Flight Huanghua International Airport departs from Changsha Huanghua International Airport at 23:25 and arrives at Bangkok Don Mueang International Airport at 01:40.
The flighttime is about 3h 15m. The distance travelled ("as the bird flies"): 1466 Km. So the average speed is roughly 451 Km.
There is an 1 hour time difference between Changsha and Bangkok