Flight Incheon International Airport departs from Seoul Incheon International Airport at 20:40 and arrives at Hong Kong Hong Kong International Airport at 23:45.
The flighttime is about 4h 05m. The distance travelled ("as the bird flies"): 1621 Km. So the average speed is roughly 397 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 67.61% higher than on Wednesday. (Average prices, based on 21461259 datapoints.)
We have a lot more statistics for flights HX 623 and between Seoul and Hong Kong.
