Flight Gimpo International Airport departs from Seoul Gimpo International Airport at 19:55 and arrives at Tokyo Haneda Airport at 22:15.
The flighttime is about 2h 20m. The distance travelled ("as the bird flies"): 1450 Km. So the average speed is roughly 621 Km.
The best day to arrive at Seoul is Tuesday and it would be best to avoid Thursday, as prices are on average 18.28% higher than on Tuesday. (Average prices, based on 1084133 datapoints.)
We have a lot more statistics for flights NH 868 and between Seoul and Tokyo.
INR
