Flight Hartsfield Jackson International Airport departs from Atlanta Hartsfield Jackson International Airport at 12:00 and arrives at Houston George Bush Intercontinental Airport at 13:14.
The flighttime is about 2h 14m. The distance travelled ("as the bird flies"): 1213 Km. So the average speed is roughly 543 Km.
There is an 1 hour time difference between Atlanta and Houston