Flight Gimpo International Airport departs from Seoul Gimpo International Airport at 08:55 and arrives at Jeju City International Airport at 10:10.
The flighttime is about 1h 15m. The distance travelled ("as the bird flies"): 271 Km. So the average speed is roughly 217 Km.
The best day to arrive at Seoul is Monday and it would be best to avoid Sunday, as prices are on average 274.72% higher than on Monday. (Average prices, based on 815054 datapoints.)
We have a lot more statistics for flights KE 1049 and between Seoul and Jeju City.