Flight Tribhuvan International Airport departs from Kathmandu Tribhuvan International Airport at 09:50 and arrives at Muscat International Airport at 12:55.
The flighttime is about 5h 05m. The distance travelled ("as the bird flies"): 3012 Km. So the average speed is roughly 593 Km.
There is an 2 hour time difference between Kathmandu and Muscat