Flight Istanbul Atatürk Airport departs from Istanbul Istanbul Atatürk Airport at 20:15 and arrives at Kathmandu Tribhuvan International Airport at 06:05.
The flighttime is about 6h 50m. The distance travelled ("as the bird flies"): 6302 Km. So the average speed is roughly 922 Km.
There is an 3 hour time difference between Istanbul and Kathmandu