Fairfax County Supervisor Martha V. Pennino's head is crowned with a striking mound of flaxen blond hair that, quite simply, commands attention.

But Mrs. Pennino, now in her 10th year as supervisor representing the fast-growing Centerville district in western Fairfax, does not have to rely on her well coifed looks to attract notive. She can do that, and frequently has, with a variety of unpredictable proposals that, depending on your point of view, are visionary or wrong-headed, inspired or silly.

On the eve of the Concorde supersonic transport plane's first scheduled flight to Dulles Internation Airport last year, Mrs. Pennino proposed that the county hang a red lantern in the Massey Building governmental tower to warn county residents. The supervisors, earlier in the year, had declared a legal war against the SST.

The lantern, actually a sheet of red plastic taped to a window and illuminated by a floodlight, was duly hung and was seen by many of the thousands of residents who drove to the airport to gawk at the sleek, delta-winged aircraft with British markings.

In another proposal last year, Mrs. Pennino called on the county government to draw up a "code of accountability and responsibility" for juveniles and their parents. "The citizens of Fairfax County are disturbed!" she declared, citing "problems of vandelism, roving gangs, shoplifting and harrassment."

But her proposal, being pure Pennino, was not a routine stop to "law-and-order" people.

"If the public is not willing to become fully involved in such a program," she said at the time, "The only alternative would be more police, and I am sure no one would want to see Fairfax become a police state."

Mrs. Pennino is a Democrat, but it is difficult to place her in the political spectrum from conservative to liberal. She called for stronger local landuse controls, but eight years ago she enraged many environmentalists by backing a bond referendum question - defested by the voters - that would have put sewers in the historic and largely undeveloped Bull Run area in the western corner of the county.

In her proposal for a countywide code of behavior, she said "immeddiate attention (should be given) to what standard of behavior and responsibility is acceptable by persons living in Fairfax County public and subsidized housing" - words that angered officials in the county's public-housing program.

But early in her political career, as a member of the Vienna Town Council in the 1960s, she won the adoption by the Council of a human rights policy. And as a supervisor she helped lead the fight for resoltuions supporting the Equal Rights Amendment and open housing.

Two issues for which she had doen a lot of bleeding are opening to the Dulles Airport Access Road to commuter traffic and a local-option sales tax to give Fairfax a new revenue source.

Five times she had asked the supervisors to endorse opening the Dulles road, limited to airport users by the Federal Aviation Administration, which owns it. Five times she was defeated.

Then, last Monday, by a 5-to-4 vote, the Board backed her proposal, a testament to her persistent advocacy and lobbying of the swing vote, Supervisor John P. Shacochis (R-Dranesville).

Her fight for the local-option sales tax, although it started promisingly with endorsement by the Board and the Virginia Municipal League and [TEXT OMITTED FROM SOURCE] in defeat in the General Assemby.

Irrespressible, she say, "I was whipped, but you can't feel too much like a loser if you get whipped by the General Assembly . . . It was an election-year decision, and the people in the Assembly lacked political courage."

Mrs. Pennino's constituency includes the new town of Reston, which leans toward a liberal activism, and mor typically, established subdivisions, most of whose residents prefer a go-slow approach.

Her advocacy of the Equal Rights Amendment, which she carried to all the civic association in her distict, displeases many people, but she proudly recounts the reaction of oen of them: "'Mrs. Pennino,' she told me we don't agree with you, but we know you're doing it because you feel it's right.'"

On the Board, which has fewer liberals than the previous one, Mrs. Pennino is able to shepherd through social issues that might otherwise die or be emasculated. Sometimes she has to use a little camouflage, though.

After the State Supreme Court outlawed collective bargaining by public-employee unions, it appeared the Fairfax Education Association and other public-employee unions in the county might not be able to continue collecting dues automatically from their members' paychecks. There was sentiment on the Board, led by Chairman John F. Herrity, to end the arrangement.

In conversation outside the Board room, Mrs. Pennino can say of unions, "Where would the little people be without them?" But taking a prounion stand in Virginia, even Northern Virginia, is only slightly less damaging for a a politician than advocating the legalization of marijuana.

When the dues checkoff question came up, Mrs. Pennino noted that many organizations, including the Policemen's Benevolent Association, deduct dues automatically - and "these are good, loyal employees."

A majority of the supervisors, unable to quarrel with those sentiments, approved the checkoff, a decision that will keep the public-employee unions alive even if they can't bargain with the county.

Of her defeats as a supervisor, Mrs. Pennino says, "I'm not tough-skinned, but I heal easily."

When the outcome is more successful, she say: "Sometimes when the Board does something that is so right and so beautiful, I am actually moved to tears."