The 49-year-old handbag designer was witnessed being dropped off at the airport and entering the terminal with coffee and luggage in hand.
The former couple share three children together, Cayden 16, Hayes, 14, and Grace, 13. (Costner also has four adult children from previous relationships.)
The trip isn’t expected to be a long one, according to the outlet, as Baumgartner is due back in court in Santa Barbara on Wednesday for a hearing about the prenuptial agreement in the split.
Baumgartner and her kids toted backpacks and luggage as they exited a vehicle and were seen making their way toward the terminal on the summer day.
Baumgartner wore a floral pattern shirt with black flare pants and sandals on the summer day. Hayes and Grace matched in long-sleeved gray tops with plaid pants ahead of the plane ride.
Costner has claimed the $248,000 a month in child support his estranged wife is demanding is partly to fund her own plastic surgery expenses.
Baumgartner – who reportedly ‘blindsided’ Costner, 68, when she handed him divorce papers – called the requested amount ‘less than the amount needed to maintain the children in their accustomed lifestyle,’ reported People Magazine earlier this month.