Flight Tribhuvan International Airport departs from Kathmandu Tribhuvan International Airport at 23:10 and arrives at Singapore Changi Airport at 06:30.
The flighttime is about 5h 20m. The distance travelled ("as the bird flies"): 2030 Km. So the average speed is roughly 381 Km.
There is an 2 hour time difference between Kathmandu and Singapore