With fanfare befitting the launching of an ocean liner, federal aviation officials dedicated a new, high-speed computer system yesterday that they said would reduce air travel delays and ease pressures on controllers at the region's air traffic center in Leesburg.

The new computer is 10 times as fast and can handle four to five times the number of airplanes as the equipment that is being replaced at the Washington Air Route Traffic Control Center, which supervises flights in some of the busiest airspace in the world and directs planes to and from National, Dulles International and Baltimore-Washington International airports, among others.

The IBM computer system has been installed as part of a 12-year, $12.2 billion modernization of the nation's air traffic control system.

The new computer "is a major step toward meeting the rapidly growing demand for air traffic services," said Acting Transportation Secretary James H. Burnley IV. "As air traffic continues to grow, this system has the capacity to grow with it."

The dedication ceremony comes at a time of mounting public concern over air safety and the ability of the nation's air traffic control system to handle an ever-increasing number of flights. Tensions run particularly high at the Federal Aviation Administration's Leesburg center, whose 300 controllers handled more than 2.2 million flights last year.

One of 20 so-called en route centers around the nation, Leesburg has had a number of computer failures in recent months, including one in July that caused delays of up to 70 minutes in the heavily traveled Northeast corridor. Last year, the Leesburg center led the nation in controller errors, with 83.

Rarely has a new piece of hardware been heralded with such enthusiasm. About 200 people turned out for yesterday's dedication ceremony at the center, where officials had converted a warehouse-like room into a curtain-draped auditorium with a podium at one end.

In addition to Burnley, speakers included Rep. Frank R. Wolf (R-Va.) and FAA Administrator T. Allan McArtor, who inaugurated the system by engaging in a radio conversation with the crew of a passing United Air Lines jet on the way to Chicago.

"Computer outages should markedly improve," McArtor said at a news conference after the ceremony. "I think the public's confidence is very much on the rise."

The IBM host computer system was designed to replace the IBM 9020, which was installed at the Leesburg center in 1972. Washington is the fifth center to start using the new computer.

"The capacity means that in very busy times the controller will not have to worry about the system becoming saturated" and overloading the computer, said William Carson, director of air traffic control programs for IBM. "There's more horsepower." There is nothing new for controllers to learn; the host is simply an upgrade. It is to serve as an interim system while the FAA develops an automated next generation computer network.

Charles Reavis, air traffic manager at the Leesburg center, predicted that the new system would raise morale among controllers.

"I would think that the biggest thing is that this computer is going to renew the controller's confidence with our equipment," he said. "We had a number of outages during the summer and since {the new system} has been up it has been very reliable."

In addition to expanded capacity, the host computer has the ability to perform several important safety functions, officials said. One is a "conflict alert" feature that can detect aircraft flying on a collision course and warn controllers. Another will issue an alert if an aircraft strays into an area without authorization.