Another airline is objecting to the big fee increases being proposed at Pittsburgh International Airport next year to offset the effects of fewer flights, particularly by US Airways.

AirTran Airways joined low-cost rival Southwest Airlines in raising concerns about the increases, which will be implemented in January by the Allegheny County Airport Authority as part of an $88.9 million budget adopted Friday.

AirTran spokeswoman Judy Graham-Weaver said in an e-mail that keeping operating costs as inexpensive as possible is an "integral part" of AirTran's efforts to provide low fares to travelers.

"For that reason we would not want to see any increase in our operating costs at Pittsburgh International Airport, especially at a time when we have had to deal with record-high fuel prices this year," she wrote.

Under the budget, landing fees will increase about 35 percent to $3.37 per 1,000 pounds; terminal fees, what the airport charges for rent inside the terminal, will go up by about 36 percent to $149.59 per square foot; and ramp fees, the rate charged for outdoor space where aircraft are parked, will nearly triple, increasing to $574.74 per lineal foot from $197.47. Southwest official said last week the carrier was "very concerned" about the increases and planned to work with the authority to see if there were ways they could be reduced. He couldn't say whether the hikes would force the airline to cut flights.

The increases are largely the result of the dramatic US Airways cutbacks in Pittsburgh over the last seven years, during which the airline has dropped hundreds of daily flights and eliminated the airport as a hub.

As flights and passenger volume have dropped, the costs to all airlines have increased. The authority is calculating that boardings will fall from 4.75 million this year to 4.1 million in 2009, less than half of what they were in 2001.