Flight Tribhuvan International Airport departs from Kathmandu Tribhuvan International Airport at 14:30 and arrives at Kolkata Netaji Subhas Chandra Bose International Airport at 16:00.
The flighttime is about 2h 00m. The distance travelled ("as the bird flies"): 344 Km. So the average speed is roughly 172 Km.
There is an 0.5 hour time difference between Kathmandu and Kolkata