Lots of ink and pixels have been devoted to the quest for an answer to the question, "When is the best time to buy airline tickets?" My pat answer has always been, "When they're on sale," but colleague George Hobica of SmarterTravel's sister site Airfarewatchdog says—and I agree—that you can't predict the next sale. Nevertheless, folks keep trying. The latest data from a new report by CheapAir.com might provide some answers to this often-debated conundrum.