Flight Hong Kong International Airport departs from Hong Kong Hong Kong International Airport at 01:40 and arrives at Singapore Changi Airport at 05:30.
The flighttime is about 3h 50m. The distance travelled ("as the bird flies"): 1322 Km. So the average speed is roughly 345 Km.
The best day to arrive at Hong Kong is Wednesday and it would be best to avoid Sunday, as prices are on average 298.4% higher than on Wednesday. (Average prices, based on 2008399 datapoints.)
We have a lot more statistics for flights OM 5613 and between Hong Kong and Singapore.