Flight Guangzhou Baiyun International Airport departs from Guangzhou Guangzhou Baiyun International Airport at 12:40 and arrives at Seoul Incheon International Airport at 16:50.
The flighttime is about 3h 10m. The distance travelled ("as the bird flies"): 1648 Km. So the average speed is roughly 520 Km.
There is an 1 hour time difference between Guangzhou and Seoul