PITTSBURGH — US Airways' dominance at Pittsburgh International Airport continued to shrink Wednesday as it announced plans to cut nearly 40 percent of its flights by January and eliminate about 450 jobs.

The airline will cut its 108 daily flights in and out of Pittsburgh to just 68 by reducing US Airways' mainline flights from 31 to 22 and regional flights from 77 to 46.

US Airways agents and ramp employees will take over customer service and ground-handling duties for 350 employees of US Airways Express carrier PSA Airlines. Those workers, and 100 US Airways mainline employees, will be offered transfers.

The airline also will close its Pittsburgh flight crew base, leaving about 500 pilots and flight attendants to bid for trips starting in other cities.

"Unfortunately our ability to operate profitably from Pittsburgh has been sharply eroded over the past few years and the hub lost more than $40 million over the past 12 months alone," Doug Parker, chairman and CEO of US Airways Group Inc., said in a statement.

US Airways eliminated flights serving Erie; Chicago; Denver; Charleston, W.Va.; Norfolk, Va.; and Toronto. Decisions about cuts to cities served by regional carriers haven't been completed, the airline said.

"The other airlines at Pittsburgh International Airport have been growing, and origination passenger traffic is up by 11 percent," said Glenn Mahone, chairman of the Allegheny County Airport Authority. "We expect that other airlines, as they have done in the past, will fill in the gaps left by US Airways changes."

The announcement was a "direct result of increased competition and the addition of 13 low-cost carriers at Pittsburgh International Airport," said Allegheny County Executive Dan Onorato.

"What you're seeing is, US Airways can't compete in Pittsburgh. This is the marketplace playing out," he said.

US Airways said it remains committed to building a new 600-employee operations control center at Pittsburgh and will continue to employ 730 mechanics at its heavy maintenance base at the airport.

Robert Mann, a Port Washington, N.Y.-based airline consultant, said he doubted the announcement signaled any plans by US Airways to entirely exit the Pittsburgh market.

US Airways became leaner after America West Airlines' 2005 acquisition of the original US Airways, which had entered bankruptcy. But competing with low-cost carriers such as AirTran Holdings Inc., JetBlue Airways Corp. and Southwest Airlines Co. remains difficult in an industry that operates on narrow margins in the best of times, Mann said.