American is removing about 6.4 percent of its seats; in recent years, analysts say, travelers using frequent-flier awards have occupied about 11 percent.
Some industry analysts say sales of frequent-flier awards have become so entrenched that airlines will be hard-pressed to halt them.
The nation's seventh-largest airline attributed the deterioration in earnings to higher fuel and labor costs, lower fares and more frequent-flier awards.
Trans World Airlines has a new policy for redeeming unrestricted frequent-flier awards.
And last year alone, more than 13 million frequent-flier awards were redeemed.
Airlines have benefited from another feature: frequent-flier awards are more alluring than they deserve to be.
In recent weeks, several airlines have announced new fees for booking frequent-flier awards and, in some cases, paid tickets through an airline representative.
The new fees apply to paid tickets and frequent-flier awards.
And by preventing use of the tickets in a future year, the airlines avoid further growth in the immense backlog of unused frequent-flier awards.
Major airlines say they have devoted 7 percent to 9 percent of their miles flown to frequent-flier awards.