To some cynics, Dulles International Airport is the most beautiful aeronautical museum in the world. It's a nice place to visit, they say, but don't expect to find a flight from there.

But yesterday a blue-chip crowd of 400 business executives and local, state, federal and civic officials (including the two congressmen serving Northern Virginia) got together to boost Dulles as an airport rather than an architectural showplace.

The image-burnishing session, held at a hotel appropriately just off the Dulles Access Highway exit in Reston, was sponsored by the Fairfax County Chamber of Commerce, which has been taking an increasingly active role in shaping policies affecting economic development.

Phillip Reilly, first vice president of the chamber, surveyed the packed room, which included the chief executives of several major corporations located in Fairfax, and said: "They want flights, and they are not going to sit back and wait."

The topic of the gathering was "Dulles Airport -- Hub of World Trade." In smaller print on the program was the important qualification: "what will it take to make this happen?"

Not surprisingly, there were many answers. John F. Herrity, chairman of the Fairfax Board of Supervisors, said Dulles will get busier when it is served by better ground transportation. Toward that end, Herrity lobbied for three roads: the extension of the Dulles Highway to I-66 inside the Capital Beltway, unlimited-access lanes parallel to the limited-access Dulles road and the Springfield Bypass (also known as the Fairfax Parkway).

Not coincidentally, the Fairfax chamber and the county's business community are staunch supporters of all three roads. However, some citizen groups hotly oppose a Springfield Bypass that would extend all the way from Route 7 in the north part of the county to Route 1 in the southern part. f

The airlines represented at the meeting said the answer to making Dulles a busier airport lies with its landlord, the federal government. Dulles, like National Airport, is owned and operated by the Federal Aviation Administration.

"The FAA is going to determine how this airport develops," said Charles E. Griffith III, an assistant vice president of American Airlines. "The carriers can't create a major hub by themselves."

Griffith also defended American's controversial decision to ignore the 650-mile-perimeter rule for service to and from National -- a limit aimed at encouraging airlines to use Dulles for their longer-haul flights.

"The discriminating perimeter rule is not the way to encourage traffic at Dulles," Griffith said, noting that his airline competitors are able to evade the restriction because certain cities which they serve and which are more than 650 miles from Washington (such as Chicago, St. Louis and Minneapolis) are specifically excluded.

One of the fears of Dulles' supporters is that the Reagan administration's deregulation policies could cause even more problems for the airport. For example, if the administration vetos or softens the proposed 18-million-pssenger annual ceiling at National (a policy supported by Northern Virginia localities), the closer-in airport could continue to attract traffic that otherwise might go to Dulles.

Rep. Frank Wolf (R-Va.), whose district includes Arlington (which hates the airplane noise from National's flights) and Fairfax (whose business leaders want to see a busier Dulles), is an unflinching ideological supporter of the president. But he warned yesterday's gathering that "if the [federal] policy becomes one of open skies, it will be the death knell for Dulles Airport at least for the foreseeable future."