United Airlines will offer extra miles for its best customers

United Airlines will give extra MileagePlus miles to customers who purchase first and business class tickets under a promotion through the end of February.

It's another indication of how much the major three U.S. airlines want to attract high-fare paying passengers. This is only a short-term promotion, but passengers who buy pricey tickets will be rewarded with lots of extra miles. They'll get even more miles if they're United's most loyal customers. (On March 1, the entire makeup of United's MileagePlus program will change, which is probably why this promotion ends Feb. 28.) 

For those interested in such things, these are regular award miles and cannot be used to reach elite status. Below is the bonus mile chart United sent out in a press release. 

If you're having trouble reading the chart, keep this in mind. The only folks who are going to make out really well are travelers who flew 100,000 miles on United last year and buy first and business class fares on international and key cross-country flights. (New York-L.A. and New York-S.F.)

If this chart looks familiar, it's probably because American announced a similar policy last month. But American's promotion will last throughout all of 2015.