THE PLAN to National Airport, now pending before Secretary of Transportation Neil Goldschmidt and FAA Administrator Langhorne Bond, is a disaster. It would enshrine Dulles as the world's greatest secondary airfield and it would destroy the last trace of any hope that someday people will be able to live and work and walk along the Potomac River in comfort.

Dulles was built, as those who have been around this city for 20 years will remember, to become Washington's major "jetport." The decision to pour $120 million -- in 1960 dollars -- into it was predicated on belief that National Airport was too crowded, too noisy and too dangerous. Now, with National handling almost four times as many passengers as it did then, generating more noise and presenting equally serious safety problems, the planners are urging that it becomes everlarger and that it remain this city's major airport indefinitely.

Why?

The answer is that almost everyone has falen into the habit of believing that National is an must always be thiscommunity's major airport. We fell into the trap ourselves a few weeks ago when we described the plan for National's future as not too bad "as long as" that airport is to be No. 1.

But -- as the National Capital Planning Commission asked yesterday --should National continue to be Washington's major airport? It is handling hundreds of planes -- jets -- each day for which it is too small. It is coping with a passenger load that woulddestroy most airports. And it is a terrible neighbor to tens of thousandsof people who live and work and play under it flight paths. No community that had control over its own destiny would have tolerated National during all these years when Dulles stood in isolated splendor. National would have -- should have -- gone the way of the in-town airports in Chicago, Dallas and Kansas City long ago.

National has remained inviolate, however, because of the belief that air travelers, especially if they are members of Congress, have an inalienable right to fly into the middle of Washington. That's why the first opportunity to make Dulles the major airport -- the proposal to bar jets from National -- was ignored for 15 years. That's why the second opportunity --putting a 500-mile limit on flights in and out of National -- was repudiated after the FAA seized it briefly. And that's why the current and probably last opportunity -- the introduction of wide-bodied, small jets -- is about to disappear. All the thinking of FAA's planners concerns what to do with the passengers who will be "turned away" from National if limits are placed on its growth.

Under the FAA's proposal, the number of flights (and the noise they generate) at National would be reduced somewhat. But the number of passengers would be allowed to increase by 20 percent to 18 million a year. By the FAA's estimate, Dulles mighthandle that many passengers sometime around the end of the century. In other words, the airport built in 1962 to be Washington's major jetport might reach parity with National on its 40th birthday.

It does not have to be this way. There is nothing, in law or anywhere else, that says National must be Washington's major airport. A proper plan for its future would include: a rigorously enforced curfew (which the FAA is proposing), a requirement that each takeoff and landing of the new wide-bodied jets replace two operations of the other planes, and the shrinkage to 500 miles of the perimeter inside which flights to and from National are permitted.

The phased introduction of those threer rules would transfer hundreds of thousands of passengers to Dulles (or Baltimore-Washington International) and require the installation of the one thing whose absence has mostly seriously thwarted the development of Dulles: a quick, convenient and cheap way of getting passengers to and from the airport. But these rules would eliminate the need for what will inevitably follow if the Faa's proposed plan for National is adopted: the totalrenovation of that airport's terminal facilities, which would mean years of contruction and turmoil while the terminal was being moved closer to the Metro stop.

What a waste of money that would be. Why not put the same funds into providing better ground transportation to Dulles, even if that requires special service for members of Congress? That's the question Secretary Goldschmidt and Mr. Bond should put to their planners, along with a reminder that the air space over a city is more precious to the people who live and work there than it is to the airplanes that fly through and despoil it.