Flight Hong Kong International Airport departs from Hong Kong Hong Kong International Airport at 07:55 and arrives at Siem Reap Siem Reap-Angkor International Airport at 09:30.
The flighttime is about 2h 35m. The distance travelled ("as the bird flies"): 1165 Km. So the average speed is roughly 451 Km.
There is an 1 hour time difference between Hong Kong and Siem Reap