It is Tuesday, and by now you have to hope that every air traveler who set out for National Airport on Friday afternoon has made it to the right departure gate. We're talking here about one of the world's true user-unfriendly air terminals, where taxi passengers crawl in ever-tightening concentric circles and their counterparts on foot must hire guides to lead them from the Metro terminal to the airport front door. As Staff Writer Michael Specter wrote yesterday, National Airport is a terminal overwhelmed. It is one of two airports owned by Uncle Sam, and therein lies the heart of its troubles. National could use a new lease on life -- a lease held by a regional authority that could raise the revenue to fix both terminals.

There is little point in discussing what should be fixed first at National, however, until the transfer from federal to regional control can be made. Selling National and Dulles to a private buyer, as some suggest, might make a few dollars for the Treasury, but would risk installing a management more interested in profits than public service. The administration and the Senate have approved legislation to lease the terminals to a nonprofit regional authority with representation from Virginia, Maryland, the District and the federal government. With House passage, bonds could be floated and improvements undertaken.

At Dulles, a midfield terminal would be the first order of business. At National, the list is longer:

*Approaches: There should be a road system that separates arrivals from departures and cabs from other traffic. The Metro subway station and the terminal must be brought closer together.

*Buildings: The jumble of shacks, flats and covered walkways slapped together over the decades needs redesign, relocation or removal.

*Parking: Even with better cab, subway and bus approaches, more parking spaces must be provided.

sk,3 There are local residents living in the noise paths of National who hope nothing is ever done to make the place any more popular. That's not likely, given the interest of air travelers, airlines and Congress in keeping some sort of airport at this site near downtown. Better to talk about maintaining limitations on air traffic at National, while making it more useful and safe. But that is not something the federal government should have to pay for any more -- least of all when it could lease its two airports and let the users do the underwriting.