The Federal Aviation Administration agreed yesterday to take a series of steps to reduce air traffic control delays that the airlines contend cost them billions of dollars a year.

In particular, the FAA said it would strengthen the decision-making authority of the FAA Command Center in Herndon, allowing it to assert more authority over various air traffic control centers around the country.

The problem, according to the airlines, centers on the air traffic control systems' inability to make decisions quickly about the flow of airline traffic in bad weather or during abnormal circumstances generally.

The slow process, they argue, hampers their ability to make decisions on flight cancellations or on the rerouting of passengers. That in turn can produce the delays and confusion at airports that so angers the flying public.

Jack Ryan, the Air Transport Association's vice president for air traffic management, said decision-making power is now divided between the command center and the local centers, and decisions often take too long as discussions and disagreements drag on. "Someone needs to exert control," Ryan said.

The command center, once called "flow control," coordinates the movement of aircraft across the country. If weather or some operational problem, such as a closed runway, limits the ability of an airport or a region to handle its normal air traffic flow, the center can take various actions to reduce the number of planes in the sky. That can include holding planes on the ground.

Ryan said the airlines await details on exactly how the command center will be given more power. FAA officials decided to take action after meetings with the ATA and another airline trade group, the Regional Airline Association.

The FAA also agreed to limit the use of special restrictions that lengthen the spacing between aircraft in flight. These "miles in trail" restrictions are often used in bad weather as a safety measure, but they also cut down on the number of planes that can use the national airspace. Airlines have complained that miles-in-trail restrictions are overused and excessive.

The FAA agreed to review the conditions under which it orders "ground stops"--holding airplanes on the ground if weather or other conditions could prevent them from landing immediately at their destination.

The agreements follow complaints by several airline chief executives that FAA air traffic inadequacies are costing billions of dollars in lost revenue and costs. The ATA, composed of major airlines, estimated that in 1998, air traffic control delayed 308,000 flights at a cost of $4.1 billion, a 5 percent increase from 1997. FAA officials have said that air traffic delays can often be attributed to scheduling decisions by airlines.

In what appeared to be a coordinated airline campaign, several top airline officials warned of the cost of air traffic delays in speeches and congressional testimony over the past month.

United Airlines Chairman James Goodwin told a business group in Chicago that air traffic control delays cost United $10 million to $20 million a month. More than 16,000 United flights have been canceled so far this year, he said.

Continental Airlines Chairman Gordon Bethune told the Aero Club in Washington that the main cause of passenger dissatisfaction is "the inability of our nation's air traffic control system to allow the efficient use of airports and airways." Bethune called for the privatization of the air traffic control system.

Robert Baker, executive vice president for operations of American Airlines, also testified to a congressional committee that delays and congestion have reached a critical point.