Flight Hong Kong International Airport departs from Hong Kong Hong Kong International Airport at 19:15 and arrives at Kathmandu Tribhuvan International Airport at 22:00.
The flighttime is about 4h 45m. The distance travelled ("as the bird flies"): 3173 Km. So the average speed is roughly 668 Km.
There is an 2 hour time difference between Hong Kong and Kathmandu