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.

Even so, on average base airfares outside of the travel periods for the recently launched sale fares are higher today than in the last few years, said Rick Seaney, head of airfare research site FareCompare.com. He noted there were 30 attempted airfare hikes between summer 2007 and summer 2008, two-thirds of which were successful.

The fare sales do not affect fees for baggage or other services charged by some of the carriers.

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.

“They’re not sure what’s going to happen at the last minute,” Seaney said.

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.

Carriers that have launched fare sales recently include AirTran Airways, Virgin America, JetBlue Airways, Southwest Airlines, American Airlines and United.