Flight Hong Kong International Airport departs from Hong Kong Hong Kong International Airport at 15:15 and arrives at Singapore Changi Airport at 19:10.
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 Hong Kong is Friday and it would be best to avoid Sunday, as prices are on average 67.2% higher than on Friday. (Average prices, based on 2040489 datapoints.)
This graph shows the distribution of prices found in the past years for this flight. (Average prices, based on 150 datapoints.)
We have a lot more statistics for flights CX 635 and between Hong Kong and Singapore.