Flight Incheon International Airport departs from Seoul Incheon International Airport at 09:00 and arrives at Hong Kong Hong Kong International Airport at 11:40.
The flighttime is about 3h 40m. The distance travelled ("as the bird flies"): 1621 Km. So the average speed is roughly 442 Km.
There is an 1 hour time difference between Seoul and Hong Kong
The best day to arrive at Seoul is Wednesday and it would be best to avoid Saturday, as prices are on average 48.39% higher than on Wednesday. (Average prices, based on 18009280 datapoints.)
We have a lot more statistics for flights OZ 721 and between Seoul and Hong Kong.