Flight Cam Ranh International Airport departs from Nha Trang Cam Ranh International Airport at 01:50 and arrives at Seoul Incheon International Airport at 08:40.
The flighttime is about 4h 50m. The distance travelled ("as the bird flies"): 2289 Km. So the average speed is roughly 474 Km.
There is an 2 hour time difference between Nha Trang and Seoul