Flight Incheon International Airport departs from Seoul Incheon International Airport at 10:40 and arrives at Beijing Beijing Capital International Airport at 12:05.
The flighttime is about 2h 25m. The distance travelled ("as the bird flies"): 1106 Km. So the average speed is roughly 458 Km.
There is an 1 hour time difference between Seoul and Beijing
The best day to arrive at Seoul is Monday and it would be best to avoid Sunday, as prices are on average 238.99% higher than on Monday. (Average prices, based on 44035 datapoints.)
We have a lot more statistics for flights KE 855 and between Seoul and Beijing.