Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 11:05 and arrives at Haikou Haikou Meilan International Airport at 14:30.
The flighttime is about 2h 25m. The distance travelled ("as the bird flies"): 1094 Km. So the average speed is roughly 453 Km.
There is an 1 hour time difference between Bangkok and Haikou