Aeroflot Flight 261 was set to take off from Moscow as soon as four Soviet Jewish families stepped on board.

Nina Raben, Mark Belenky and their daughter had won their cherished exit visas 10 days before. Now, Soviet customs was behind them. Vienna, Rome and the United States lay ahead.

In these final moments in their homeland, there were shouts of goodbye and tearful glances between Raben, who was heading for the United States, and her younger sister, who was forced to stay behind. A narrow counter and perhaps 12 steps were all that separated the sisters.

"But we were on the other side of the frontier," Belenky remembered. "These 12 steps you cannot cross."

Indeed, it had taken his family eight years to take those steps, from 1979, when they applied for exit visas, through the years of official refusal, to April 27, when the visas were finally granted.

So much had happened in between. And in the end, so much had failed to happen: Elena Raben, her husband Vladimir and their 9-year-old son had been denied visas once again, just as the rest of the family won its long fight. Like so many refuseniks, as Jews denied visas are known, the Rabens learned that freedom and separation go hand in hand.

"Only during a time of war are families torn apart," Nina Raben said last week, still struggling to comprehend what had gone wrong. "It is not a war now."

But Raben, who has settled with her family in Alexandria, is waging her own private war. Each day since she stepped off the plane and into the free world, she has worked to get Elena Raben and her family out.

There were visits to diplomats in Vienna and protests at the Soviet Embassy in Rome while the family spent three months in the emigration process. Since arriving in the United States Aug. 4, Nina Raben has told her story on radio, appealed to members of Congress and written to governors and First Lady Nancy Reagan.

She sees a special chance for her cause when Soviet leader Mikhail Gorbachev visits Washington next month. She and her family plan to carry banners in the demonstration planned by Jewish groups Dec. 6. "It is important for Gorbachev to see how powerful the Jewish community is," she said.

At the time of important meetings with the United States, she says, Soviet leaders "want to show Americans they can be nice." If ever there were a chance for her sister's emigration, Raben believes, "the time is now."

Although she sees Gorbachev "as the embodiment of the regime" -- a regime she does not like -- she thinks he has been "a blessing to the country" because of his reforms.

"There are very big changes" in the Soviet Union, Raben said. "But one thing remains. Human life does not have any value. You are still government property."

It was a lesson Raben learned as a little girl. She never knew her grandfather, who was imprisoned and killed in the Stalinist purges. Her grandmother was gone for years, too, snatched from home by police one night and sent into exile.

Raben's father, a prominent physician, was arrested as "the son of an enemy of the people" when she was 4 -- too young to remember the incident, but old enough to recall the taunts of her friends.

Once, she and her mother traveled about 500 miles north by train to visit him. Though she had not seen her father for five years, the rules allowed them only 10 minutes together. The rules did not allow kisses and hugs. "This I remember as if it was yesterday," Raben said last week. "Because of that trip, I do not feel at home in my country."

Her father was released in Khruschev's amnesty of 1954. By then she had learned something else: Being Jewish was not a thing you talked about at school.

"It is something uncomfortable, like you are crippled," Raben said. "You know you have to live with it the rest of your life. It is your hump."

Her 42 years as a Jew in the Soviet Union were enough to make her seek a different life. Her three months in the United States have made her think that she chose well.

Initially, she was struck by "the abundance," what she called "this terrible nightmare of choice" that seemed to assault her senses. Her first trip to the Safeway made her wonder, "What are they doing with all these products at the end of the day? They could not possibly sell them all." In Moscow, her husband said, shopping for food was "a forced safari" on trains and buses and into endless lines at stores, crisscrossing the city for an egg here, a piece of sausage there, a scrap for their shaggy, black poodle Filia.

Now they have learned to relish the choices, and their weekly trip to the Safeway "is like a holiday," Belenky said.

Sophisticated and intelligent, with many Western journalists as friends, Belenky and Raben have adjusted well to American life. Raben, a biochemist fluent in English, got a research job at the National Institutes of Health. Belenky, 46, who speaks French and English, is teaching part time at George Washington University.

They thought they knew what the United States would be like, but the depth of their new-found freedom has struck them in unexpected ways.

The U.S. Capitol would be open, they were told, but Raben had no idea she could sit and talk with aides to senators and representatives, as she did two weeks ago. "It is a miracle," she said.

A minor miracle, too, was their daily walk on Massachusetts Avenue NW when they arrived in Washington to stay with friends. "It was a big experience, especially for Filia," Belenky said, "to walk along the fence of the vice president's residence."

Recalling the "labor book" with her entire work history that she carried to any new position in Moscow, Raben took all her "documents," birth certificate and diplomas, when she reported for work at the NIH.

But when she arrived at the personnel office, no one asked her for a thing. Even the so-called green cards, issued to the family by the Immigration and Naturalization Service, contained no photos, Raben said. "That was very strange."

Surprising, too, was the ease with which they were welcomed into the Jewish community. Thrilled that they could practice their Judaism in public, Belenky checked the prospects of joining the Beth El Hebrew Congregation near their home. "I telephoned . . . and the rabbi's secretary asked my purpose," Belenky recalled. "I said, 'I want to be Jewish.' And she said, 'Okay, come over tonight.' "

Their 19-year-old daughter Masha was amazed at the realm of choices open to her. In Moscow, she said, "all the doors were closed for me, because I am Jewish and especially because I am a refusenik. If something happens and emigration stops, I thought, I would be a dead person. Now I feel I can do what I want. It all depends on me . . . . "

Belenky still marvels at what he calls the "abnormal normality of this life" in the United States. It seems all the more precious when he thinks of the risky road his family chose in 1979, at the height of Jewish emigration.

He and Raben applied for exit visas and prepared for what they call "life in refusal": losing their jobs, being branded "traitors" by their neighbors, getting visits from the police and sending Masha, who was then 10 years old, to a new school so her classmates would not know. And they prepared to wait.

"The mailbox became an animated person to us," Raben recalled. "We checked two times a day."

News, they learned from other refuseniks, came in a single sentence. "You are summoned to room --," the post card from the government read. If the blank was filled in with number 24, you were getting your visa. If it said room 22, you were not.

Two years and eight months later, Belenky said, "We got our first nyet. Then nyet came on a regular basis."

In 1986, Belenky and Raben, private people who had wanted only "to survive," got fed up with waiting in silence. They protested. They fasted. They gave interviews to foreign TV. Raben was arrested and fined 50 rubles for carrying "provocative slogans" in a demonstration. "I started calling her my little terrorist," Belenky joked.

It was at once frightening and exhilarating to challenge the Soviet system, he said, and Raben's sister Elena found it too frightening to try. "We were scared, too," Belenky said. "But you overcome your fears. It is a sort of euphoria . . . a feeling of liberation." It was also, they believed, the way to win their battle.

In April, Raben's parents -- who had applied, too, and planned to emigrate to Israel -- were granted their visas. Permission for Raben's family of three came a few days later. Officials had decided "to get rid of the troublemakers," Belenky said. It was only a matter of time, they thought, before Elena Raben was contacted, too.

But when the call came, Elena Raben was told her family's visa had been denied because her father-in-law, a retired engineer who had not sought a visa, once had access to state secrets. It was the first time in eight years that reason was used.

"It was a dirty trick," Nina Raben said. Visas are good only for 10 days, and by the time of Elena Raben's denial, things had moved too far for Nina Raben and her parents to turn back. Still, they wavered, but Elena Raben insisted that a sister in the United States could only help her cause. "Somebody must go," Nina Raben remembers her saying.

So the Belenkys packed up their lives in three crude cardboard suitcases -- books that Belenky had translated, copies of birth certificates and diplomas, a few pieces of clothing and prized family photos. They took 90 rubles each, about $390 -- the maximum allowed by law. Everything else they sold or gave away.

"During this time . . . belongings mean nothing," Nina Raben said. "You are so lucky to get the visa, you certainly wouldn't risk being detained. You could be detained for a day . . . . "

"Or forever," Masha Belenky finished her thought.

On May 6, they took off for Vienna.

They did not feel truly free, Belenky said, until they landed in Vienna and stepped off the plane. In some ways they are not free even today, haunted as they are by thoughts of Elena Raben.

They have talked with her only twice. Last week, they received their first letter from her, unsigned because it was smuggled out by a friend:

Dear Nanochka,

My emotional state is so bad that I cannot be your regular pen friend.

We are all alive. Vladimir works very hard because I am afraid he will be soon fired.

I really cannot write because I am crying all the time.

Probably next time it will be better, though I don't know when next time will be . . . .

My bedroom looks like a photo exhibition of mother, father, Masha and a portrait of you on the chest of drawers. Next to my bed is a photograph of all of us. How wonderful it was.