Flight Cam Ranh International Airport departs from Nha Trang Cam Ranh International Airport at 00:35 and arrives at Seoul Incheon International Airport at 07:35.
The flighttime is about 5h 00m. The distance travelled ("as the bird flies"): 2289 Km. So the average speed is roughly 458 Km.
There is an 2 hour time difference between Nha Trang and Seoul