Flight Incheon International Airport departs from Seoul Incheon International Airport at 11:10 and arrives at Bangkok Suvarnabhumi Airport at 20:35.The flight has a short stop at Hong Kong.
The flighttime is about 11h 25m. The distance travelled ("as the bird flies"): 2992 Km. So the average speed is roughly 262 Km.
There is an 2 hour time difference between Seoul and Bangkok