The pilot reported landing gear problems after taking off bound for Chicago on Wednesday morning.
The plane did a fly-by to give ground crews a chance to examine the exteriors of the plane before it landed.
Southwest Flight 2547 took off from Oakland at 6:13 a.m. local time heading for Chicago Midway, but had to turn around.
In an email to our sister KGO, Southwest says: "Flight 2547 departed Oakland for Chicago Midway with 139 passengers onboard. After takeoff, the Captain in Command made the decision to return to Oakland to check a maintenance item on the aircraft. With everything we do, safety is of paramount importance and we appreciate our customers' patience while we work to get them to their final destinations for the holiday."
Landing gear issue on Southwest flight from Oakland to Chicago . Returning now, see it circling on flight aware. pic.twitter.com/sALAtjSd6V— Reggie Aqui (@reggieaqui) December 23, 2015