Flight Changi Airport departs from Singapore Changi Airport at 06:25 and arrives at Hong Kong Hong Kong International Airport at 10:20.
The flighttime is about 3h 55m. The distance travelled ("as the bird flies"): 1322 Km. So the average speed is roughly 338 Km.
The best day to arrive at Singapore is Tuesday and it would be best to avoid Saturday, as prices are on average 42.17% higher than on Tuesday. (Average prices, based on 2226787 datapoints.)
We have a lot more statistics for flights TR 978 and between Singapore and Hong Kong.