the 748i is even worse.

So the aircraft with the new wing is selling "even worse"? Good point.

Quoting Matt6461 (Reply 72): This is one thing that makes it difficult to engage with you Speedbored - you're ungenerous.

Yes, you keep throwing this one at me. And I suppose that you also consider yourself not to be "ungenerous" in your incessant dismissal of everyone else who attempts to disagree with you. Or perhaps you do not consider yourself "ungenerous" in the way that you simply ignore any question which you cannot answer without demonstrating the weakness in your argument, for example:

Quoting speedbored (Reply 70): And what exactly in my assertion that airlines decide based on what makes them the most money does not make sense?

Quoting Matt6461 (Reply 72): Only you have argued that CASM doesn't matter "at all."

No. Many others have as well, but you simply dismiss everyone who does because you require it as the core of your argument.

Quoting Matt6461 (Reply 72): because you consistently assume only the worst/dumbest imaginable version of your opponents' arguments, your opponents have to frequently remind you of what they are actually saying.

No, unlike you, I assume nothing. I just read the version that is written. If you want me to accept a different version then that is what you should write.

Quoting Matt6461 (Reply 72): You like to remind people of your experience

Only when it adds context to something I am claiming. But you seem to dismiss any post by anyone with obvious experience (and I do not mean me) if it does not agree with something you have gleaned from a book, or Leehamnews. Your problem is that, having read something somewhere, you think that you fully understand every aspect of it. Real-world understanding cannot be gained from a book - it requires experience.

But, even without experience, just a small amount of research and some plain old-fashioned common sense would tell you that CASM cannot be used to make meaningful comparisons between aircraft because, even with the same airline and the same aircraft, CASM will vary significantly from one route to another. Or with the same aircraft on the same route, CASM will vary from one airline to another, or even just because of different engine selections.

Meaningful comparisons can only be made when using data derived from real-world airline configurations and real-world routes to generate real-world cost, revenue, and profit figures. And then, CASM is irrelevant because the numbers of seats and numbers of miles are known.

Quoting Matt6461 (Reply 72): In fact, I've argued that the cost efficiency versus capacity tradeoff is key.

And, as many people have pointed out to you, this is not the case. You are so hung up on cost cost cost that you simply cannot see the commercial reality, that there will always be circumstances in which the less "efficient" option can generate the highest profits, even after taking account of capacity. Also, higher capacity does not, as you seem to believe, always mean a negative impact on yields.

Quoting Matt6461 (Reply 72): In oral argument before a judge, this would be sanctionable as wasting the tribunal's time

Yes, you keep drawing the legal parallels. This is a discussion forum, not a court of law, but let's go with it for now - perhaps you could start by showing us the evidence to back up your claim:

Quoting Matt6461 (Reply 67): the extremely high relevance of CASM/RASM here.

Because I would love to understand where all the airlines that I have worked with have been going wrong by never using it in their aircraft acquisition decision making process.

CASM is a result of the decision making process, not a parameter to base the decision on.

Obviously the aircraft matching the airline´s needs best, will often be the one with the lowest CASM but that CASM is not a parameter you can use to compare aircraft types in general.

I would like to come back to the United statement that the 787 has a similar CASM as a A380, this compares a 3-3-3 787 against a 3-4-3 A380. Those configurations represent very different levels of passenger comfort (or discomfort in the case of the 787). And even Businessfirst is very different level of comfort to the business class on a Emirates A380.

So in the end you would need the pure raw data for both the planes, like fuel burn, fuel price, MX costs, capital costs, etc..

Then you put in a cabin layout of similar comfort levels and you end up with a CASM that is comparable. Working with statements made by airlines and manufacturers is pointless.

Quoting speedbored (Reply 66): So, for each option, they are more interested in acquisition costs, trip costs, numbers of seats in each cabin class, estimated revenues, and availability.

- aquisition cost: really? More important than the operating cost?
- trip cost: really? They are more interested in trip cost regardless the seat count? That does not sound credible...
- number of seats: ok, now you list CASM as well.
- estimated revenues: the revenue of comparable configurations will hardly differ a lot (if at all).
- availability: oh, thats something that would favour A380s strongly anyway

Quoting speedbored (Reply 66): An aircraft with higher notional seat-mile costs can often be a better (i.e. more profitable) choice when you factor in other things such as capacity/demand, competition, availability, commonality, engine types, etc. etc. etc.

Sounds like hot air because several of the parameter you mention are reflected in CASM.

Quoting speedbored (Reply 70): The mere fact that he mentions that the A380 has higher trip costs proves that he is not making his decision based on CASM alone.

Now you sound confused. The higher trip cost are obvious and meaningless for any comparison. But he does mention that the lack of a seat cost delta would be his issue.

Quoting speedbored (Reply 73): I would still argue that the derived CASM is merely an output from the decision making process, not an input to it.

Nobody said it is an input. It is one of the primary outputs of the decision making process. Once it is know, a decision can be taken.

Quoting rheinwaldner (Reply 75): Nobody said it is an input. It is one of the primary outputs of the decision making process. Once it is know, a decision can be taken.

True, but the big point was that the thread tries to compare the CASM of different aircraft types in general, which simply is not wrong. CASM is heavily influenced by very airline specific parameters. If you want to compare airplanes in general you would need stripped down metric, like fuel burn + MX costs (and even that is airline specific) per seat or m² floor space for configurations of similar passenger comfort levels.

Quoting rheinwaldner (Reply 75): aquisition cost: really? More important than the operating cost?

I did not say that it is more important.

Quoting rheinwaldner (Reply 75): They are more interested in trip cost regardless the seat count?

Nor did I say that.

Quoting rheinwaldner (Reply 75): number of seats: ok, now you list CASM as well.

No - trip cost and seat count does not equal CASM. Using a standardised definition of CASM, as Matt keeps suggesting, ignores specific route details, which is what makes the huge difference that airlines need to know about in order to make any sort of sensible decision. They need to understand the comparable performance of aircraft on the routes that they intend to fly, not on some notional standard route that nobody flies. The differences between routes are very far from insignificant.

Quoting rheinwaldner (Reply 75): estimated revenues: the revenue of comparable configurations will hardly differ a lot (if at all).

But very few aircraft with real-world airline seat configurations have "comparable configurations". That is a large part of the reason why airlines do not use CASM in making this sort of decision.

Quoting rheinwaldner (Reply 75): Sounds like hot air because several of the parameter you mention are reflected in CASM.

No, when using some generic standardised definition of CASM, they most definitely are not.

Just because a CASM value can be calculated from some of the values that I mention, does not mean that those values can be replaced by some standardised value for CASM, and give the same answer.

Quoting rheinwaldner (Reply 75): Now you sound confused. The higher trip cost are obvious and meaningless for any comparison.

I'm not at all confused. Even if you wish to dismiss the higher trip cost as meaningless because you want to make a comparison based on CASM, you still need to factor in the seat differences and their possible affect on revenues, especially when the size difference is sufficiently large to maybe permit a difference in frequency. You simply can not make any meaningful comparison based on CASM alone.

Quoting rheinwaldner (Reply 75): But he does mention that the lack of a seat cost delta would be his issue.

No he does not. The article clearly states that he "cites a higher trip cost for the A380 compared to smaller widebodies like the 787 ... as the main challenge ..."

If, as some people seem to be claiming, CASM is the primary driver in the decision making process, perhaps they could explain why Rainey is not buying A380s right now, given that they have "comparable per seat costs" to the 787 and far far better availability?

Quoting rheinwaldner (Reply 75): Nobody said it is an input.

Matt certainly did. Many times. He keeps asserting that it is the primary driver in the decision making process:

Quoting Matt6461 (Reply 48): I have very clearly identified the main driving factors of the business case: (1) operating economics of the plane, of which CASM gives a pretty good picture

Quoting rheinwaldner (Reply 75): It is one of the primary outputs of the decision making process. Once it is know, a decision can be taken.

I agree that it can be one of the outputs. But the decision is always made based on projected profits, not on CASM.

Given that, for publicly listed airlines, airline management are legally obliged to only make decisions that they believe will maximise shareholder value, perhaps one of the CASM-is-king proponents could explain to us exactly how they can fulfill that obligation if they make their aircraft purchase decisions based on CASM, and not based on projected profits?

Notwithstanding the respect I have for both Oldaeroguy and Rheinwaldner, I am totally behind Speedbored on this :
His is a real-life experience of what counts for an airline, Oldaeroguy speaks from a vendor's perspective and so is Rheinwaldner.
There are quite a few confusions on this thread :

Quoting rheinwaldner (Reply 75): aquisition cost: really? More important than the operating cost?

Sorry if I wasn't clear enough in a previous post : the acquisition cost is totally embedded in the DOC - direct operating cost - of any type in the fleet. As I said, that particular aspect depends on how trhe airline computes the amortization of that price in the DOC : some airlines consider an in-fleet life at 10, 15 or more years, which could make quite a difference on the importance of that aspect in the DOC., hence the hourly cost of operating that type.

Quoting rheinwaldner (Reply 75): trip cost: really? They are more interested in trip cost regardless the seat count? That does not sound credible...

Here again, Speedbored is right ;
Just take two airplanes, for a route study. Let's imagine that they cost exactly the same on a 5 000 nm trip, on which the airline is counting on 200 passengers all year round.
One aircraft - A - seats 230 pax, the other - B - 250.
You can do the maths : B has a lower CASM... A has the higher RASM, meaning a greater efficiency over that route.
( In real life, B would in fact cost more due to the dead weight of the extra cabin equipment, everything else equal )

Quoting rheinwaldner (Reply 75): number of seats: ok, now you list CASM as well. - estimated revenues: the revenue of comparable configurations will hardly differ a lot (if at all).

See the two paragraphs above.

Quoting rheinwaldner (Reply 75): Sounds like hot air because several of the parameter you mention are reflected in CASM.

Sorry, but it is really the other way around.

Quoting Matt6461 (Reply 72): As I said, the 748's wing is a reloft on "old bones." I agree that a ton of new - and very expensive - features went into the 748 version of the wing. But these don't change the fact that 748 shares with the A380 a fatal flaw: low aspect ratio.

That's what I understand from your post : Boeing engineers are just a bunch of raving mad incompetent nincompoops, according to you. Oh ! Boy ! They don't even understand *aspect ratio* !

Quoting Matt6461 (Reply 72): I'll just add that it should be your burden to produce, not just allude to, some evidence of the anti-A380 conspiracy. It's not my burden to disprove a conspiracy.

Forget the conspiracy. I asked you to provide one source that proves that the A380 has a stronger wake than a 744.
As usual, when challenged, you leave in a tangent... like about the 748 example.
I had thought that here on Tech-Ops, we deal with facts and figures and refrain from the *suboptimal*...etc... judgements of value.

Quoting speedbored (Reply 73): Yes, you keep drawing the legal parallels

A damn sight better than litterary references and sel-serving arguments, methinks.

[Edited 2015-08-10 07:00:43]

Quoting speedbored (Reply 73): So the aircraft with the new wing is selling "even worse"? Good point.

Quoting Pihero (Reply 79): That's what I understand from your post : Boeing engineers are just a bunch of raving mad incompetent nincompoops, according to you. Oh ! Boy ! They don't even understand *aspect ratio* !

This is the last time I'll make this frustratingly obvious point:

The 748 wing is not new.

Quoting Pihero (Reply 79): I asked you to provide one source that proves that the A380 has a stronger wake than a 744.

Good Lord, Pihero. The source is every single aviation regulatory agency.

Quoting speedbored (Reply 73): some plain old-fashioned common sense would tell you that CASM cannot be used to make meaningful comparisons between aircraft

I've somehow neglected to make this point so far...

Your entire argument is flatly disproved by the facts of the real world.

In every comparison of similar aircraft, the one with lower CASM wins. Thus 77W killed off A346, A35J is killing off 77W, A320NEO killed off 737NG, etc.

For comparisons of different size aircraft, the bigger one doesn't sell much unless it's a lot more efficient:
-748, which has higher unit costs than 77W and greater capacity, is basically dead.
-A380 has only marginally lower unit costs than 77W/787, but much greater capacity, and is dying.

I've never understood how you can make your argument, given the actual state of the world, but perhaps I'm beginning to:

-The airline purchasing campaigns you've experienced don't use something named "CASM," BUT
-You seem to agree with OldAeroGuy that they do use guarantees of the individual components of CASM (fuel burn, mx, etc.)

You seem to conclude that, because something named "CASM" isn't used, it is irrelevant. Even when all of CASM's components are contractually specified in an RFP response.

Besides the "naming" error, your basic problems are twofold:
-failure to see that a metric can be descriptive of a decision-making process without being part of it.
-failure to distinguish general levels of description from the particular

Take baseball for example. Much statistical analysis goes into baseball player performance. Analysts could dismiss all this work and insist, simplistically and pedantically, that only runs scored win baseball games. When choosing which baseball players to hire, they could ignore metrics like batting average, OPS, WAR, etc. A good batting average never wins a game, so why care about batting average?

This would mirror your pedantic repetition that only "most profit" matters. In an unhelpful and tautological sense, you and the poor baseball analyst are right of course. Only profit and runs scored matter to the decision of "who wins?" But if you want to predict who will win, you have to use metrics that are not identical to, but rather are descriptive/predictive of, the decisional outcome metric (runs scored or profit). In baseball that's batting average, OPS, etc. Here, CASM gives great insight into which plane will provide the most profit.

Re your specific/general conceptual error: It is true that, in some circumstances, a bigger plane with higher CASM will be the best choice. The 748i did, after all, sell a few dozen frames. A worse baseball team will beat a better one up to 40% of the time. These are specific and minority cases, I'm talking about the overall attractiveness of an airliner or overall prowess of a baseball team. For the general cases - which teams will be good, which airliners will sell - we go to fundamentals like CASM/RASM for airliners and batting average/OPS for baseball teams.

I don't really care what you tell me about your use/nonuse of this metric because the real world facts are on my side, not yours: aircraft with lower CASM sell better; especially widebody aircraft with lower capacity AND lower CASM sell better.

You often accuse me of ignoring the "real world" into which you claim special insight. How you do intend to convince us of your "CASM isn't important" thesis in light of the real world's rejection of it?

[Edited 2015-08-10 16:11:09]

Quoting Matt6461 (Reply 80): This is the last time I'll make this frustratingly obvious point: The 748 wing is not new.

Got to admire your self-confidence, no matter how misguided:
http://www.boeing.com/commercial/747...hts/technologically-advanced/wing/
"New State-of-the-Art Wing"
http://www.flightglobal.com/news/art...al-description-amp-cutaway-378866/
" effectively all-new - but similarly sized - wing".
https://en.wikipedia.org/wiki/Boeing_747-8
"the new wing"
http://www.boeing-747.com/everything.../Boeing-747-8-new-wing-design.html
"new wing design"
http://airwaysnews.com/blog/2015/02/...intercontinental-airline-delivery/
"Boeing claims the new 747 has the world’s most modern ‘wing/engine’ airliner platform, with raked wingtips on an entirely new wing design"

Need I go on?

Quoting Matt6461 (Reply 80): Your entire argument is flatly disproved by the facts of the real world.

Only if you live on another planet. Maybe take the blinkers off and actually read and try to understand what people (and it is not just me) are telling you.

Quoting Matt6461 (Reply 80): In every comparison of similar aircraft, the one with lower CASM wins.

No, it does not, not always. The fact that this is true in the majority of cases is just a happy coincidence, but it is the exceptions that prove you wrong.

Quoting Matt6461 (Reply 80): Thus 77W killed off A346, A35J is killing off 77W, A320NEO killed off 737NG, etc.

Yet again you just go ahead and make bold statements about something, without bothering to check the facts.

Quoting Matt6461 (Reply 80): You seem to conclude that, because something named "CASM" isn't used, it is irrelevant. Even when all of CASM's components are contractually specified in an RFP response.

Just because all of the components that you require to calculate CASM exist in the decision making process that I describe does not mean that you can make the decision based on CASM.

You just do not seem to get the point, that the calculation of CASM specifically removes some of the components that are required in order to make that decision, namely number of seats and number of miles. Once those are removed, CASM simply cannot be used to determine total profit for any option. Or are you suggesting that airlines would make their choice based on profit per seat-mile?

Or maybe you are suggesting that the airlines would calculate profitability for each route by first calculating CASM for each route and then multiplying seat count and miles back in? Why would they bother doing that when they can go directly to total profit from the original numbers without ever stopping at CASM?

The reason why CASM is never used in the decision making process is because it is not a required step in the calculation of likely profitability, which is what any publicly listed airline is legally obliged to base their decision on.

Quoting Matt6461 (Reply 80): It is true that, in some circumstances, a bigger plane with higher CASM will be the best choice.

So you admit that you are wrong then? Or are you just contradicting yourself?

Quoting Matt6461 (Reply 80): I don't really care what you tell me about your use/nonuse of this metric because the real world facts are on my side, not yours: aircraft with lower CASM sell better; especially widebody aircraft with lower capacity AND lower CASM sell better.

I agree (apart from the "real world facts are on my side" part). But, again, that is just a happy coincidence. The aircraft with lower CASM sell better because they are projected to make more money for the airlines that decide to buy them, and for no other reason.

Quoting Matt6461 (Reply 80): You often accuse me of ignoring the "real world" into which you claim special insight. How you do intend to convince us of your "CASM isn't important" thesis

I have never claimed any special insight. There is nothing "special" about my experience, and there are many people here with far more experience than I have. My only claim is to have some specific knowledge that is based on real-world experience, rather than gleaned from books, websites and assumptions. And, just for the record, I have not been theorising; I have been stating facts gained from having been there. I also do not claim that "CASM isn't important" - I have actually stated that it has many perfectly valid, and important, uses. It is just that comparing aircraft for airline suitability is not one of them.

I, and others, have already tried to explain to you why CASM alone cannot be used to make these sorts of decisions. You really need to take off your CASM-is-king blinkers and think a little more about the commercial realities that airlines have to operate under. Then, just maybe, you would understand.

I notice that you completely ignored the two questions I posed in my previous post, probably, I suspect, because the answers would be inconvenient to your agenda. But I would suggest that you ought to try to answer them, even just to yourself - you might learn something.

Also not withstanding the respect I have for you Pihero...but

Quoting Pihero (Reply 79): the acquisition cost is totally embedded in the DOC

I was not sure about that. But then that means that it is also reflected in CASM. So SpeedBored mentioning it as important separate factor was wrong again..

I am not exactly sure why anyone would doubt that CASM is an absolute key metric comparing the efficiency of aircraft operations.

And as the efficiency of aircraft operations is used for many purposes CASM is also used for many purposes. But I am absoltely sure that the expected seat mile cost are one of the ultimate deciding factors when selecting new aircraft.

Matt is right. There is no example of an aircraft that consistently kept up market share if it had a CASM disadvantage > 5% or so against another very similar aircraft. Can´t think of a single one...

There is also no example of an aircraft that continued to sell well as soon as a >20% smaller aircraft appeared with a less than 5% CASM disadvantage.

Quoting Matt6461 (Reply 80): In every comparison of similar aircraft, the one with lower CASM wins.

OK, what is the CASM of the 77W? Simple question. Answer it.

Quoting rheinwaldner (Reply 82): I am not exactly sure why anyone would doubt that CASM is an absolute key metric comparing the efficiency of aircraft operations.

Because CASM is dependent on seat count. An AC 789 has a different CASM from an NH 789. Similarly, the Four Seasons 752 has a different CASM than a DL 752.

We all know that the A321 is more efficient than the 707, but the metric by which we measure that changes and so the degree to which it is more efficient is also variable depending on metric.

CASM is important, but it has some important limitations.

A A321NEO with a full first class cabin would probably have a CASM not much better than a 707 in a fully ecomomy cabin.

CASM is a result made from operating cost divided by seat numbers and both numbers are very specific for each airline. Saying CASM is king today can easily be corrected to "fuel burn is important", because that is what is actually meant in this debate.

Quoting rheinwaldner (Reply 81): I am not exactly sure why anyone would doubt that CASM is an absolute key metric comparing the efficiency of aircraft operations.

I'm not sure that anyone doubts that. I have myself said that CASM has many valid uses and it provides a very useful metric when analysing operations at a fleet level, especially when comparing month-on-month or year-on-year performance to determine trends. But it has limitations that mean it simply cannot be used in fleet acquisition decisions, because it omits important parts of the picture that are required in order to be able to make such a decision.

Quoting rheinwaldner (Reply 81): So SpeedBored mentioning it as important separate factor was wrong again..

How so? Given that I am claiming that CASM is not used in making a purchase decision, how could it be considered without being included as a factor on its own?

Regardless of whether you consider acquisition cost to be included because it is already covered by CASM, or trip cost, acquisition cost is, by itself, an extremely important determining factor in the decision making process, as airlines need to be able to actually fund an acquisition. No point ordering the lowest CASM option if you can't actually raise the funds to pay for it - a basic commercial reality that Skymark recently proved.

It is also worth remembering that different acquisition methods (cash purchase, loan-funded, leasing, etc. etc.) can seriously alter the acquisition cost component of CASM.

Quoting rheinwaldner (Reply 81): And as the efficiency of aircraft operations is used for many purposes CASM is also used for many purposes.

True. I have said as much myself. But aircraft acquisition decisions is not, and can never be, one of them.

Quoting rheinwaldner (Reply 81): There is no example of an aircraft that consistently kept up market share if it had a CASM disadvantage > 5% or so against another very similar aircraft. Can´t think of a single one...

That may be true but the fact that you required the ">5%" qualifier proves my point; that there are circumstances in which a higher CASM aircraft will be the better (i.e. more profitable) option. If what Matt is claiming were true then you would have been able to say:
"There is no example of an aircraft that consistently kept up market share if it had a CASM disadvantage against another very similar aircraft. Can´t think of a single one..."

Quoting DocLightning (Reply 82): Because CASM is dependent on seat count.

   And many other factors. Stage length, for example - an aircraft doing, say, 8x500 mile sectors a day will have a very different CASM from the same aircraft doing 4x1000 mile sectors.

Quoting DocLightning (Reply 82): CASM is important, but it has some important limitations.

  

Quoting seahawk (Reply 83): CASM is a result made from operating cost divided by seat numbers and both numbers are very specific for each airline. Saying CASM is king today can easily be corrected to "fuel burn is important", because that is what is actually meant in this debate.

   True. CASM and fuel burn are both part-of-the-picture metrics. Airline, however, need to complete the entire jigsaw puzzle before they can make commercially sensible acquisition decisions.

Quoting Matt6461 (Reply 79): Quoting Pihero (Reply 79): I asked you to provide one source that proves that the A380 has a stronger wake than a 744. Good Lord, Pihero. The source is every single aviation regulatory agency.

Then show one.
You'll discover that these separations ( note : not details of the wake ) come from an ICAO recommendation .

Quoting rheinwaldner (Reply 81): Quoting Pihero (Reply 79): the acquisition cost is totally embedded in the DOC I was not sure about that. But then that means that it is also reflected in CASM

*Reflected* is the word. CASM is an over-simplification of some very detailed and important calculations by the airlines. It is just a by-product, and not very accurate at that.
How can one lump in the same sheet First / Business / Premium and economy seats is a bit stretching the reality.
What the airlines are concentrating on is *yield* :
Look for instance at the easiest comparison : LCCs.
RyanAir business case is about cheap flights from *regional* airports in which they get some preferential terms from the locals.
EasyJet operates from big airports at which they pay much bigger fees - landing / assistance / Rents / Parking...etc... and they went to the jugular of established airlines, taking away a godly part of their business clients.
So, in terms of *CASM*, RyanAir is unbeatable here in France, both in terms of costs and in terms of number of seats / aircraft.
Guess what ? In France, RyanAir has lost one million passengers last year to EasyJet and Vueling and now Transavia is progressing.
Guess what ? RyanAir is forced to change - very late - their business model... but it's an up-hill struggle.

Quoting DocLightning (Reply 82): OK, what is the CASM of the 77W? Simple question. Answer it.

The CASM of the 77W is the total worldwide fleets DOC divided by every mile flown and divided by every installed seat. A number that can be determined with 10 significant digits if you like.

To use it for comparison we would fix a number of the cost blocks (or put in average values, e.g. for salaries). Once you do that you can compare the CASM of the 77W perfectly well with the CASM of e.g. the A351 and draw valid and important conlusions.

Quoting DocLightning (Reply 82): Because CASM is dependent on seat count. An AC 789 has a different CASM from an NH 789. Similarly, the Four Seasons 752 has a different CASM than a DL 752.

Of course. Use the average seat count on all 788's and the average seat count on the A332's and determine the CASM. You will immediately be able to explain the market share of the two.

Quoting seahawk (Reply 83): Saying CASM is king today can easily be corrected to "fuel burn is important", because that is what is actually meant in this debate.

I assume you mean fuel burn per seat. Anyway fuel burn is more simplistic than CASM. At least CASM considers some other cost blocks which are relevant for aircraft comparison:
- acquisition cost
- weight dependend fees
- ...

Quoting speedbored (Reply 84): Quoting rheinwaldner (Reply 81):There is no example of an aircraft that consistently kept up market share if it had a CASM disadvantage > 5% or so against another very similar aircraft. Can´t think of a single one... That may be true but the fact that you required the ">5%" qualifier proves my point;

Nobody said that CASM would be the only factor that counts. But with only 5% wiggle room there is not much space for other factors to play an important role. And that proves the point I try to make.

If only within a +/-5% bandwith other factors get relevant, CASM proves to be the ideal metric for the purpose of the typical A.net thread: making high level comparisons and predictions.

Quoting rheinwaldner (Reply 86): I assume you mean fuel burn per seat. Anyway fuel burn is more simplistic than CASM. At least CASM considers some other cost blocks which are relevant for aircraft comparison: - acquisition cost - weight dependend fees - ...

No, I mean fuel burn. The number of seats to be installed is something the airline interested in the plane should know. And I dare say nobody here is an position to disclose the real acquisition costs.

Quoting rheinwaldner (Reply 86): If only within a +/-5% bandwith other factors get relevant, CASM proves to be the ideal metric for the purpose of the typical A.net thread: making high level comparisons and predictions.

In the end it is just a more "averaged" version of trip costs per m² floor space and as such gives totally falls indications, especially when you start comparing planes by CASM, because most statements made about CASM in the public are just of no worth. Just think of the UA 787 in 3-3-3 which is said to have a CASM comparable to an A380. The question is what a A380? The 11 abreast, the 10 abreast, 2 class, 3 class, ......Would they have the same RASM? Would people pay more for the 10 abreast A380?

And if you then start with such data to postulate that the A380MAX needs to have XX% lower CASM to be competitive it is just esoteric guess work as it ignores so many parameters important for the acquisition of an aircraft that come into play way before you start talking about operational costs. Things like demand, frequencies, slots, gate availability, etc..

If we look at a route with a daily demand of 250 pax the A380 could have 40% lower CASM and you would not use it. If you have a perfect slot time at point X but no available A380 gate at the time, you won´t use it.

Quoting rheinwaldner (Reply 86): But with only 5% wiggle room there is not much space for other factors to play an important role.

Yes but that 5% "wiggle room" doesn't mean it only happens 5% of the time. Given that the CASM differences between the various aircraft that would be considered during an aircraft acquisition project are usually in the low single digits, that "wiggle room" comes into play in the majority of those decisions. A 5% CASM difference can quite easily be exceeded by differences due to "other factors". For example, just a 5.5% seat count difference would wipe that out entirely, all else remaining equal.

Quoting rheinwaldner (Reply 86): If only within a +/-5% bandwith other factors get relevant,

True but when the CASM difference between comparable aircraft rarely exceeds single digits then that becomes the majority of the time.

Quoting rheinwaldner (Reply 86): CASM proves to be the ideal metric for the purpose of the typical A.net thread: making high level comparisons and predictions.

That could be true, were there a sensible agreed standard for the definition of CASM, and it was always used with comparable seat densities, on average route ranges, but keeping well away from the sloping parts of either aircraft's payload-range graph. Unfortunately, that is rarely, if ever, the case, so CASM currently on A.net only proves to be the ideal metric for someone with an agenda.

Quoting speedbored (Reply 80): Got to admire your self-confidence, no matter how misguided: http://www.boeing.com/commercial/747...hts/technologically-advanced/wing/ "New State-of-the-Art Wing" http://www.flightglobal.com/news/art...al-description-amp-cutaway-378866/ " effectively all-new - but similarly sized - wing". https://en.wikipedia.org/wiki/Boeing_747-8 "the new wing" http://www.boeing-747.com/everything.../Boeing-747-8-new-wing-design.html "new wing design" http://airwaysnews.com/blog/2015/02/...intercontinental-airline-delivery/ "Boeing claims the new 747 has the world’s most modern ‘wing/engine’ airliner platform, with raked wingtips on an entirely new wing design"

I never took you for being a credulous Boeing partisan, so it's suprising to see you quote Boeing marketing shtick. If you had read the whole FG article, you would have seen:

Quote: Dickinson says that "fundamentally, the wing's structural design is not entirely different" from earlier variants

I.e. it's not an all-new wing.

Boeing elsewhere calls the 747-8i wing "significantly enhanced," whereas Airbus says it's the "same old wing" as the 747-100.

http://www.flightglobal.com/news/art...8-vs-a380-a-titanic-tussle-205137/

Quoting speedbored (Reply 80): Need I go on?

You need to concede. I admit when I have been incorrect, please be enough of a man to do yourself. We don't need to waste any more forum space or time on this issue.

"The wing is key to this airplane, combined with the GEnx engines, and what makes it so dramatically different from its predecessors," says Dickinson. "There's the advanced technology airfoil with the supercritical wing and raked wingtip designed using computational fluid dynamics, giving it the same technology level as the 787 wing. It is extremely efficient."

http://www.flightglobal.com/news/art...al-description-amp-cutaway-378866/

Quoting speedbored (Reply 80): Just because all of the components that you require to calculate CASM exist in the decision making process that I describe does not mean that you can make the decision based on CASM.

Again you're missing the distinction between (1) an analytical tool that is predictive/descriptive of a decision process, and (2) tools actually used in the decision process itself. Maybe my baseball analogy doesn't work across the pond.

At the very least, CASM is highly predictive of airline's decision-making outcomes, even were it not used in the actual process. Therefore, one can make predictions about airliner sales based on their CASM.

Quoting speedbored (Reply 80): The reason why CASM is never used in the decision making process is because it is not a required step in the calculation of likely profitability, which is what any publicly listed airline is legally obliged to base their decision on.

See above. "Never used in the process" isn't what were talking about, as I and Rheinwaldner, at least, have pointed out. We're talking about high level descriptions. The actual sales of actual airplanes turn out to be highly influenced by CASM.

Sometimes people who are engaged in a process have difficulty viewing said process analytically from 30,000 feet, so to speak. This is one reason strategic consulting firms make money. Perhaps you're in that situation, Speedbored - too deep in the weeds to see some big trends.

Quoting speedbored (Reply 80): Quoting Matt6461 (Reply 80): It is true that, in some circumstances, a bigger plane with higher CASM will be the best choice. So you admit that you are wrong then? Or are you just contradicting yourself?

See above. We're talking about high-level description of aircraft. Does the fact that the 748i sold a few dozen frames disprove my thesis that CASM is strongly predictive of sales? Of course not. If it had sold well, that would disprove my thesis, certainly.

Quoting speedbored (Reply 80): I notice that you completely ignored the two questions

Which ones specifically? You should know that I don't respond to all of your points all the time. Especially when I feel like I've already addressed them.

Quoting rheinwaldner (Reply 81): I am not exactly sure why anyone would doubt that CASM is an absolute key metric comparing the efficiency of aircraft operations.

...and I would add, just to clarify in anticipation of Speedbored's rejoinder, of aircraft themselves. Maybe we'll convince him after all this.

Quoting Matt6461 (Reply 89): If you had read the whole FG article, you would have seen: Quote: Dickinson says that "fundamentally, the wing's structural design is not entirely different" from earlier variants I.e. it's not an all-new wing.

I did read the whole article, thanks. I also fully understood it. "not entirely different" is absolutely not the same as "the same".

When it comes to aircraft, every all-new design has many aspects of its structure that are "not entirely different" from those that have gone before. That does not make them "reworks on old bones".

Even if you want to go with a strict definition that any structural similarity rules it out from being called "all new", it is most definitely far more of a new wing than the "reloft on the bones of a '70's wing" that you claim it to be.

Even if Airbus did foolishly decide to go ahead with your proposed all new wing, it would, by necessity, have to have many structural similarities to the existing wing because it still needs to attach to the existing wingbox. Would that make your proposal a "rework on old bones" too?

Quoting Matt6461 (Reply 89): I admit when I have been incorrect,

Oh don't make us laugh. You have been incorrect on so very many occasions and I only ever remember seeing you concede once. And that was the embarrassingly bad wing twist "mistake". Usually when you realise you are wrong, rather than admitting it, you try to divert the discussion off on a tangent.

Quoting Matt6461 (Reply 91): Again you're missing the distinction between (1) an analytical tool that is predictive/descriptive of a decision process, and (2) tools actually used in the decision process itself.

I'm not missing anything. I get contracted by airlines specifically because I fully understand all aspects of these processes.

Quoting Matt6461 (Reply 91): At the very least, CASM is highly predictive of airline's decision-making outcomes

No, it is not. Otherwise all the airlines would be flying A380s.

Quoting Matt6461 (Reply 91): Sometimes people who are engaged in a process have difficulty viewing said process analytically from 30,000 feet, so to speak. This is one reason strategic consulting firms make money. Perhaps you're in that situation, Speedbored - too deep in the weeds to see some big trends.

Oh give me a break. I am one of those consultants. I get contracted by airlines specifically because I can provide a purely objective, analytical view of things, without all the preconceptions that many airline employees will have.

The idea that you, with zero industry experience, can see things more clearly than the many people on here with very considerable knowledge, based on ears of experience, is frankly laughable.

Quoting Matt6461 (Reply 91): The actual sales of actual airplanes turn out to be highly influenced by CASM.

No, actual sales of aircraft are almost entirely influenced by how much money they are projected to make for an airline. CASM does not influence the process at all, let alone highly. CASM is merely an output from the process, not an input.

Quoting Matt6461 (Reply 91): Which ones specifically? You should know that I don't respond to all of your points all the time. Especially when I feel like I've already addressed them.

Seems to me that you mostly ignore them when answering them would be inconvenient to your agenda. But how about trying this one?:

Quoting speedbored (Reply 77): Given that, for publicly listed airlines, airline management are legally obliged to only make decisions that they believe will maximise shareholder value, perhaps one of the CASM-is-king proponents could explain to us exactly how they can fulfill that obligation if they make their aircraft purchase decisions based on CASM, and not based on projected profits?

Quoting speedbored (Reply 92):

Reference is made once more to the following chart:



Note that the figures and terms in the chart are Boeing's. Note that, on the left-hand side, under "747-8," the term used is "Significantly enhanced wing," whereas in the middle column, under "A380," the term used is "all-new wing."

Now why would Boeing use "all-new wing" for its competitor, and not for itself, if the 747-8 had a new wing?

Note also that the 748 has a lower effective aspect ratio than the A380, which even its designers admit has suboptimal AR:



What could possibly explain Boeing's retention of suboptimal wing design - stubbier even than A380's stubby wing - if they designed a new, unconstrained wing? Please no "Boeing is dumb" comments from the peanut gallery btw. The only explanation is one I've given - that it's an old wing, relofted with tip extensions. My explanation also happens to concur with the facts.

You really need to concede this point. It's a waste of time.

Quoting speedbored (Reply 93): The idea that you, with zero industry experience, can see things more clearly than the many people on here with very considerable knowledge, based on ears of experience, is frankly laughable.

Not more clearly than "the many" here, probably. More clearly than you, though - yes on this point and a few others I would say so. Your arguments are all you bring here, and they're unconvincing. If you're advising your clients that it doesn't really matter how efficient planes are, per seat, then...

Quoting speedbored (Reply 93): Given that, for publicly listed airlines, airline management are legally obliged to only make decisions that they believe will maximise shareholder value, perhaps one of the CASM-is-king proponents could explain to us exactly how they can fulfill that obligation if they make their aircraft purchase decisions based on CASM, and not based on projected profits?

Here again you're attributing an argument that I haven't made. You're saying that I have somehow been arguing that profit doesn't matter. I think everyone sees this is laughable. Everywhere I have said that the A380 is best on CASM right now, but not good enough on CASM for its size. I have repeatedly posted about capacity/efficiency tradeoff and the efficiency level at which the A380 should be on the capacity/efficiency curve. This is a question of yours I didn't answer because it misrepresents my views, quite transparently.

For a long time I didn't engage with you at all on the forum. We have now had a long series of exchanges in which the same pattern is repeated - you misrepresent, oversimplify my views, refuse to concede demonstrably wrong points. I'm hoping that this exchange will have been worthwhile for some readers. To those that are annoyed by it, I apologize. I do think it's important to push back on the idea that planes can't be compared for efficiency purposes.

Among other things, that's much of what the OEM's do, at least in their public presentations - compare seat-mile costs. Surely the preceding sentence will elicit a response from Speedbored about how only industry insiders know that this is irrelevant talk - that customers don't see any meaning in it. That can't be true considering that Airbus went to the trouble of suing Boeing over A380 vs. 748 public statements about CASM. And that OEM's pay high level officials to make frequent presentations comparing CASM between their respective offerings. They clearly judge CASM comparisons as being worth their time and money. Are you, Speedbored, of such stature as to know better than the OEM's? This whole argument strikes me as a bit ridiculous. But, nonetheless, it's important to shoot down ridiculous ideas. I just wish it were easier and less time-consuming.

Quoting Matt6461 (Reply 91): At the very least, CASM is highly predictive of airline's decision-making outcomes, even were it not used in the actual process. Therefore, one can make predictions about airliner sales based on their CASM.

But a major factor in CASM is the number of seats.

Would the 777-300ER have been as successful against the A340-600 if most 77W operators went with ANA's 212-seat configuration and most A346 operators went with Lufthansa's 306 seat configuration?

People argue that the A380's CASM at 500 seats is bad, so one would think Korean's A380 must have horrifically bad CASM operating the plane with only 400 seats and their 747-8's must crush the A380 on CASM since they have 368 seats in a lighter frame. Yet I imagine the 50% more First and (almost) 100% more Business Class seats on the A380 must do wonders for the per trip revenues compared to the 748...

[Edited 2015-08-11 10:27:05]

Quoting Stitch (Reply 96): But a major factor in CASM is the number of seats.

That's why CASM comparisons must be made according to standardized rules. Or just use cabin area. Or use cabin area with some adjustments for seating density at standard rules (e.g. a 10-abreast 77W will have more seats per m2 than A380 at 10-abreast). That's how Leeham, Airwaysinsight do comparisons. It's how the OEM's claim to do CASM comparisons, though of course they fudge in self-interest.

At the margins, different configurations will effect CASM comparisons. For example:

-If the rules are 4-abreast J-class seats, the picture will be slightly more favorable to A380 than if 6 or 7 abreast is allowed. This is because A380's upper deck is better for 4-abreast than 777's, especially now that Airbus has removed the side bins, allowing for lower seat pitch in herringbone configuration with seats facing outwards.

-I would expect the above differential to make, at most, a 2% difference to the CASM picture versus using 6/7-abreast J class seating. It's significant, and any sales campaign would account for it, but for our purposes it's already "priced in": the A380 is being offered without the bins on the market, and so far nobody is buying. So whatever its CASM advantage, it's not good enough to convince airlines to buy A380's.

I'd also like to remind everyone that the raison d'etre for the A380NEO is to reduce its CASM. Airbus hopes to convince airlines who won't buy CEOs to buy NEOs. Their only selling point in this exercise is lower CASM. Thus the "comparison" between the CEO and NEO is entirely about CASM.

That preceding paragraph is another case that feels ridiculous to have to write. To have to remind people that per-seat efficiency actually matters, to actually have this debate, feels ridiculous. But I guess it's important - I just didn't realize that some folks think there is an actual debate here.

[Edited 2015-08-11 10:29:41]

Quoting Matt6461 (Reply 97): That's why CASM comparisons must be made according to standardized rules.

But how do you do that considering the "cost" in Cost per Available Seat Mile has many variables and those costs differ between carriers?

Quoting seahawk (Reply 74): CASM is not a parameter you can use to compare aircraft types in general.

   I think the sticking point is that sometimes people believe that CASM is an intrinsic property of an airplane, like maximum take-off weight or wingspan. It isn't.

Quoting Matt6461 (Reply 97): I'd also like to remind everyone that the raison d'etre for the A380NEO is to reduce its CASM.

I thought it was about increasing profit? (As you know, "profit" is step three of any cunning plan).