DULLES AIRPORT is in a nose dive. The airport 25 miles from Washington, handles fewer passengers than either National Airport or Baltimore-washington International. And now Eastern Airlines, a major passenger carrier, is withdrawing from Dulles. Should the airport be closed? Or can something be done to attract more people and planes?

The answers concern ground transportation: getting people to and from the airport. There is no subway, no train and only an occasional bus to Dulles from Washington. The car is the principal means of transportation for travelers using the airport. Ideally, a subway link should be built or regular Metrobus service established.

But a rail spur or bus link takes planning and the sort of influence that can be translated into dollars. That influence lies with the airport's owner, the U.S. government. So far, hopes for Dulles' future have all fallen victim to the low priority given Dulles by the federal government and the high priority given National Airport by its owner, the same U.S. government. National is convenient to the city and suburbs and, as a result, is popular with congressmen. It offers the connections to major airports as well as the commuter flights that are essential to an airport in the nation's capital. From a passenger's point of view, National is a model of what an airport for this city should be: easy to reach and offering a full selection of flights.Consequently, National has outstripped Dulles in the battle for passengers and flights, though Dulles was built more than 20 years ago as this area's airport of the future.

But passenger convenience is not the only criterion off excellence in an airport. There are questions regarding passenger safety, the movement of people in and out of the airport without congestion, noise and air pollution over populous places and the danger posed by having a major airport in a highly populated area. On all those counts, National Airport comes up short and Dulles is a winner. The challenge, then, is to make Dulles a winner on its lone shortcoming: its inaccessibility to most people who live in the area.

Today one other factor key to Dulles' future is due to be unveiled. It will come in the form of a decision by the Federal Aviation Administration on the future of National Airport. The decision could limit the type of planes coming into National as well as the distance of flights and out of the airport. But even an FAA decision that would severely limit National's services to Washingtonians is not sure to cure what ails Dulles. Washington passengers can still go to BWI and avoid Dulles if National is unable to provide the service they need.What Dulles must do, regardless of the decision on National, is find a convenient way for people from Washington and its suburbs to get to the airport.