Flight Incheon International Airport departs from Seoul Incheon International Airport at 20:15 and arrives at Nanjing Lukou Airport at 21:45.
The flighttime is about 2h 30m. The distance travelled ("as the bird flies"): 910 Km. So the average speed is roughly 364 Km.
There is an 1 hour time difference between Seoul and Nanjing
