Flight Incheon International Airport departs from Seoul Incheon International Airport at 07:15 and arrives at Fukuoka Fukuoka Airport at 08:45.
The flighttime is about 1h 30m. The distance travelled ("as the bird flies"): 518 Km. So the average speed is roughly 345 Km.
The best day to arrive at Seoul is Friday and it would be best to avoid Saturday, as prices are on average 326.57% higher than on Friday. (Average prices, based on 744280 datapoints.)
We have a lot more statistics for flights LJ 261 and between Seoul and Fukuoka.
