Flight Tribhuvan International Airport departs from Kathmandu Tribhuvan International Airport at 13:10 and arrives at Singapore Changi Airport at 20:20.
The flighttime is about 5h 10m. The distance travelled ("as the bird flies"): 2030 Km. So the average speed is roughly 393 Km.
There is an 2 hour time difference between Kathmandu and Singapore