Average airfares at Hartsfield-Jackson International Airport declined 3.4 percent in the fourth quarter of last year compared with the same period of 2009 -- even as fares rose 5.2 percent nationally.

But fares this summer will be up noticeably from last year, according to one estimate.

The average domestic air fare in Atlanta was $318 in the fourth quarter, down from $330 a year earlier, according to the U.S. Bureau of Transportation Statistics. The national average domestic fare was $337, up from $320 a year earlier.

Averages fares reported by the government do not include baggage fees and other fees paid at the airport or on the plane.

Atlanta fares may have declined due to spirited competition between AirTran Airways and Delta Air Lines, said Tom Parsons, CEO of BestFares.com. "AirTran was pretty aggressive with air fare sales last year," Parsons said.

However, airlines including AirTran have been raising fares this year due to higher fuel costs. Airlines have attempted 12 fare hikes this year, according to FareCompare.com CEO Rick Seaney. Such increases usually only stick if all major carriers match.

Bing Travel predicts air fares will be up 15 percent this summer compared with last year, adding that May 30 to June 5 is the cheapest week to travel this summer. .

Atlanta's airline landscape will be in flux over the next year or two after this week's buyout of AirTran by Southwest Airlines. Terry Trippler, a travel expert who owns airlinerulestoknow.com, said he thinks Atlanta fares will stabilize with Southwest entering the market.

Parsons said AirTran often has better offers than Southwest, but Southwest will likely do aggressive fare sales to introduce itself in Atlanta. Southwest continues to operate AirTran as a subsidiary for now.