|Quoting AirbusDriver (Reply 60):|
To put this myth to rest forever, here is the fuel burn according to Boeing and Airbus. ( Data available on A and B Web site )
A340-300 Seat 295 Max range 7400NM with 39060 GAL or 4.18 Gal per N/M
B772-ER Seat 301 Max range 7730NM with 45220 Gal or 5.84 Gal per N/M
A340-500 Seat 313 Max Range 9000NM with 56750 Gal or 6.30 Gal per N/M
B772-LR Seat 301 Max Range 9420NM with 53440 Gal or 5.67 Gal per N/M
A340-600 Seat 380 Max Range 7900NM with 51746 Gal or 6.55 Gal per N/M
B773-ER Seat 365 Max range 7880NM with 47890 Gal or 6.07 Gal per N/M
This is absolutely not fuel burn data...
You simply used maximum fuel tankage divided by design range...this is meaningless as with the exception 777-300ER and -200LR none of these aircraft can carry maximum fuel with design payload...and even then the loaded fuel is not indicative of fuel burned. As a pilot I would have thought this would be immediately evident to you...
The information I've posted in this regard is quite extensive. Here is some data relevant to this post:
300-400 Seat Design Range/Payload Comparison
Some calculated data:
300-400 Seat Specific Fuel Burn Comparison
The burn per seat data puts things in a better perspective relative to the head to head performance comparison especially when comparing a340-500 to the 777-200LR. If you bring the range down to match the A345 takeoff weight reduces dramatically and that reduction is all fuel. For the 777-200LR vs A340-500 highest gross weight at design payload and 9,000nm range the burn difference is >20%...
Equal Mission Distance With Design Payload 777-200LR/A340-500
Fuel specifics come out like this:
Equal Mission Distance Specific Fuel Burn 777-200LR/A340-500
*Burn figures are to +/- 1,000lbs for calculated sector lengths.
*Standard cruise profiles according to brake release weight
|Quoting Ikramerica (Reply 59):|
777 has lower fuel burn, higher dispatch reliability, better payload and lower maintenance costs. It's not just 5-10% fuel burn, and it's why the sales of 340s declined as the sales of 777s increased, and then after the blip of the 345/346 being the only planes in the market of that size, the 777LR program again sent the 340 into retirement. It's not rumor, it's not wishful thinking, it's the reality.
|Quoting Trex8 (Reply 56):|
I'm not trying to put down the A340, I was trying to rationalize why some operators will still prefer the A340 even if there are other suitable alternatives , like a A333 which burns about 10% less fuel than a A343 over comparable length sectors - see the SAS emissions site. As for what a 777 might do compared to an A340, I have seen numbers anywhere from 5% (at least for a A346 vs 77W comparison per wbp's posts here) to claims of over 20% (which I seriously doubt).
You are both right and also missing something...
The payload specific advantage over the A340-600 is about 12% in terms of fuel burn per unit payload. However when factoring in more effective aircraft payload utilization that figure can rise an additional 3-5% on sector lengths of 6,000-7,000nm. The 777-300ER can carry heavier payloads a bit farther while burning less fuel...I would not be surprised at all if the 777-300ER gets close to 20% better fuel burn per sector if you factor in increased useable volume in the lower hold as an offset to fuel burn...
|Quoting Johnny (Reply 57):|
On ETOPS-Critical Sectors which result in longer routings for the B777 this figure changes to 4-5 percent.
What specific sectors are you referring to that are being operated today by 777's and any other four engined aircraft where ETOPS routing changes the 777's sector distance, time or fuel burn by 5%??? Maybe that was the case some years ago, Kamchatka overflight comes to mind, but it's not so today. Even flights in the vicinity of the Himalayas to Europe with 777-300ER's only take nominally 10-15min longer than 747's. But that's not due to routing but to the slower flight speed of the 777...
Newly approved routes and more highly capable ETOPS aircraft have all but eliminated any significant detriment to ETOPS sector planning in the Northern Hemisphere. Operators who have invested in ETOPS infrastructure have benefited greatly and will continue to do so. The only big problem for ETOPS operation arises if you don't do what you need to do to maintain the maintenance standard...some carriers have learned that the hard way...