Flight Changi Airport departs from Singapore Changi Airport at 12:55 and arrives at Hong Kong Hong Kong International Airport at 17:15.
The flighttime is about 4h 20m. The distance travelled ("as the bird flies"): 1322 Km. So the average speed is roughly 305 Km.
The best day to arrive at Singapore is Tuesday and it would be best to avoid Friday, as prices are on average 106.92% higher than on Tuesday. (Average prices, based on 3504780 datapoints.)
We have a lot more statistics for flights CX 690 and between Singapore and Hong Kong.
