fly for/tu datong

Sure, you can take the flight for the journey. Generally, it is safe enough.
The journey by train may want the visitors to view the secery along the journey and many visitors prefer that way. Another reason is that the trains are more frequent on schedule than the airs.

You can surely take the flight for Beijing around 22:30, but you'd better book a full-price or discount ticket in advance in case.

If necessary, the website may help you a lot:
https://www.travelchinaguide.com/china-flights/