Originally Posted by
Finite Elephant
South Korea has normalized relations with China and KE and OZ fly to several Chinese cities, so I can't imagine flying over China is a big deal. Same with Russia.
With regard to China, I once flew on CX, a China (Hong Kong SAR) based airline, from HKG to SFO. The flight path taken avoided flying over any land in China other than the Hong Kong SAR, even though this lengthened the route. Interestingly enough, the flight path went directly over Taiwan.
In other words, there may be other reasons why an airline might (sometimes) be unable to fly over China.