As we all know, the flight information region in China uses the metric altitude layer. However, when you use A1, L642, M771, and N892 to cross the Sanya Flight Information Region, you can still continue to use feet level altitude without changing.
The area where the above-mentioned route is located is called the “Sanya Oceanic Airspace” (referring to the part of the Sanya FIR south of Hainan Island).
If your route often requires crossing the Sanya FIR and you are a player who pursues authenticity, I suggest using the Sanya Oceanic airspace route during your flight, which will bring you a more realistic and convenient flying experience.
