ATLANTA — A wave of fare sales has spread across the airline industry in the early days of the new year as the weak economy continues to put pressure on carriers to fill seats even after they drastically reduced capacity and some expressed willingness to cut more.

Many experts and even executives at some airlines had expected that after deep capacity cuts went into effect starting in September, the number of fare sales going forward would be fewer and farther between. But fuel prices have come down significantly, and the weak economy has eroded demand for air travel.

It's not unusual for airlines to announce fare sales in January — there were 17 or 18 announced in January 2008 — but what's different for several carriers this year is that the discounts are for travel extending as late as April, May or June, Seaney said. The sales last January were typically for travel through March, he said.

Seaney said he believes uncertainty in the economy is the reason for the change.

A handful of major carriers and discount carriers have launched fare sales since Dec. 31. Others are expected to follow with sales of their own, or to at least match discounts offered by rivals on competitive routes, Seaney said.

Discount carrier AirTran Airways, a subsidiary of Orlando, Fla.-based AirTran Holdings, said Tuesday it was offering a nationwide fare sale with one-way fares starting as low as $39. The fares, available for purchase through Jan. 15, are good for travel to and from Florida and San Juan, Puerto Rico, through March 11, while all other sale fares are good for travel through May 20.