Northern Virginia antinoise activists criticized legislation yesterday that would shift control of Dulles and National airports from the federal government to a regional authority, but supporters of the measure said any major changes in the bill could kill it.

Thomas White, president of the Fairfax County Federation of Citizens Associations, told the Senate aviation subcommittee that his group supports the concept of a regional authority. But he said Congress should not act on an airport transfer bill unless it includes a "cap" or ceiling on the number of passengers using National.

The bill also must give the regional authority the power to reduce the number of flights at National, White said.

An existing annual ceiling of 16 million passengers at National would be eliminated by the bill. The measure also would freeze the number of airline takeoffs and landings at National at 37 an hour.

"If nothing in the bill is changed, it will be tough going with citizens groups," said Fred E. Wood, chairman of the Washington Airports Council, an antinoise group. John G. Milliken, chairman of the Arlington County Board, said Arlington officials also support several changes to strengthen antinoise provisions.

But Sen. Paul S. Trible Jr. (R-Va.) and former Virginia governor Linwood Holton, the head of a 15-member commission on the airport issue, said after the hearings that they opposed any significant alterations. They said the legislation is a carefully drawn compromise that could fall apart if changes are made.

Trible said the Senate Commerce Committee will vote on the bill later this month or immediately after the August recess. Trible said he was "optimistic" that the bill will win committee approval.

Virginia officials support the measure, while Maryland officials oppose it, arguing that it will give National and Dulles a competitive advantage over Baltimore-Washington International Airport.

Under the proposal, the regional authority would sell bonds to finance massive improvements at the Virginia airports. The regional authority would pay the federal government $47 million for the airports and assume $33 million in unfunded employe pension liability.

Maryland officials argue that the price tag is too low.

Only a handful of Commerce Committee members attended yesterday's session, the third Senate hearing on the legislation. But those present seemed generally to favor the concept.

"I started out on this skeptical and so informed [Virginia Gov.] Chuck Robb . . . but the more I listen to, the more it seems to make sense," said Sen. Jay Rockefeller (D-W.Va.), who added that he still had some questions about how the airports would operate.

The only suggestion that appeared to have no chance of congressional support was one by Alexandria Mayor James P. Moran. He said his "pet peeve" is the special parking lot at National Airport set aside for members of Congress, diplomats and Supreme Court justices.

Moran suggested that members of Congress let the public use all or part of the special lot, which is more convenient than most other lots.

The senators laughed.