Originally Posted by
seenitall
I very much doubt that it would be efficient for it to have 763ER range. The goal is to fly 4000 nm economically -- because that would cover most TATL routes. If you heavy-up the plane to carry enough fuel to fly 5500 nm, you kill the economics.
It's never most efficient to fly a plane at 100% of its range because it needs more fuel to fly farther, which means more weight, which means more fuel, etc. Every plane has a "tipping point" where a plane goes from burning less fuel per extra nmi to burning more fuel per extra nmi. A 77W has this point around 3,000 nmi and a 772 has it around 2,500 nmi. Obviously, airlines fly many routes at different ranges with these aircraft, but just something to consider.
For a plane designed to fly routes of ~4000 nmi, I think it would have a range of 5000 nmi. This will prevent it from ever making TATL fuel stops like the 752 occasionally has to do, and allow it to cover all of Europe. This allows Boeing to market not just to UA and DL for TATL routes from NYC, but also smaller airlines in Europe like A3, RO, and OK. The range would also enable DL/UA to expand into smaller cities in Japan from SEA/SFO. SA is also rumored to be replacing their fleet the 797 would be a major upgrade there as well.