Starting 3/9/16, Southwest Airlines will add more flights from IAD to ATL. The increase is doubled from 2x daily to 4x daily.

IAD - ATL

FLT#3089 IAD 6:55am
FLT#6037 IAD 6:45am
FLT#3551 IAD 7:45am
FLT#4513 IAD 4:15pm