Members of the Transport Workers Union also plan pickets at airports in Baltimore, Pittsburgh and Seattle. The union represents 7,200 ramp, operations, provisioning and freight agents.

The union says some of its members haven’t had a raise since 2005. Contract negotiations began in January but broke down in October.

Union negotiating committee member Patti Adams says the airline and union will meet with a federal mediator on Monday.

Southwest’s Whitney Eichinger says the airline is working to resolve the remaining contract issues. The picketers are on their off time and no flight delays are expected.

The agreement, which the Dallas-based airline said was “cost neutral,” must be approved by members of the Aircraft Mechanics Fraternal Organization. If approved, it will last four years.

Union officials said the deal would provide industry-leading compensation for mechanics, as well as improvements in productivity and efficiency.

It will also provide additional job security for mechanics.

According to a statement from the union, the deal includes “a very limited opportunity for Southwest Airlines to seek an international outsourcing maintenance provider if the need arises.”

Southwest had planned to outsource some maintenance to a firm based in El Salvador. But it abandoned those plans earlier this year after its maintenance program came under fire from the Federal Aviation Administration for alleged lapses in inspections.

Southwest is also negotiating contracts with pilots and ground workers. Union officials representing pilots and flight attendants have criticized the airline’s plan to partner with Canadian and Mexican airlines for international flights. Labor leaders say they would prefer Southwest operate those flights.