American Airlines and US Airways have been rumored to be merging longer than Brett Favre contemplated retirement.

The rumors are still out there. American Airlines flight attendants, who just ratified a contract, have publicly affirmed their support for such a merger.

Will it happen? Maybe. But it might not be too soon for travelers to start thinking about how it might affect them, and to plan accordingly.

To be fair, any merger would probably take over a year to happen, especially with all the approvals that would be involved; the new airline would be one of the country’s largest and antitrust studies will be extensive. So, changes won’t happen overnight. But there will be some changes passengers should watch for.

An early change would almost certainly be US Airways leaving the Star Alliance mileage program and joining American’s AAdvantage program.

As far as mileage redemption, US Airways does not have that many prime destinations that other Star Alliance carriers do not serve. They do, however, have a strong Caribbean presence that United and Continental lack and more flights throughout the southern U.S.

Thus, even travelers who haven’t redeemed awards with US Airways often use the carrier to earn United miles, miles that count towards elite status.

In addition, perhaps because they have few nonstop cross-country flights, except to and from Philadelphia, US Airways often has inexpensive fares, especially at the last minute, and those may well disappear as part of an American/US Airways merger.

US Airways also often sells international discount fares through consolidators in both coach and business class, which American also is less likely to continue on their routes.

There’s also the hub issue. US Airways now has hubs at Phoenix, Charlotte and Philadelphia. As travelers in places like St. Louis and Cincinnati know, airline mergers are not kind to lesser hubs. Most of TWA’s St. Louis flights have disappeared since American took over, along with many of Delta’s flights from Cincinnati, now that Delta has merged with Northwest. What might happen to US Airways’ hubs. Will they all survive?

Again, at this point, the merger talk is just talk, and nothing in the airline industry moves quickly. But, my suggestion for anyone planning travel with US Airways using miles is to book as soon as possible.

If you have an award ticket booked with US Airways on a partner carrier, it will remain valid. If it’s on US Airways and the carrier drops a route, American should honor the ticket.

Also, a merger may well create a run on award tickets, especially if there is a deadline for travel under the old system, and especially to destinations that Oneworld carriers don’t serve as well as Star Alliance.

For example, US Airways partner United has a lot more flights to Hawaii than American. On the other hand, American has much better service to the Caribbean.

Finally, airfares usually don’t go up immediately upon a merger announcement, but pay attention to any proposed official date. When United merged with Continental, fares to Newark, for example, stayed low until the Continental name disappeared, then in some cases airfares (San Francisco and Los Angeles to Newark, for example) almost doubled overnight.

There will no doubt be other changes if this merger happens, especially to inflight entertainment and service. Plus, passengers and frequent fliers will be inundated with joint announcements that the new airline will be a boon to consumers. Don’t bet on the last one.