Continental Airlines plans to eliminate nearly one-third of its flights from Dulles International Airport this fall, leaving United Air Lines the dominant carrier there.

Continental, which operates 80 flights a day out of the rapidly growing Northern Virginia airport, plans to cut back to a number "in the low 50s," according to Continental spokesman Rick Scott. The cuts will take effect Sept. 9. United plans to maintain its current 87 daily flights from Dulles, a United spokesman said.

In January, Continental announced it was absorbing the operations of New York Air, People Express and Frontier and that it planned to beef up its Dulles schedule to 97 departures a day, making it one of the airline's four major hubs. (A hub is a major base of operations for an airline where many flights converge to exchange passengers.) New York Air had used Dulles as a major base of operations before the consolidation.

At the time, Continental also announced that it was acquiring the midfield terminal operated by Presidential Airways and that Presidential would fly under the banner of Continental Jet Express providing feeder service to Continental.

The anticipated cutbacks are a result of the normal decline in air travel that comes at the end of the summer and of a consolidation in service by the carrier, Scott said. In some cases Continental Jet Express will pick up the service, he said.

Since Continental absorbed the operations of the other carriers, it has been plagued by service problems. This has resulted in Continental topping the list of airlines in number of consumer complaints to the Department of Transportation. Thomas G. Morr, president of the Washington Dulles Task Force, a private group that promotes the airport, said that he has been told that the airline plans to consolidate its schedule "to concentrate on improving the day-in, day-out quality of what they are providing the customers, and then ultimately they will resume their growth here."

As a result of the cutback, Continental will reduce its Dulles work force, currently 1,100 workers, Scott said. The number of jobs to be cut has not been determined, he said, but affected workers will be offered a chance to transfer. Most of the reduction will be brought about by Continental's flying less frequently to some destinations rather than by dropping destinations served from Dulles. Scott said, however, that Continental will eliminate service to Greenville/Spartanburg, S.C., and to New York's La Guardia airports. He noted, however, that the airline will provide service to Newark Airport, which serves the same general area as La Guardia.

The cutback does not reflect any reduced commitment to Dulles as a hub, Scott said.

"Dulles is absolutely still a hub and continues to be, and there may be additional flights going in there in the months ahead," he said.