Flight Phuket International Airport departs from Phuket Phuket International Airport at 23:25 and arrives at Seoul Incheon International Airport at 07:35.
The flighttime is about 6h 10m. The distance travelled ("as the bird flies"): 3274 Km. So the average speed is roughly 531 Km.
There is an 2 hour time difference between Phuket and Seoul
