Flight Gimpo International Airport departs from Seoul Gimpo International Airport at 15:45 and arrives at Tokyo Haneda Airport at 17:50.
The flighttime is about 2h 05m. The distance travelled ("as the bird flies"): 1450 Km. So the average speed is roughly 696 Km.
The best day to arrive at Seoul is Sunday and it would be best to avoid Thursday, as prices are on average 43.8% higher than on Sunday. (Average prices, based on 1558011 datapoints.)
We have a lot more statistics for flights OZ 1045 and between Seoul and Tokyo.
