Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 13:55 and arrives at Haikou Haikou Meilan International Airport at 17:10.
The flighttime is about 2h 15m. The distance travelled ("as the bird flies"): 1094 Km. So the average speed is roughly 486 Km.
There is an 1 hour time difference between Bangkok and Haikou