Aha, found it by accident whilst searching for something else. 1500-2000nm.
https://www.sciencedirect.com/science/a ... 2314001793You can't see the detailed data from that - it's buried behind a paywall, but I got it through our university library.
kg of fuel per seat-nautical mile...
500-1000nm sectors, 0.049
1000-1500nm sectors, 0.041
1500-2000nm sectors, 0.039
2000-2500nm sectors, 0.042
2500-3000nm sectors, 0.047
3000-3500nm sectors, 0.048
3500-4000nm sectors, 0.048
4000-4500nm sectors, 0.050
4500-5000nm sectors, 0.051
5000-5500nm sectors, 0.052
5500-6000nm sectors, 0.059
6000-6500nm sectors, 0.067
So, per seat mile, between 2000 and 6500nm, roughly speaking you're pushing the carbon footprint up by about 37%. I'd guess the long A350 legs talked about here, nearer 100%, but I was always taught to extrapolate off the end of graphs at your peril!
G
I am Spartacus, and so is my co-pilot.