Ever since American Airlines merged with US Airways, a new chapter is set to open. The effect of the merger would be most on frequent fliers. In a significant step indicating a new beginning, American Airlines Group has decided to leave Star Alliance and join Oneworld.

Star Alliance and Oneworld are two leading global airlines alliance with leading international airlines as their partner members.
 
With the new Oneworld membership, US Airways frequent fliers would now be eligible to earn and redeem miles on a new set of airlines. Currently, there are 16 member airlines in Oneworld. These include American Airlines, Cathay Pacific Airways, Japan Airlines, British Airways and Qatar Airways.
The latest to join Oneworld is Qatar Airways. The airline became member in October 2013. Qatar Airways is to begin daily nonstop flights between Doha and Philadelphia starting from April 2, 2014. The airline will provide connectivity to 136 destinations in the Middle East, South America, Asia, Africa and India.

Despite the shifting of allegiance to Oneworld, US Airways will continue to retain codeshare partnership with 12 airlines that are currently not part of Oneworld. With the new Oneworld membership, the airline plans to phase out codeshare pact with these airlines in coming months. However, US Airways frequent fliers would continue to redeem and earn miles with these carriers as of now.

US Airways frequent fliers would not be able to earn or redeem miles on majority of 28 partner airlines of Star Alliance, including Swiss International Air Lines, Asiana Airlines and Lufthansa. The flights booked with erstwhile Star Alliance partners by US Airways frequent fliers are safe, but miles would not be able to be earned or redeemed for these flights.