The National Transportation Safety Board announced yesterday that it will study National Airport and a half dozen other U.S. airports to see if federal safety standards need to be tightened.

The board said National was included because of "airport-related safety issues" uncovered by the investigation of the crash of Air Florida Flight 90, which hit the 14th Street bridge after taking off from National last January. The board has not selected the six to eight other airports to be examined, according to a spokesman.

The study will focus on how the Federal Aviation Administration devises and enforces standards for layout and equipment that airports must meet to be eligible to handle airline flights. Currently, 775 of the 6,200 public-access airports in the United States are so certified.

The study appears to be the latest round in a years-long campaign by the board to make certification standards stricter.

The study will examine such issues as the proper length for runway overrun areas, whether airports should post distance markers to tell pilots as they take off how much runway remains, and what level of preparation for crashes and fires should be required, the board said. All of these are issues raised by the Air Florida crash.

For instance, the overrun of the runway used by Flight 90 is 230 feet long. Some investigators have speculated that the crew might have aborted the take-off if the overrun had been longer.

Airports built today must have 1,000 feet of overrun to be certified. But under grandfather clauses, National is held only to standards in force when it opened in 1941. The FAA plans to lengthen the overrun of the runway Flight 90 used to 750 feet, but does not foresee meeting the 1,000-foot standard.

The study will compare grandfathered airports like National with those built after the current stricter standards were imposed in 1972.

Most of the raw data on National has already been gathered during the Air Florida investigation. The board's final report faulted the FAA for allowing the airport to become congested on the day of the accident, but did not cite its layout or equipment as a cause.

Civic groups for years have campaigned against National as unsafe, citing its comparatively short runways and overruns, the lack of approach instruments on some runways, the curved flight paths and its dense traffic. The FAA, which owns and operates National, counters that the airport is safe.

After the accident, Rep. Frank Wolf (R-Va.) asked the board to evaluate safety at the airport. Board chairman James Burnett responded in a letter that the board does not rate airports as "safe or unsafe" but "is concerned as to the adequacy of federal safety requirements for some airports . . . ."

Yesterday, Wolf welcomed the board's study, which will take more than six months to complete.

Eric Bernthal, president of the Coalition on Airport Problems, an umbrella group of civic organizations active over National, also lauded the study, but expressed concern that it might skirt the "core safety questions" at National, such as whether the runways are too short or the curved approach routes too difficult to fly.

A board official yesterday said that the board is addressing these two issues in separate programs.