KEY PARTS to the puzzle are still scattered, but necessary elements of support for a regional takeover of National and Dulles International airports are falling into place. With continued understanding and negotiation around the region and in Congress, a successful transfer of these two facilities from federal to local management could bring balance as well as sensitive noise control to the air traffic system for Greater Washington. The latest support came Thursday, when the country's major airlines endorsed the transfer -- though not without some conditions attached.

The airlines' support -- in the form of a vote by members of the Air Transport Association -- is critical to any decision by Congress. Traditionally, the traveling members of the House and Senate and top airline officials have enjoyed the benefits of federal control over National, the lawmakers' regular port of getaway. Not only are the airlines supporting removal of a restriction on passenger traffic at National, but also they are urging that rules be adopted to grant post-curfew landing rights at National for all new-technology aircraft with engines that meet the most stringent federal noise standards.

But just as important to the takeover as airline support is backing from those living near National -- and that has yet to materialize. People who have been battling the whoosh and roar of jets for years tend to bristle automatically at anything that might possibly mean more passengers, flights or late-night activity at the airport. Still, before they organize any full-bore effort to oppose the airlines or to block the regional takeover now being discussed, they should consider the alternative: continued federal control, with Congress in the pilot's seat and Dulles sounding emptier by the hour.

Regional control of National and Dulles is a matter of home rule -- and as such should leave stipulations, conditions, rules and regulations to the authority that would take over. This should mean refraining from loading the takeover agreement with a whole set of federal do's and don'ts. Once regional control is a fact, the authority can take whatever actions it deems necessary to respond to it constituency.

Transportation Secretary Elizabeth Hanford Dole initiated this important airport transfer proposal, and a commission headed by former Virginia governor Linwood Holton has fashioned a sound compromise that can work to the advantage of the entire region. Unless local residents prefer continuing to grovel on Capitol Hill for airport favors, they should seize the opportunity to press for genuine regional home rule over air transportation policy.