Most customers who book way in advance are in one of two classes: really price-sensitive, or really time-sensitive. The airlines try to figure out which you ar

Most customers who book way in advance are in one of two classes: really price-sensitive, or really time-sensitive. The airlines try to figure out which you are through the special offers. As such, they'll set the base rate higher than the 3-month out rate to catch some extra revenue from the time-sensitive people, and then have "special offers" to induce the price-sensitive people to book.