Flight Incheon International Airport departs from Seoul Incheon International Airport at 19:00 and arrives at Singapore Changi Airport at 00:45.
The flighttime is about 6h 45m. The distance travelled ("as the bird flies"): 2923 Km. So the average speed is roughly 433 Km.
There is an 1 hour time difference between Seoul and Singapore
The best day to arrive at Seoul is Thursday and it would be best to avoid Monday, as prices are on average 436.95% higher than on Thursday. (Average prices, based on 266214 datapoints.)
We have a lot more statistics for flights TW 171 and between Seoul and Singapore.