The merger between US Airways and American is official, but don't expect to see any big changes anytime soon.

Bob Ciminelli, US Air's vice president for the Philly hub says the changes will develop slowly.

"Immediately, nothing, it will be business as usual," said Ciminelli. "Customers flying on American will have to go to the American ticket counter and gates, same for our US Airways customers. It will be take us between 18 to 24 months to get us all to one airline."

The first change Ciminelli says will happen early in 2014 when the two frequent flyer programs will be combined.

"Our customers need not worry about their miles, they are safe. We'll have a process to earn and redeem on each other's carrier. Long term there will be a single loyalty program. We'll also in January announce a code share where customers can book flights on each other," he said.

 The complete rebranding will take up to two years and officials say will not mean any loss of service at Philadelphia's airport.