Flight Hong Kong International Airport departs from Hong Kong Hong Kong International Airport at 11:15 and arrives at Singapore Changi Airport at 15:05.
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 Thursday and it would be best to avoid Wednesday, as prices are on average 114.2% higher than on Thursday. (Average prices, based on 2013259 datapoints.)
We have a lot more statistics for flights CX 739 and between Hong Kong and Singapore.