Thanks to a better understanding of its booking patterns, Mr. Casey said American now overbooked about 5 percent of its seats, down from about 12 percent a decade ago.

In 1999, the company said it had on average about 72 percent of its seats filled and 35.2 out of every 10,000 seats were oversold. Last year, the company filled 82 percent of its seats while the number of oversold seats had dropped to 8.3 for each 10,000 passengers.