DALLAS - American Airlines and Tempe-based US Airways will merge and create the world's biggest airline. The boards of both companies approved the merger late Wednesday, according to four people close to the situation.

The carrier keeps the American Airlines name but will be run by US Airways CEO Doug Parker. American's CEO, Tom Horton, will become chairman of the new company, these people said. They requested anonymity because the merger negotiations were private.

A formal announcement is expected this morning.

If approved by a U.S. Bankruptcy Court judge and by regulators, the $11 billion all-stock deal will forge a financially stronger airline, but move one of Arizona's six Fortune 500 companies to Fort Worth, Texas, The Arizona Republic reported.

The deal has been in the works since August, when creditors forced American to consider a merger rather than remain independent. American has been restructuring under bankruptcy protection since late 2011.

Together, American and US Airways will be slightly bigger than United Airlines. Travelers won't notice immediate changes. It will likely be months before the frequent-flier programs are merged, and possibly years before the airlines are fully combined.

US Airways executives have said they intend to maintain Phoenix Sky Harbor International Airport as a hub for the merged airline, The Republic reported.