Flight Cam Ranh International Airport departs from Nha Trang Cam Ranh International Airport at 01:35 and arrives at Seoul Incheon International Airport at 07:55.
The flighttime is about 4h 20m. The distance travelled ("as the bird flies"): 2289 Km. So the average speed is roughly 528 Km.
There is an 2 hour time difference between Nha Trang and Seoul