Flight Changi Airport departs from Singapore Changi Airport at 02:00 and arrives at Seoul Incheon International Airport at 09:15.
The flighttime is about 6h 15m. The distance travelled ("as the bird flies"): 2923 Km. So the average speed is roughly 468 Km.
There is an 1 hour time difference between Singapore and Seoul
The best day to arrive at Singapore is Monday and it would be best to avoid Saturday, as prices are on average 125.94% higher than on Monday. (Average prices, based on 426125 datapoints.)
We have a lot more statistics for flights TR 842 and between Singapore and Seoul.