As to China, Hong Kong has RNP AR procedures. So, at least that portion of China is WGS84 compliant. So is Tibet as it has a very sophisticated RNP AR approach procedure developed some years ago for China Airlines by Naverous.
Yes, I can confirm that the procedures for China use WGS84. The terrain model is WGS84 and based on SRTM data. Getting a survey on local terrain/vegetation, controlling obstacles, and the airport data was all created from scratch.
Yes India24, the UTM was comment rushed, I was thinking about the current project I am working on where the land based mapping is UTM.
WGS 84 is based on the prime meridian. A straight path across the surface is one thing to calculate, but a curve path on the surface is quite the other...the regulatory agencies were using the Helmert Formula, but that is not accurate enough for curves, so we use Vincenty's Formula which is far better.
In the end, the aircraft system understands WGS 84...
From Jeppeson. WGS84 Compliance worldwide...
http://ww1.jeppesen.com/company/publications/wgs-84.jsp