Flight Narita International Airport departs from Tokyo Narita International Airport at 13:25 and arrives at Seoul Incheon International Airport at 15:45.
The flighttime is about 2h 20m. The distance travelled ("as the bird flies"): 1555 Km. So the average speed is roughly 666 Km.
The best day to arrive at Tokyo is Thursday and it would be best to avoid Sunday, as prices are on average 427.63% higher than on Thursday. (Average prices, based on 3874597 datapoints.)
We have a lot more statistics for flights LJ 206 and between Tokyo and Seoul.
THB
