All the people around her were calmly reading magazines or otherwise relaxing in their seats, awaiting takeoff. But Tierra Ford just trembled. This was to be her first plane ride, and when the jet landed 17 hours later, she would be 6,800 miles from her D.C. home -- in Tokyo.

Ford, 17, was excited, too. Leaving the tiny Southeast apartment she shared with her mother and six brothers and sisters, she soon would live the life of a Japanese teen-ager -- eating raw fish with new Oriental friends and taking public baths by the sea.

Ford recently returned to the District with, she says, a surprise for herself and her family: She is a more confident and independent young woman after the experiences of the year that followed that long flight.

She and seven other high school students were the first D.C. participants in a project called Youth for Understanding (YFU), designed to promote cultural exchange by bringing foreign students to the United States and sending American youngsters abroad. That was last summer.

"It definitely was one of the best experiences of my life. You learn about another country, but even more important, you learn so much about yourself and what you need to be happy," Ford says.

Youth for Understanding has been in operation since 1951 when the State Department provided money to start a program to foster interest in foreign cultures following World War II. Now operating in 23 countries, YFU has offices in 20 U.S. cities and is funded primarily by student program fees.

The project began its second year here last June with the dpearture of 26 D.C. youths for 13 foreign countreis. Five students from Denmark, Sweden, Mexico, Spain and Iran recently returned home after living and going to school here as part of YFU's one-year exchange program, also new.

The first group of Americans, recently returned, say they consider themselves lucky to have lived and traveled abroad while still in high school.

"I used to lie awake at night wondering about life in other countries," says Ford, a quiet, thoughtful young woman. "I'd think about the Japanese women in kimonos or the Eskimos in their handsome parkas. Then one day I decided I would go abroad. Nine months later I was on the plane to Tokyo."

Participants who have returned say the exchange program is especially exciting for those who have not traveled even within the United States.

"I've seen so many kids my age sitting on the pavement smoking dope in the summer. They're just vegging out, not seeing what they can do," says Frank Brevard, who lived in West Germany last summer and graduated in June from Ballou High School. "I didn't know what it meant to challenge myself until I went overseas."

Karen Priestly, a recent Coolidge High graduate who also went to Japan, agrees: "When you're getting ready to graduate, I think you need to get out of the house. You need to have an experience that shows you there is life out of D.C. Many kids here don't realize that."

Those who have gone overseas say emotional strength and humility are necessary ingredients in the recipe for a successful experience.

Language or cultural barriers can turn pleasant dinner conversations into argumentative nightmares when a word is accidentally mispronounced. Priestly recalls a stilted conversation she had with her new "sister" during her first week in Japan. A combination of mispronounced words and poorly constructed sentences turned Priestly's simple "thank you" into "You're ugly."

"Things get distorted; meanings of words get confused. Soon you realize the best way to send a warm message to a foreigner is just to smile. That's all. Keep your mouth quiet and look happy," said Priestly.

At orientation meetings before their departure, the youngsters are advised to "try everything" in their new homes. If not for that advice, Brevard says, he never would have sampled German foods he came to savor -- dark beer, steak-like meats or heavy bread.

Priestly says she would not have forced herself to enter the dirty, crowded public restrooms, and Ford says she never would have ventured into the public baths that are popular throughout Japan.

She says she remebers every detail of her first experience in the baths, which are shared by members of both sexes.

"I saw all these men and women going into the building but I figured once inside, we'd be split up," said Priestly. "I was shocked when I walked out naked and there were men there, just bathing away. I tried to cover myself up. But there was nothing I could do. I was so embarrassed."

What her mother had taught about tolerance paid off in Japan when her exchange brother gave her a big black bug as a going-away present. "I was excited by the present, but more from terror than thanks. Then I thought about how important that bug had been to my brother, and I just cried with happiness. He was giving away his favorite jewel."

The students, all black, said they encountered no racial prejudice while overseas.

"You come to think prejudice is an American syndrome. I didn't find anything like that in Japan," says Priestly, who lived both in the Tokyo suburbs and in Utsunomiya, a city of 300,000 60 miles north of Tokyo where blacks live among native Japanese.

The students, six of whom were on partial or full YFU scholarships, learned of the program in their high school language classes. YFU area representatives, who want to expand the District program, show slides and movies of foreign countries both to attract students interested in going abroad and to find District host families for foreign students.

Since their return nearly a year ago, the students have helped YFU personnel give the presentations in all District high schools.

Participants pick the countries they want to visit, then YFU places them, matching the interests of the students with those of the host families.

Most of the District youths received full scholarship from YFU or area businesses, depending on their need.

To Tierra Ford, whose family could not have afforded the $1,500 program fee, the scholarship plan was essential to her participation.

Said Ford, "In D.C. that's the way to get to the kids. As soon as they think they have to pay, they stop listening.

"It's such a beautiful program, she continued, tears welling in her eyes. "It's nice a few kids from here are getting experience. It will shape their lives forever."