US Airways and United Airlines announced a marketing partnership Wednesday that would allow the airlines to sell tickets on each other's flights.
Also, United and US Airways customers would be able to earn and redeem frequent flyer miles on either airline and use both carriers' airport clubs.
The code-sharing agreement is a major part of a restructuring plan US Airways is implementing to avoid bankruptcy.
"A marketing agreement should significantly boost our revenues by giving us reach to more markets and enabling us to offer our customers more choices and greater convenience," US Airways chief executive David Siegel said.
US Airways has long sought such a partnership with an airline that would feed customers into its strong route system up and down the East Coast. With mostly transcontinental, Western and international routes, United is a good fit.
US Airways is the third-largest carrier at Tampa International Airport, where United has a small presence.
The deal will give US Airways customers better connections and more destinations on United's global network, said Louis Miller, the airport's executive director. It also will shore up the only two major carriers asking for government loan guarantees.
"It gives US Airways customers more choices," Miller said. "And it should strengthen two airlines that are in trouble financially. I can't see any downside."
The two airlines had tried to merge last year, but federal regulators rejected the deal, citing competitive concerns. United had planned to pay $60 a share to purchase US Airways before the deal was rejected.
Since then, US Airways' stock has plummeted in the aftermath of the Sept. 11 attacks and its subsequent damage to the airline industry. US Airways shares closed Wednesday at $2.51 a share, up 36 cents.
UAL Corp., parent of United, closed at $4.70 a share, down 70 cents, or 13 percent.
The agreement was announced after markets closed. Despite the partnership and recent cost-cutting deals with its pilots and flight attendants, US Airways has warned that bankruptcy is still a possibility.
_ Times staff writer Steve Huettel contributed to this report.