PHILADELPHIA - The planned merger of US Airways and American Airlines could have big implications for Philadelphia International Airport.

Philadelphia is a hub for US Airways, which announced Thursday that it would merge with American to form the world's largest airline.

US Airways CEO Doug Parker says the combined carrier will keep all eight of its hubs. But past airline mergers suggest that's unlikely in the long run.

Mayor Michael Nutter said Thursday that the merger could bring more international flights to the city and create more jobs at the airport.

Meanwhile, frequent flyers say they're concerned about keeping their preferred status, which allows them to upgrade their seats and board early.

The merger must still be approved by antitrust regulators.