Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 11:45 and arrives at Kaohsiung International Airport at 16:15.
The flighttime is about 3h 30m. The distance travelled ("as the bird flies"): 2200 Km. So the average speed is roughly 629 Km.
There is an 1 hour time difference between Bangkok and Kaohsiung