Flight Hong Kong International Airport departs from Hong Kong Hong Kong International Airport at 19:00 and arrives at Kathmandu Tribhuvan International Airport at 22:10.
The flighttime is about 5h 10m. The distance travelled ("as the bird flies"): 3173 Km. So the average speed is roughly 614 Km.
There is an 2 hour time difference between Hong Kong and Kathmandu