Britney Spears is back in the Pacific Time Zone.

The popster touched down Monday night at Bob Hope Airport in Burbank after a long weekend of fun in the sun at Mel Gibson's beachside digs in northern Costa Rica.

Sources close to Spears tell E! News the rested mother of two had to be back in Los Angeles early this week to prep for a meeting with Kevin Federline to work on an even more evolved custody arrangement. Both sides' attorneys will be present, and the heat is on—L.A. Superior Court Commissioner Scott Gordon has said he will set a trial date in August or September if they can't move forward on their own.

Meanwhile, it's unclear whether Jamie Spears was on his daughter's private flight back to the States, but we do know her William Morris agent—and designated ATV driver—Jason Trawick was along for the ride.

And still might be...