Flight Indira Gandhi International Airport departs from Delhi Indira Gandhi International Airport at 04:40 and arrives at Kathmandu Tribhuvan International Airport at 06:35.
The flighttime is about 1h 25m. The distance travelled ("as the bird flies"): 917 Km. So the average speed is roughly 647 Km.
There is an 0.5 hour time difference between Delhi and Kathmandu