Flight Hong Kong International Airport departs from Hong Kong Hong Kong International Airport at 16:45 and arrives at Chiang Mai Chiang Mai International Airport at 18:50.
The flighttime is about 3h 05m. The distance travelled ("as the bird flies"): 1665 Km. So the average speed is roughly 540 Km.
There is an 1 hour time difference between Hong Kong and Chiang Mai