That's not even that high.
You want high and constant costs!?
Try the North American and Asian carriers flying transpolar from Canadian airspace to Russian airspace to the Middle East/South Asia and mostly East Asia.
crossing more than 80*N EVERY DAY
Essentially the Americans, Canadians, Russian, Japanese, Chinese and Europeans figured out that flying higher saves more fuel but the airspace cost is $$$ over the Russian airspace (they make profit on this $$$) but I hear it may be reduced due to recent trans-polar meetings with all the parties and system upgrades on the Russian side (Specifically Nov. 17 RVSM in Russia & Central Asia).
Once RVSM is implemented I believe there will be more efficient routing from East/South Asia to Europe via Russia/Central Asia.
, circa trans-polar NRT
The 777 does it every-day and is built for it.