Flight Haneda Airport departs from Tokyo Haneda Airport at 15:40 and arrives at Seoul Gimpo International Airport at 18:00.
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 Tokyo is Tuesday and it would be best to avoid Saturday, as prices are on average 123.36% higher than on Tuesday. (Average prices, based on 392428 datapoints.)
We have a lot more statistics for flights JL 93 and between Tokyo and Seoul.
THB
