Customers of American and US Airways may have to scramble to use rewards. Ray Watson cashes in rewards right away. Benjamin Rasmussen By Miriam Cross, Associate Editor From Kiplinger's Personal Finance, March 2014 Frequent fliers on American Airlines and US Airways may be fretting about changes to their points programs once the airlines merge. The new carrier, which will fly under the American Airlines banner, won’t fully integrate for 18 months or more. On the upside, passengers can now earn and redeem miles on either airline, and eventually the ability to combine miles may bump up some travelers to elite status.See Also: Secrets to Save on Travel On the downside, US Airways customers will lose their membership in Star Alliance (the largest of the networks that let frequent fliers earn and use points traveling on affiliated foreign airlines). Those travelers should book trips on Star Alliance airlines before March 31, when memberships roll over to the smaller Oneworld program. In general, perks such as free upgrades may be harder to come by post-merger, as more elite fliers compete for fewer premium seats. Ray Watson of Southlake, Tex., is “cautiously optimistic” about the merger, he says. Still, the AA Executive Platinum member spends miles as he acquires them (on an upcoming first-class family trip to Japan, for example). That’s a good strategy regardless of which airline you favor. Delta, United and Southwest are all devaluing miles in 2014, and more likely than not, the new American will follow suit.