Flight Incheon International Airport departs from Seoul Incheon International Airport at 15:00 and arrives at Tokyo Narita International Airport at 17:30.
The flighttime is about 2h 30m. The distance travelled ("as the bird flies"): 1555 Km. So the average speed is roughly 622 Km.
The best day to arrive at Seoul is Sunday and it would be best to avoid Friday, as prices are on average 227.32% higher than on Sunday. (Average prices, based on 5631255 datapoints.)
We have a lot more statistics for flights TW 215 and between Seoul and Tokyo.
THB
