Flight Narita International Airport departs from Tokyo Narita International Airport at 09:00 and arrives at Da Nang Da Nang International Airport at 13:15.
The flighttime is about 6h 15m. The distance travelled ("as the bird flies"): 3744 Km. So the average speed is roughly 599 Km.
There is an 2 hour time difference between Tokyo and Da Nang
