Thirty-eight members of Congress, complaining they often are forced to use the public parking lots at National Airport, have asked the Federal Aviation Administration to kick Supreme Court justices and diplomats out of their free parking lot.

Representatives have to cope with "irregular and unpredictable time constraints not imposed upon either members of the Supreme Court or the Diplomatic Corps," said a letter from Rep. Philip M. Crane (R-Ill.) and 37 other Republicans and Democrats. Members of Congress "who truly need the ready access to parking because of the unpredictable nature of the voting" in Congress need to be assured that they will have convenient parking available whenever they drive to the airport, the group said.

The congressional lot, located within a few steps of the main passenger terminal, has long been one of the most controversial perks accorded the 535 members of Congress, the nine Supreme Court justices and diplomats. Local officials and many passengers have eyed the lot and its approximately 100 spaces with envy and called for its closing, but because the airport is operated by the federal government the complaints have gone unanswered.

In their letter, the representatives dismissed the needs of the justices and diplomats. " . . . Supreme Court Justices and Ambassadors are traditionally driven to the airport," said the letter. Thus, it said, many of the spaces are being used by court and embassy staffers.

Not so, said Toni House of the Supreme Court public information office. "I'm quite certain that those spaces are not used by the Supreme Court staff," she said yesterday. "They're used only by the justices or by a car going to pick them up."

When the congressional lot is full -- and FAA police said it is most of the time -- the officials are directed to a nearby public lot, where a few more spaces are reserved for them. If those are filled, the legislators must join the public in seeking space in public lots that are often filled to capacity.

"Most of the time there is competition to get into those VIP spaces," said Thomas Holderness, who until recently was head of the airport police.

"Of course, you have a lot of resentment on the part of the general public," said Holderness. "When you are hassled and a poor old Joe Blow citizen carrying his bags across a highway, and some congressman pulls into his private space, there's bound to be some animosity."

Carol Carmody of the FAA government affairs office said that a letter responding to the complaint would be sent in a few days. She said the FAA will probably review the parking to assess the severity of the legislators' problem.

The congressional parking issue arose earlier this year during hearings on a Senate bill to transfer National airport from the FAA to a regional authority.

Alexandria Mayor James P. Moran Jr. suggested that the authority should open the convenient VIP lot to the public. But Virginia supporters of the bill quickly hushed such talk, fearing it would kill the bill.

The bill has been approved by the Senate Commerce committee and, if enacted, is expected to contain some assurance that members of Congress can have continued parking privileges at Washington's two federally owned airports, National and Dulles.

The parking dilemma appears to have generated bipartisan concern. Signers included House Minority Leader Robert H. Michel (R-Ill.), Guy Vander Jagt (R-Mich.), Helen D. Bentley (R-Md.) and Democrats E (Kika) de la Garza (Texas), Carl C. Perkins (Ky.), Leon Panetta (Calif.), George Miller (Calif.), and Martin A. Russo (Ill).