If you are like most flyers, then much of your airline patronage will occur with American Airlines, Delta Air Lines, United Airlines, and Southwest Airlines. It so happens that these carriers are the four largest airlines in the world, in order of passengers carried. You should have a frequent-flyer account for each of these airlines. You will have the three alliances covered in addition to the valuable Rapid Rewards program of Southwest Airlines.
|Delta Air Lines||SkyMiles||SkyTeam|
|United Airlines||MileagePlus||Star Alliance|
|Southwest Airlines||Rapid Rewards||none|
Even if you fly another airline, you should endeavor to credit your miles to one of these airlines to minimize breakage and to maximize your balances in your main accounts. For instance, you may fly on Lufthansa and have the option of crediting the miles to its Miles & More program, but you should instead include your United MileagePlus number. United and Lufthansa are both members of Star Alliance so flights on one can be credited to each other’s loyalty programs. This strategy will also minimize accounting hassles.
You will sometimes open frequent-flyer accounts at less frequented airlines solely to use opportunistically their unique routes or values.