Aircraft empty weight vs number of passenger seats

[Gilles Hudicourt]

Aircraft manufacturers keep producing new designs that are much more fuel efficient than older ones, using lighter materials (composites), better aerodynamics (new wings and winglets), more fuel efficient engines and other methods as well (lack of bleed air for packs in the 787 for example).

I would like to take a look at the weight savings aspects, by comparing the Operating Empty Weights of actual fleet aircraft and dividing it by the number of passenger seats installed in that particular configuration, the see how many Kilograms of aircraft empty weight it takes to haul one passenger. All other things being equal, the lightest aircraft should be the most fuel efficient. Of course long haul aircraft are built heavier than short haul aircraft.

Please post the actual Operating Empty Weight of your aircraft and the number of passenger seats installed in it, and divide the weight by the number of seats. We'll see which are the heavier aircraft and which are the lightest. Am interested in having all airline types, from older 737-200s, 737-200s, to MD-80s, right up to the 787s and Emb 195s.

Are the older types like the 727-200, MD-11s and 747-400s that much heavier than more modern aircraft such as the B777, A330, the Emb 195 and the 787 ?
How does a 737-800 compare in empty weight per Pax to an Airbus 320 ?
How does a 747-800 compare to an A-380 ?

Of course the configuration (number of seats) varies greatly on the same aircraft type from one operator to another, and that will change the results, but hopefully with enough data, we will be able to make valid comparisons.

Please post the Operating Empty weight - Revenue (including crew but not the catering) of your aircraft and the total number of passenger seats, and divide the weight by the number of installed seats.

Example :

Airbus 330-200 OEW 118,500Kg, 342 seats (12+330) = 346.5 Kg/Pax
Airbus 330-300 OEW 120,400Kg, 342 seats (12+330) = 352.0 Kg/Pax

[C_Star]

Airbus 320 OEW 42050Kg, 180 seats = 233.6 Kg/Pax

[kenparry]

A few examples from high-density European charter flying in the 90s:


B757-200 APS weight 59750kg, 235 seats, 254kg/seat
B767-200 APS weight 83200kg, 274 seats, 304kg/seat
B767-300 APS weight 91500kg, 344 seats, 266kg/seat

NB: APS weight includes crew and galley stores, for which I no longer have figures

[DaveReidUK]

An hour with Google and the OP would have had a pretty comprehensive graph by now.

[Gilles Hudicourt]

An hour with Google and the OP would have had a pretty comprehensive graph by now.

I thought of that but the manufacturer's empty weight as published on web sites is often far from reality and does not necessarily reflect the actual interior configuration. I was after real life numbers.......

[barit1]

Over the years, OEW has come down due to better materials, etc. But at least as much weight has come out of the fuel carried. A few percent per year over the decades; This is at least as significant as the structure weight!

[Gilles Hudicourt]

Over the years, OEW has come down due to better materials, etc. But at least as much weight has come out of the fuel carried. A few percent per year over the decades; This is at least as significant as the structure weight!

I left fuel out of this one precisely to see if structural weight has decreased proportionally, to see if newer aircraft are lighter per passenger than older ones. It remains to be seen....

I hope many people will reply with their aircraft's figures.....

[No Fly Zone]

@ G. H.:
You've already seen a few numbers. THe more detailed stuff varies a lot from model to model and airline to airline. In many cases, it is very closely guarded detail that darn sure will not publish. In your shoes, I'd be happy with what you've already been given, not expect much more and move one. As you can imagine, (should know) much if this operating data is closely held, competitive detail; the carriers darn sure won't release these data to you, a unknown, without darn good reason. YES! The carriers collect, maintain and use these numbers for their own, internal purposes. Disclosing this kind of fine detail to an outside visitor is just Not Going to Happen. I won't call these details truly "Secret," but you are getting very close to items are truly are competitive secrets. If nothing else, perhaps pose you question in a different way? Good luck. You are treading on seriously tender ground and that quick and easy answer is just not there. -NFZ

[Stampe]

The B788 Dow about 119.4/291 pax = 410 kg per seat...all those generators weigh a lot.vbr Stampe

[Skyjob]

The manufacturers empty weight on their websites could well be used by the OP as weight in cabin is roughly proportionate to number of seats installed in many cases.

Apart from this, like mentioned before, most companies hold the exact detail of cabin fixtures and fittings close to their chest. After all, it give competitors an insight into how weight is managed by their competition.

Structural limitations are known, manufacturers empty weights known, number of seats can be Google'd, thus a comparison can be made. Taking into account that maybe not all seat can be fully occupied when operating at MTOW in certain scenarios, it still gives a good starting point and insight.

[SMOC]

EK 380 = approx 510kg per pax
CX 747 = approx 490kg per pax

[Gilles Hudicourt]

I found the Boeing 737-800 42,300Kg @ 189 Pax = 223.8Kg/Seat

So far:

Airbus 320 234 Kg/Seat
Airbus 330-200 346 Kg/Seat
Airbus 330-300 352 Kg/Seat
Airbus 380 510kg/Seat
B737-800 224/Seat
B747-400 490kg/Seat
B757-200 254kg/seat
B767-200 304kg/seat
B767-300 266kg/seat
B787-800 410/Pax kg

Interesting no ?

I hope we get more........

[Ditched]

Interesting to see that the 787 is heavier per seat by about a 100kg than the 767 it is supposed to be replacing. Guess all these weight saving technologies are eh.... really heavy.

[Gilles Hudicourt]

The manufacturers empty weight on their websites could well be used by the OP as weight in cabin is roughly proportionate to number of seats installed in many cases.

[URL="http://www.airbus.com/fileadmin/media_gallery/files/tech_data/jetFamily/media_object_file_A330_200_specifications.pdf"]

Typical operating weight empty 127,750 kg

this weight may be true and realistic for certain configurations but it is over 9 metric tonnes over a real life A330-200 that I found. This is why I am looking for real life data.

[Gilles Hudicourt]

Interesting to see that the 787 is heavier per seat by about a 100kg than the 767 it is supposed to be replacing. Guess all these weight saving technologies are eh.... really heavy.

Remember, it depends on the number of seats installed. Some Airbus 330-200s have 264 seats. Others have over 400, so the config has a LOT to do. This comparison will only be fair when a high density seating 767-300 is compared to a high density seating 787-800........

[FE Hoppy]

Not sure how useful these stats are.

Fuel per passenger mile is surely much more useful.

[Ditched]

From the info available on the boeing website,

767-400ER 296 pax 2 class OEW 103872 (351 kg/pax)
787-8 242 pax mixed 3 class OEW 117798 (487 kg/pax)

even if you would fit the same number of pax (296) in a 787-8 its still heavier by about 50 kg per seat.

[KBPsen]

Not sure how useful these stats are.

I also wonder what the point is or what is interesting. All it tells us is that aircraft gets exponentially heavier with size. Which is old news.

[CargoOne]

Winners will be 320/321, 738/739 and 753 all in high density configs.
When you are very close in numbers there are always some small elements - for example a320/321 with v2500 will be heavier than with cfm56. Around seats options now there is a titanium frame bench which is twice lighter than typical triple seat block. There are a320 with only 2 toilets iso normal 3.

Widebodies are always heavier per seat.

[Denti]

A lot depends on specific configuration. For example we have two different configurations of A332s in our fleet, one is configured in an all economy style with 340 seats and weighs 121.993kgs empty which comes out at 359kg and the other one has 19 business and 279 economy seats with an DOM of 122.232kg which equates to 410kgs per seat. Same basic aircraft, different weight. The difference between our 180 seat A320s and our 12/132 seat A320s might be even bigger, but i'm too lazy to look up the numbers.

Just for comparison: Dash 8 Q400, 76 seats, 18.472kg DOM, 243kg/seat.

[Capot]

To prove the point, here's a blast from the past; the VC10 was possibly the best example of prioritising strength and performance over commercial reality (leaving SST on one side). I think that these numbers are reasonably typical;

Weight ("Operating empty" ie APS)
Standard 66,670 Kg
Super 71,137 Kg

Seats
Standard 109 in 2 classes
Super 139 in 2 classes

Weight per seat
Standard 611 Kg
Super 512 Kg

By way of contrast, the contemporary B707-320B had a typical APS of 66,406kg, with typical 2-class configuration of 147, thus 452 Kg per seat.

A DC7C was about 345 Kg/seat APS. A C172 is about 150 Kg/seat empty. The longer DC8 variants were about 345 Kg/seat APS, with max seating.

However......B787-8 with 457 Kg/seat APS pretty much matches the B707-320B with 452 Kg/seat, built about 50 years ago, if my figures and the figures provided in this thread are right.

And the stretched DC8s were far lighter per seat, at 345 Kg/seat APS.

B747-400 is about 435 Kg/seat APS, depending on configuration.

Airbus A380 is 499 Kg/seat APS.

All these numbers are dependent on configuration, but the main thrust of the argument doesn't change significantly when actual operating aircraft/fleet configurations are looked at.

So the APS/empty operating weight per seat seems to be increasing slightly for long-haul aircraft, in spite of all the new lightweight construction materials etc. Ditched has also pointed this out.

This came as a great surprise, when I started looking at older aircraft to illustrate the point that weights are coming down, only to find that they are not.

Now why is that?

[oceancrosser]

From the info available on the boeing website,

767-400ER 296 pax 2 class OEW 103872 (351 kg/pax)
787-8 242 pax mixed 3 class OEW 117798 (487 kg/pax)

even if you would fit the same number of pax (296) in a 787-8 its still heavier by about 50 kg per seat.

Makes you wonder how much the 788 would have weighed had it been an aluminum airplane...

To prove the point, here's a blast from the past; the VC10 was possibly the best example of prioritising strength and performance over commercial reality (leaving SST on one side). I think that these numbers are reasonably typical;

Weight ("Operating empty" ie APS)
Standard 66,670 Kg
Super 71,137 Kg

Seats
Standard 109 in 2 classes
Super 139 in 2 classes

Weight per seat
Standard 611 Kg
Super 512 Kg

By way of contrast, the contemporary B707-320B had a typical APS of 66,406kg, with typical 2-class configuration of 147, thus 452 Kg per seat.

A DC7C was about 345 Kg/seat APS. A C172 is about 150 Kg/seat empty. The longer DC8 variants were about 345 Kg/seat APS, with max seating.

However......B787-8 with 457 Kg/seat APS pretty much matches the B707-320B with 452 Kg/seat, built about 50 years ago, if my figures and the figures provided in this thread are right.

And the stretched DC8s were far lighter per seat, at 345 Kg/seat APS.

B747-400 is about 435 Kg/seat APS, depending on configuration.

Airbus A380 is 499 Kg/seat APS.

All these numbers are dependent on configuration, but the main thrust of the argument doesn't change significantly when actual operating aircraft/fleet configurations are looked at.

So the APS/empty operating weight per seat seems to be increasing slightly for long-haul aircraft, in spite of all the new lightweight construction materials etc. Ditched has also pointed this out.

This came as a great surprise, when I started looking at older aircraft to illustrate the point that weights are coming down, only to find that they are not.

Now why is that?

Hmm. Went digging a little bit, found numbers for the DC-8-63s I flew in the mid-late eighties:

Operating empty wt around 74.800 kgs, all Y was 249 seats, so 300 kgs pr seat. Later we had business class installed, and went down to 234 seats, OEW did not change much so it would still be only 320 kgs pr seat.

[Cough]

Take the 737-300 and the -700

Similar fuselages (-300 length is 33.4m, -700 is 33.6m) seating approx the same.

OEWs

-300 - 32,700kg
-700 - 38,100kg

So same fuselage, but 5.5T heavier...Must be the wing....28.9m compares to the NG with 35.7m.

But what do you get with it? Another 2 -> 9 T of payload (option dependent) with a significant fuel burn advantage.

But the OEW vs seats installed doesn't show that...Its all about the wing/engine efficiency...

[Wunwing]

While the weight/pax may tell part of the story and from this it is smaller aircraft have a lower weight/pax it doesn't tell anything about freight which is a large part of the overall profit on long haul.

Part of the reason larger aircraft weigh more per pax is that they are not optimised for pax weight, but over all profit which includes a large amount of underbelly cargo. This includes the on board handling equipment like strenghened floors, rollers,tie downs, cargo doors and power distribution needed for all this.

[Capot]

Good point, Wunwing, but maybe only if the cargo volume (and/or the payload available with 100% passenger L/F) per passenger seat has been increased significantly over the years.

The older aircraft also had much of what you describe, but not roller beds as I recall, which along with special cargo doors were found only on cargo aircraft, or combis, and I suspect that's still true.

I'm not sure that power distribution for freight handling purposes is a big weight factor on passenger aircraft.

But I'm sure you are right, and the volume and payload available for freight with a full passenger load could well have increased, thus keeping the total empty weight per seat where it was. Do you have any numbers? I don't.

[Wunwing]

No I don't have any current data but a number off comments on this thread seem to be looking at a formula based on aircraft empty weight divided by number of seats and coming to a conclusion of efficiency.

Any modern widebody will have the same inbuilt "inefficiency" on that basis, as all longhaul widebodies will have a fair amount of underbelly freight capacity which may or may not be able to be utilised fully depending on range, market and airport limitations.

A B747 for instance has 3 underbelly freight doors and they are quite large compared to B737/A320. All B747s since the 100 have had powered rollers in the belly. All that requires substantially more wiring, power distribution controls etc than a small pax aircraft. However the fact that is is still there over 45 years of B747 production would seem to indicate that it generates substantial revenue beyond handling the "cans' for pax baggage which only fill one of the 3 holds.

So overall a simple empty weight divided by pax only tells part of the story and any conclusions based on that are far from accurate indication of aircraft type or airline profitability.

[Anti Skid On]

A couple of thoughts re. the 787 and the fuel savings; whilst the airframe appears heavier, how much of that equates to fit out? All that IFE equipment is pretty hefty and wasn't present in a 70's airframe. The majority of the 787's fuel savings come from drag reduction and the lack of stealing bleed air for pressurisation.

The A380, it should be remembered that it carries a load of freight payload per revenue flight, which isn't costed into the passenger v kg figure.

Anecdotally I was told that when Air NZ stuck winglets on their 763's (soon to be replaced with 789's) they also sent them away to remove excess water from the insulation. The figure quoted was there was approximately 3000kg of water accumulated in each aircraft - more than made up for the weight of the new winglets.

[B-HKD]

Anecdotally I was told that when Air NZ stuck winglets on their 763's (soon to be replaced with 789's) they also sent them away to remove excess water from the insulation. The figure quoted was there was approximately 3000kg of water accumulated in each aircraft - more than made up for the weight of the new winglets.

They added a Zonal Dryers (made by CTT of Sweden) which added approximately 30kg in weight to save 200kg/aircraft. Removes excess humidity from insulation (from passengers exhaling).

Boeing elected to make it standard equipment on the 787-8/
9/10 and offers it as Buyer Furnished Equipment on B737NG, B767, B777, 787.

Airbus is also offering it as a customer option on the A350.

Flydubai has also installed Zonal Dryers on all their 737s.

[Gilles Hudicourt]

I was told that when an A380 is full of passengers that the hold generally nearly bulks out, leaving little room for freight.

The purpose of this excercise is not to compare widebodies to narrow bodies but to compare aircraft of the same category against each other, as far as empty weight, especially older models to newer ones.

I would like to see the numbers for older 747 (-200 and -300) as well as DC-10, MD-11 and L-1011s.

Of course one would have to look at other figures such as the relation between an aircrafts' OEW and its MZFW, and also the relation between the OEW, the MZFW and its MTOW, for significant inceases in the two latter numbers may explain an increase of Empty weight.

Comparing Wiki numbers for the 737-900 and the 757-200. Same manufacturer, same fuselage cross section. The 737-900 is 42.1 meters in length and can carry a max of 220 pax in a single class high density config.
It is listed at 44,700 Kg, which would give it 203Kg/seat.
The 757-200 is 47.3 meters long and can carry a max of 239 passengers. It is listed at 57,800 Kg, which would give it 242 Kg/seat.
No wider holds. No wider fuselage. The difference seems to be in the metal required to reach 115 tonne MTOW, vs 85 tonnes for the 737-900.

There was a time when some manufacturers made wide body medium range aircraft. The Airbus 300-B4s, the A300-600, the A310-200 and the early B767-200s which were mostly used on short domestic routes and were not ETOPS. No such aircraft are being built today.
However, today, it seems more economical to dispatch two 737-700s back to back to a single short range destination than to cover the same short route segment with a larger aircraft having the same seating capacity as the Boeings put together. This was a surprise to me when I discovered it.......

[OverRun]

The missing part of this discussion is range, although several people have hinted at it. Simple tabulation of aircraft and weight per seat is not helpful. What is needed is a graph of weight/ seat vs range. Then the long hauls will separate out from the short hauls and a better picture of change over time will emerge.

[Gilles Hudicourt]

Airbus 320 234 Kg/Seat
Airbus 330-200 346 Kg/Seat
Airbus 330-300 352 Kg/Seat
Airbus 380 510 kg/Seat
B707-320B 452 Kg/seat
B737-300 234 Kg/seat (@140 seats)
B737-700 272 Kg/seat (@ 140 seats)
B737-800 224 Kg/Seat
B747-400 490 kg/Seat
B757-200 254 kg/seat
B767-200 304 kg/seat
B767-300 266 kg/seat
B767-400ER 351 kg/seat (Source Boeing Website with 296 seats @ 103872Kg)
B787-800 410 Kg/Seat kg (Source Stampe at 291 seat @ 119.4 OWE)
B787-800 487 kg/seat) (Source Boeing Website with 242 seats @ 117798)
DC7C 345 Kg/seat
DC8-61 345 Kg/seat
DC8-63 300 Kg/seat (@249 seats)
DC8-63 320 Kg/seat (@234 seats)
Q400 243 kg/seat (76 seats @ 18.472kg DOM)
VC10 611 Kg/seat
VC10 Super 512 Kg/seat

Anyone notice which is the lowest in this list so far ? The B787-800, followed closely by the A320. Surprise anyone ?

I hope more people contribute.......

[Peter47]

Here is data from an old spreadsheet that I have in my possession but it doesn't include the newer types. Apologies - the system seems to reduce everything to a single space not making this clear. I'll PP you the spreadsheet.

Type Engines Seats OEW kg kg/seat
A 300-600 CF6-80C2A5 212 90,300 426
A 310-300 CF6-80C2A8 192 79,666 415
A 318-100 CFM56-5B 81 39,035 482
A 319-100 CFM56-5B6 96 40,350 420
A 320-200 CFM56-5B4 109 42,100 386
A 321-200 CFM56-5B3 132 48,140 365
A 330-200 CF6-80E1A4 236 120,500 511
A 330-300 CF6-80E1A4 236 124,300 527
A 340-200 CFM56-5C4 225 125,650 558
A 340-300 CFM56-5C4 260 129,850 499
A 340-500 Trent553 269 170,300 633
A 340-600 Trent556 294 176,900 602
B 737-500 CFM56 3C1 76 31,950 420
B 737-300 CFM56 3C1 91 31,869 350
B 737-400 CFM56 3C1 106 34,810 328
B 737-600 CFM56 7B22 76 36,900 486
B 737-700 CFM56 7B22 91 38,150 419
B 737-800 CFM56 7B27 121 41,150 340
B 737-900 CFM56 7B27 136 42,490 312
B 747-400 CF6 80C2B5F 250 183,810 735
B 747-400 CF6 80C2B5F 358 181,120 506
B 747-400X CF6-80C2B5F 358 183,810 513
B 747-400X GP7000423 190,500 450
B 757-200 PW2040132 58,390 442
B 757-300 PW2043162 63,650 393
B 767-200 CF6 80C2B8F 158 84,690 536
B 767-300 CF6 80C2B7F 194 90,540 467
B 767-400 CF6 80C2B8F 208 102,690 494
B 777-200 GE-90-94B260 143,790 553
B 777-200 GE-90-115B260 155,990 600
B 777-300 GE-90-95B336 158,480 472
B 777-300 GE-90-115B336 169,190 504
B 717-200 BR 715 C1-30 58 32,110 554
MD87 JT8D-217B74 35,003 473
MD83 JT8D-21994 38,737 412
MD90-30 V2528 D5 100 41,178 412
MD11 PW4460 268 132,800 496
CRJ-200 CF343B1 34 13,740 404
CRJ-700 CF348C1 49 19,731 403
RJ-70 LF 507 1F 65 23,600 363
RJ-85 LF 507 1F 77 24,380 317
RJ-100 LF 507 1F 92 24,750 269
ERJ-135 AE3007A 33 511,200 320
ERJ-145ER AE3007A 147 11,840 252

[Peter47]

I am also interested in fuel consumption per seat. As some of the previous posts have said it is important to quote like with like. I would suggest a metric of square metres of floor available floor area. It would also be necessary to convert hold space to an equivalent of this. For example a 77W has less space for passengers than a 774 but more hold space (obviously not relevant if there is not much freight around or ultra long range routes). Would it be possible to produce a graph of fuel consumption per m^2 of floor space by range. Has anyone got a link of anything is available on the web? (GH has said that published weight data is suspect - finding accurate fuel consumption data is even harder.)

[DaveReidUK]

Apologies - the system seems to reduce everything to a single space not making this clearTry this:

Type Engines Seats OEW_kg kg/seat
A300-600 CF6-80C2A5 212 90,300 426
A310-300 CF6-80C2A8 192 79,666 415
A318-100 CFM56-5B 81 39,035 482
A319-100 CFM56-5B6 96 40,350 420
A320-200 CFM56-5B4 109 42,100 386
A321-200 CFM56-5B3 132 48,140 365
A330-200 CF6-80E1A4 236 120,500 511
A330-300 CF6-80E1A4 236 124,300 527
A340-200 CFM56-5C4 225 125,650 558
A340-300 CFM56-5C4 260 129,850 499
A340-500 Trent553 269 170,300 633
A340-600 Trent556 294 176,900 602
B737-500 CFM56-3C1 76 31,950 420
B737-300 CFM56-3C1 91 31,869 350
B737-400 CFM56-3C1 106 34,810 328
B737-600 CFM56-7B22 76 36,900 486
B737-700 CFM56-7B22 91 38,150 419
B737-800 CFM56-7B27 121 41,150 340
B737-900 CFM56-7B27 136 42,490 312
B747-400 CF6-80C2B5F 250 183,810 735
B747-400 CF6-80C2B5F 358 181,120 506
B747-400X CF6-80C2B5F 358 183,810 513
B747-400X GP7000 423 190,500 450
B757-200 PW2040 132 58,390 442
B757-300 PW2043 162 63,650 393
B767-200 CF6-80C2B8F 158 84,690 536
B767-300 CF6-80C2B7F 194 90,540 467
B767-400 CF6-80C2B8F 208 102,690 494
B777-200 GE-90-94B 260 143,790 553
B777-200 GE-90-115B 260 155,990 600
B777-300 GE-90-95B 336 158,480 472
B777-300 GE-90-115B 336 169,190 504
B717-200 BR715C1-30 58 32,110 554
MD87 JT8D-217B 74 35,003 473
MD83 JT8D-219 94 38,737 412
MD90-30 V2528-D5 100 41,178 412
MD11 PW4460 268 132,800 496
CRJ-200 CF343B1 34 13,740 404
CRJ-700 CF348C1 49 19,731 403
RJ-70 LF507-1F 65 23,600 363
RJ-85 LF507-1F 77 24,380 317
RJ-100 LF507-1F 92 24,750 269
ERJ-135 AE3007A 33 511,200 320
ERJ-145ER AE3007A 147 11,840 252

[oceancrosser]

Not sure all the seat numbers add up. Where would you find a 752 with 132 seats and a 753 with 162 seats? Or a 717 with 58 seats?
Doesn't look plausible.

[Gilles Hudicourt]

Not sure all the seat numbers add up. Where would you find a 752 with 132 seats and a 753 with 162 seats? Or a 717 with 58 seats?
Doesn't look plausible.

I agree. I checked SeatGuru and found, for example, that a three class International 757-200 at American Airlines had 176 seats.....

[CONF iture]

BA operates the 318 at 32 seats.

[tdracer]

Nearly all the seat numbers look way to low - for example there is only one operator of the 757-300/PW2000 (Delta), two layouts, 224 seats and 234 seats.

[Gilles Hudicourt]

I entered some aircraft weights into a Spreadsheet that I am sharing here. Download it and play around with it.

https://dl.dropboxusercontent.com/u/105225711/Aircraft%20weight%20data.xlsx

The weights may not all be exact, I got them off the internet. You can correct them yourself if you find correct figures.
When I found different versions of same aircraft (ie a high gross and a low gross, I entered the heavier of the two)

There are six columns:
Aircraft Type
OEW
ZFW
MTOW
Payload (ZFW - OEW)
Useful Load (MTOW - OEW)

When you first download the spreadsheet, the aircraft will be sorted by aircraft type.

By sorting the columns by Payload and Useful Load, aircraft of similar payload or of similar useful load can be compared as far as OEW. Its an interesting exercise.

For example the Boeing 787-8 has a payload (in my spreadsheet) of 43,222Kg, just 1 tonne over the L-1011-500 which had a payload of 42,010Kg. It has a useful load of 110,132Kg, while the L-1011-500 has 120,200Kg.

The B787-8 has an OEW of 117,798 while the L-1011-500 has 111,300.

So the mostly carbon 21st Century 787-8 is 6.5 tonnes heavier than a late 1960s era L-1011-500.

Compare an MD-11ER and a B777-200 which have similar payloads, and the MD11ER is lighter by 8 tonnes in OEW while having a useful load that is 47 tonnes greater.

Comments ?

[ManUtd1999]

Modern aircraft have bigger, high BPR engines, which in turn weigh more. This increases OWE but it's worth it for the fuel burn advantages. That said, compared to some of the really old models engine weight might be ~neutral as structural enhancements will cancel out the extra size.

With all of these /seat calculations though it depends heavily on seat density. A high-density config will nearly always beat a long-haul config with business/first seating, regardless of the actual structural efficiency. Perhaps a measure of OWE per unit of cabin volume would better? But again this obviously wouldn't take into account fuel.

[OverRun]

Using the data from the spreadsheet of Gilles, the following graph indicates that the payload rises as the OWE increases. There is a sense of diminishing returns as the OWE rises, which reflects the increasing structural weight needed per kg of extra payload as the aircraft gets larger; it might also be related to range.

The black trend line deviates increasingly from the linear as the OWE increases. There is less scatter than I had expected from the discussion above.

There is the obvious exception with the Boeing 747SP.

http://profemery.info/seats2.jpg

Then when the aircraft are divided by range, they show the effect of fuel capacity on the OEW/payload relationship.

The aircraft have been divided into short range (<5000 km), long range (5,000 - 10,000 km), and ultra-long range (>10,000km). These are my arbitrary divisions, with divisions approximately at the 737-800 and 767-300ER ranges.

The linear trend lines show the differing OEW/payload relationships. As expected, the longer the range, the less "efficient" is the structural weight needed per kg of extra payload.

http://profemery.info/seats1.jpg

[Gilles Hudicourt]

Interesting. I'll try to get more reliable numbers and add more aircraft to the list, when I have time...

[mustangsally]

This whole discussion maybe a nice academic conversation but really only produce conversation not productive information. In some of the examples with a full load of fuel, moves the all the numbers. JAL at one time had 747's flying relatively short legs, but with something around or over 500 seats. Then throw in the 380, (one of the ugliest airframes in the sky, MHO) with a couple of showers with hot running water.


A better conversation would center around the direct operating cost of the airframe. The 777, 787 and maybe the 350 are fuel savers, that's why the airlines want them. The 380 maybe dead in less than five years, just cost to many liters of jet fuel to move the beast.
Fuel cost per seat would be a much better conversation. Or, how about cost per hundred kilos?


As long as the aircraft is above a relative size the passenger is more interest in frequency, than number of seats it carries. An airline offering four departures a day in a 737/320 as opposed to one 330 departure.
The 737/320 carrier wins.


Just my couple of pennies.

[Australopithecus]

You have to look at total cost per ASM (ASK), not just fuel. Certainly the 380 is a fuel hog, but if fuel stays below $75 other factors begin to become more significant, driving the seat mile costs closer to that of a big twin. I fly for an A380 operator...passengers actively demand it over the well-appointed 747s we also fly.

Your comparison on frequency is broadly correct, but your example is based on short haul realities rather than long haul. Over great distances frequency is often once a day.

If you compared a carrier operating four 737s, you'd need to compare than to one operating three A330-200s. No prize for guessing who wins that one on passenger appeal.

Passengers in most parts of the world prefer wide bodies. Enough to overcome a slight frequency disadvantage on routes of over, say, two hours. And passenger behaviour cannot be predicted on purely rational expectations.

[LoadMan]

When I worked in research we looked at the same figures. We had pretty good and reliable data for a couple of aircraft, including very detailed OEW figures that took into account operational items and stuff.

Result was equally inconclusive. There was no appreciable weight benefit over history. We have identified the following reasons:


I know it is often said, but seats: you simply cannot find a 100% comparable layout. Using floor area as metric may make more sense, but may also not.
You never find two equal aircraft: some may have same capacity, but widely different range or field performance. A real 1-on-1 comparison is never possible. That is because aircraft are products of their time and technology, and one would be an idiot to build a 1965-aircraft in the 2000s with similar range-payload (see evolution of the B737, for example -200, -500, -600, -6MAX: all same capacity, became best sold model, second best sold model, worst sold model, discontinued model).
Modern aircraft are not lighter, but they are sometimes much more durable in terms of fatigue lifecycle. They also require less maintenance in terms of inspections.
Aircraft tend to have always a comparable relationship between empty weight and take-off weight. That is not because it is a physical law, but because only those that have are designed, built and put in service. If some technology makes something lighter, the saved weight usually re-invested (for example in more range).
Weight is no benefit in itself, it is about cost and performance. Weight may factor in airport charges, but that is about it. And you can always paper an aircraft down. Hence, aircraft are built for minimum cost and the added weight often decreases the cost of operation.


By the way: I like these threads and find them very useful. Just because the result is inconclusive doesn't mean the question and the analysis isn't justified.

[barit1]

mustangsally:
...JAL at one time had 747's flying relatively short legs, but with something around or over 500 seats. Then throw in the 380, (one of the ugliest airframes in the sky, MHO) with a couple of showers with hot running water.

JAL also had DC-10-40s dedicated to this market. It fact, they lightened the aircraft by REMOVING the center MLG, and operating at DC-10-10 max weights.

ANA jumped on the bandwagon too with their own 747SR (short range) ships about 1979. I rode a couple survey flights with them; average stage length was 45 minutes, and we had several legs loaded with 500 paying pax plus babes in arms. Wonder if the A380 has a market here?

[Gilles Hudicourt]

When new aircraft types are under development, and especially when the first production series are built, there is always ample talk about the manufacturer being able, or not, to meet expected empty weight goals. Being able to meet or failing to meet that goal affects all the rest: payload, fuel burn, range, endurance, landing and take off performance and especially the CASM.
When the manufacturer fails to meet the target Empty Weight, the ZFW is bumped to compensate and maintain the expected payload. This requires an increase in MTOW to maintain expected range. This requires more Power which increases fuel burn. The increased weights increases the take off and landing distances as well, and all this can and has, in the past, compromised certain sales.

[oceancrosser]

When I worked in research we looked at the same figures. We had pretty good and reliable data for a couple of aircraft, including very detailed OEW figures that took into account operational items and stuff.

Result was equally inconclusive. There was no appreciable weight benefit over history. We have identified the following reasons:


I know it is often said, but seats: you simply cannot find a 100% comparable layout. Using floor area as metric may make more sense, but may also not.
You never find two equal aircraft: some may have same capacity, but widely different range or field performance. A real 1-on-1 comparison is never possible. That is because aircraft are products of their time and technology, and one would be an idiot to build a 1965-aircraft in the 2000s with similar range-payload (see evolution of the B737, for example -200, -500, -600, -6MAX: all same capacity, became best sold model, second best sold model, worst sold model, discontinued model).
Modern aircraft are not lighter, but they are sometimes much more durable in terms of fatigue lifecycle. They also require less maintenance in terms of inspections.
Aircraft tend to have always a comparable relationship between empty weight and take-off weight. That is not because it is a physical law, but because only those that have are designed, built and put in service. If some technology makes something lighter, the saved weight usually re-invested (for example in more range).
Weight is no benefit in itself, it is about cost and performance. Weight may factor in airport charges, but that is about it. And you can always paper an aircraft down. Hence, aircraft are built for minimum cost and the added weight often decreases the cost of operation.


By the way: I like these threads and find them very useful. Just because the result is inconclusive doesn't mean the question and the analysis isn't justified.
You are correct on the OEW development of newer types. Look at the OEW of B737-300 - B737-700 - B737-7MAX (if not stillborn), OEW for these similar sized a/c will go from around 30t to close to 45t!

[Gilles Hudicourt]

I updated the file with a few more Boeing aircraft. Cannot find the OEW of the B787-9 or the the A350 anywhere..... They seem to be a closely guarded secret.

IF anyone has them........

https://dl.dropboxusercontent.com/u/105225711/Aircraft%20weight%20data.xlsx

[LoadMan]

The B787-9 is about 122t OEW.

[Frequent Traveller]

Hello folks ! The discussion here is driving fleet strategies and route marketing policies at airlines round the world ! Thanks Gilles !

But I recommend :
- to break aircraft types into sector type categories (RJ, feeder, VLA, WBMH, WBLH ...) and do segment analysis ... otherwise we are comparing all Y-class types with three class types or apples with bananas
- to look closely at the respective types' groundworthiness ie airport turn-around time, to compute 24h productivity : an A321 @ 218 pax turns around eg in 41' whereas its sister H21QR turns in 24'5 or 16.5' less, with 199 pax. OWE/pax are apprx. 236 kg vs 221 kg, but H21QR can take 6 AKH with payfreight on top of 4 AKH with checked-in luggage, against only 3 + 7 AKH for A321 so at the payfreight-to-pax revenue contribution conversion factor, the capacity of H21QR is 199 maindeck pax plus 6 x 10 = 60 other 'virtual' (underdeck) pax, total 259 'aggregate' pax (OWE = 181 kg/pax), which compares with 194 kg/pax for A321.

We can conclude that measured on Gilles scale - reinterpreted to include lower deck, H21QR is more efficient than A321 ... but there is a lot more to come enlargening the scope to 24h yields ... the perspective gets wider as you go through all the ingredients one by one to construct 24h-yields !

[Gilles Hudicourt]

A little context

Articles : Aircraft Interiors International (http://www.aircraftinteriorsinternational.com/articles.php?ArticleID=969)