Flight International Airport departs from Muscat International Airport at 09:00 and arrives at Colombo Bandaranaike International Airport at 14:40.
The flighttime is about 4h 10m. The distance travelled ("as the bird flies"): 2466 Km. So the average speed is roughly 592 Km.
There is an 1.5 hour time difference between Muscat and Colombo