AirTran and Southwest launched fare sales a week ago and are now giving travelers a bigger window for low-priced fares. "The airlines need to start focusing on filling up those seats for the fall because the market is going to be soft," said Tom Parsons, CEO of Bestfares.com. "The only question when this sale is over is how many hours you have to wait for the next one. ... It's going to be nonstop."