AirTran Airways pilots have begun their transition to becoming Southwest Airlines pilots.

The move for pilots comes as the airline prepares to unveil its first AirTran plane newly painted in Southwest colors -- a milestone expected in April. Pilots are gradually shifting over to Southwest as the planes are converted over the next couple of years.

Dallas-based Southwest acquired Orlando-based AirTran last year, a deal that opened the door for Southwest to begin flying to Atlanta where AirTran has operated its largest hub. Southwest launched its service at Hartsfield-Jackson International Airport last month, though AirTran will continue flying for a couple of years.

The first class of 24 AirTran pilots begin training Wednesday at Southwest's headquarters in Dallas.

The pilots are the third group to go from AirTran to Southwest. A group of corporate employees shifted over in January, followed by some non-union maintenance and engineering employees last week.