Flight Daxing International Airport departs from Beijing Daxing International Airport at 15:00 and arrives at Chengdu Chengdu Shuangliu International Airport at 18:15.
The flighttime is about 4h 15m. The distance travelled ("as the bird flies"): 1424 Km. So the average speed is roughly 335 Km.
There is an 1 hour time difference between Beijing and Chengdu