A labor dispute at America’s third busiest airport is promising to turn what is already a bad travel day into a nightmare.

One of the nation’s biggest unions plans to effectively block two entrances into Los Angles International airport, a protest police fear will turn the streets outside into a parking lot at a time when tens of thousands of cars are pouring into the airport.

The Service Employees International Union, or SEIU, claims a company that employs 450 sky caps, cabin cleaners and security workers at LAX illegally broke a contract and is in violation of the city’s living wage ordinance.

That company, Aviation Safeguards, claims that’s inaccurate, saying 52 percent of its workers voted to decertify the SEIU. It also says employee pay has increased by more than $2 million since workers kicked the union out to compensate for changes in their health care policies.