From the New York Times online:
2. BUY ON TUESDAY Most airlines begin sales on Monday evenings, and by the following day other airlines have usually matched the lowered fares on the same routes, said Anne McDermott, editor at Farecompare.com, which tracks price trends. Last month, for example, Virgin America had a sale on Dec. 13, with one-way fares as low as $79 on some routes, according to Farecompare. The next day, there were sales from AirTran, Southwest and American, with one-way fares from $59. Because sales are hard to predict, travelers looking for the best deal should start their searches three to four months in advance, when airlines begin to look closely at which routes may need a sale to fill seats.
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