Flight Incheon International Airport departs from Seoul Incheon International Airport at 14:45 and arrives at Hong Kong Hong Kong International Airport at 17:35.
The flighttime is about 3h 50m. The distance travelled ("as the bird flies"): 1621 Km. So the average speed is roughly 423 Km.
There is an 1 hour time difference between Seoul and Hong Kong
The best day to arrive at Seoul is Saturday and it would be best to avoid Sunday, as prices are on average 162.35% higher than on Saturday. (Average prices, based on 18792427 datapoints.)
We have a lot more statistics for flights HX 629 and between Seoul and Hong Kong.