The Federal Aviation Administration said yesterday that it has launched a new digital air traffic system that will improve safety and reduce fuel costs for planes flying over the Atlantic and Pacific oceans.

The $548 million program now operates only over the Atlantic, out of a center in New York, but the FAA plans to expand the program to facilities in Oakland, Calif., and Anchorage, which handle traffic from the Arctic to the South Pacific. It replaces a low-tech system that required pilots to report their longitude and latitude every 50 minutes to an air traffic facility because the oceans are not covered by radar.

"Before, we were relying on crackly voice communication," which required planes to remain 100 nautical miles apart from one another, said FAA Administrator Marion C. Blakey.

Under the new system, planes use onboard global positioning devices to transmit their location to satellites that then beam the data to air traffic controllers. "It's a combination of safety and efficiency in a package that really is a breakthrough," Blakey said.

Blakey said the system, known as Advanced Technologies and Oceanic Procedures, will soon enable planes to fly 50 miles from one another over the Atlantic and 30 miles apart over the Pacific on routes such as California to Hawaii. It also will allow pilots to take more direct routes and avoid bad weather conditions, which amounts to substantial fuel savings for airlines.

International air traffic grew 16 percent between 2003 and 2004, according to the FAA, and it is expected to grow 38 percent from 2004 through 2010.

For domestic flights, air traffic controllers use radar to locate an aircraft and talk on radios to provide direction on where the plane should fly. Radar extends 250 miles from the coasts, so pilots and air traffic controllers have to rely on other methods when planes fly over the ocean.

A pilot heading over the ocean from San Francisco to Tokyo, for example, is required to report a 10-character longitude and a nine-character latitude every 500 miles. Controllers monitor traffic using paper strips containing each plane's information to keep track of where one aircraft is in relation to others.

The new system in place over the Atlantic reduces the number of interactions between pilots and controllers. "The workload goes down" with the system, said Dave Ford, the FAA's director of ocean and offshore services. A more automated system reduces the risk of human error, he said. "It's more accurate."

Ford estimated the system would provide $2.5 billion in savings through 2013 in airline fuel costs and in expenses associated with delays.

The system will go into operation in Oakland this fall and in Anchorage by spring 2006. Lockheed Martin Corp. received a $247 million contract to help develop the program.