Flight Incheon International Airport departs from Seoul Incheon International Airport at 16:45 and arrives at Singapore Changi Airport at 22:20.
The flighttime is about 6h 35m. The distance travelled ("as the bird flies"): 2923 Km. So the average speed is roughly 444 Km.
There is an 1 hour time difference between Seoul and Singapore
The best day to arrive at Seoul is Saturday and it would be best to avoid Thursday, as prices are on average 270.34% higher than on Saturday. (Average prices, based on 690581 datapoints.)
We have a lot more statistics for flights OZ 6789 and between Seoul and Singapore.