Flight Gimpo International Airport departs from Seoul Gimpo International Airport at 11:50 and arrives at Jeju City International Airport at 13:00.
The flighttime is about 1h 10m. The distance travelled ("as the bird flies"): 271 Km. So the average speed is roughly 232 Km.
The best day to arrive at Seoul is Tuesday and it would be best to avoid Sunday, as prices are on average 443.26% higher than on Tuesday. (Average prices, based on 693054 datapoints.)
We have a lot more statistics for flights TW 713 and between Seoul and Jeju City.
