WASHINGTON (AP) _ Air traffic control for planes approaching the four major airports in the Washington-Baltimore region will be combined.

The Federal Aviation Administration said Monday it has decided to consolidate control of flights within 50 miles of the airports into a single center.

Currently, approach control is handled separately at Washington Dulles International Airport, Washington National Airport, Baltimore-Washington International Airport and Andrews Air Force Base.

The site for the new Potomac Terminal Radar Approach Control facility has yet to be determined, and the FAA said the schedule for the consolidation will depend on the availability of funds for the change.

Terminal approach control at airports directs planes within about 50 miles of an airport, turning them over to local airport tower controllers a couple of miles from the runway. Each airport will continue to have separate tower control for planes on final approach.

Having a single control facility for the regional airspace is expected to improve efficiency in handling planes, the FAA said. It will also allow consolidation of management, automation and controller work forces.

Whether that will lead to a change in the number of air traffic controllers working the area was not immediately known.

The FAA said it has been considering combining the four facilities since the late 1980s because of concerns the region's congested airspace could lead to delays in air traffic.

Despite construction of a new control tower at National Airport, the facility has experienced a series of radar and communications problems in recent years. On occasion, National controllers have had to switch to backup systems at Andrews.