The plane crashed.

There were no survivors.

The freak midair collision between a small plane and a helicopter killed the senator from Pennsylvania, the pilots, and two little girls who had been skipping in the schoolyard at recess when the flaming metal fell from the sky.

One moment, Teresa Heinz was puttering around her Georgetown home, waiting for her husband to call so that their youngest son could share the great news from the day's mail. He had been accepted to Yale, his father's alma mater. The next moment, that life was gone. At 51, she was a widow with three boys, the heiress to a $500 million fortune grown from pickles and ketchup, new leader of a philanthropic family and chief caretaker of its legacy.

Within days of the April 4, 1991, tragedy, she rejected calls for her to assume John Heinz's Senate seat. Instead, she was determined to take over the Heinz endowments, with combined assets of more than a billion dollars. They were headquartered in Pittsburgh, a once wealthy, enlightened city guided by the industrialist paternalism of the Carnegies and the Mellons and the Heinzes. By the mid-'80s, the region's big steel was dead, many of its workers unemployed and hurting, its slag heaps and brownfields scarring the original beauty of the hilly topography, its three rivers polluted.

She was decimated, personally, and "that place" -- her city -- "was decimated psychologically and economically. My job was to go home. That was my instinct," Heinz Kerry recalled in an interview aboard the campaign plane on Friday. She told herself, "I have to mother my kids, and I have to mother Pittsburgh."

Trained as an interpreter, fluent in five languages, a native of Mozambique who didn't become a doctor because she thought it would interfere with being a wife and mother, Heinz Kerry knew nothing of fiduciary responsibility or the machinations of charitable works. She had heart. She had intuition and intellect.

And she had a whisper of advice from her late husband: After his death, someone handed her a sheaf of singed and soggy notes in his handwriting. They had fluttered to earth from the wreckage.

The senator had been working on his plan for the Heinz foundations on the flight. His widow studied the notes, reflected on conversations they had during their 25-year marriage, drew on her own experience in founding a preschool and aiding Soviet Jews. Then, through the canyon of her grief, she began to reorganize the foundations according to his wishes.

Over the past 13 years, as the firm guiding force of the family philanthropy, Teresa Heinz Kerry has helped choose who gets the $50 million to $70 million the charities pass out each year to educational, environmental and cultural programs. She hands out the annual Heinz Awards, which bestow $250,000 on leaders and thinkers in those areas most important to John Heinz. She has a think tank in Washington. And, through her own personal philanthropies, she helped develop a prescription drug plan for senior citizens adopted by the commonwealth of Massachusetts.

Even now, on the eve of the Democratic National Convention, as she jets to campaign rallies and works on her Tuesday night speech, Heinz Kerry is huddling with her chief of staff, Jeffrey Lewis, going over analyses of similar drug blueprints for Rhode Island, Virginia and Idaho.

The very breadth of her work, and her very deep pockets, have caused some conservatives to question her influence and its potential for conflicts of interest should her husband of nine years, Sen. John Kerry, become president. Foundation officials and Heinz Kerry dismiss such concerns. She has said repeatedly that while she and Kerry talk about issues, she has never offered him advice about policy. And he has never set foot in the endowments' offices in Pittsburgh.

As she has molded the charities, so has the work molded her. She is a visionary, say those who have worked with her closely, but a highly pragmatic one. "I have grown confident," said Heinz Kerry, in her thinking and agenda. "I am not afraid of making mistakes. You can tinker," in life and in philanthropy, she suggested, and you can fail. "The value is to figure out why things do or do not work."

Once so grimy and gray, Pittsburgh now glistens by day and glitters by night, its spectacular skyline reflected in the water.

It has a vibrant arts and cultural district right downtown where the red-light district used to be, anchored by the historic Heinz Hall built by her late father-in-law for the Pittsburgh Symphony. There are two venues, the Byham and the Benedum, which rival Europe's finest opera halls for opulence. A new modern stage was designed by Michael Graves. The performance spaces and galleries have brought eclectic restaurants and a fledgling movement to convert some gorgeous old buildings into jazzy new condominiums.

Pushed by Heinz Kerry, Pittsburgh has become the most environmentally progressive city in the nation, proclaims its mayor, Tom Murphy, who has taken to calling her "St. Teresa."

Programs are underway to build residential housing on top of slag heaps and an island where a rendering plant once stood. A wide swath of open space will be landscaped with hiking trails and bicycle paths and perhaps a light rail line to link neighborhoods.

A new, 1.5 million-square-foot convention center swoops up over the Allegheny river. Unlike the dark box it replaced, the new center, clad mostly in white aluminum with a stainless steel roof, appears as if it might sail off upriver. Its halls are flooded with daylight; its thick cable supports are exposed throughout the halls, soaring toward the ceiling. With its water recycling systems and its energy-conserving skylights, it is the largest certified "green" building in the country.

The banks of the rivers have been purchased for incorporation into a city park that, including the water itself, will be the size of Central Park in New York. Native grasses have been planted along miles of former parking spaces, where people now stroll, bike and rollerblade. The city's two new stadiums sit behind the riverbanks, and open space is under development between them.

Heinz Kerry's thinking threads through all of the revitalization in this city of 338,000. She has remained true to the ideals of her late husband, an only child who headed the endowments for only four years, after the death of his father.

It was her idea to hold a design competition for the new convention center. She funded it, "and then she was out of it. She doesn't exercise her own eye," said Janet Sarbaugh, who heads the cultural programs of the endowments. The jury chose Rafael Vinoly, the architect for the Kennedy Center expansion. It was Heinz Kerry's idea to form a river life task force of public officials and private foundations and other civic leaders.

At a joint board meeting in 1999 of the two family endowments, during a discussion of urban design, Heinz Kerry jumped from her seat and went to the large windows of the offices, high above the Allegheny river. She was dismayed, gazing at a housing development across the river. It had all the visual appeal of a standard-issue La Quinta Inn.

"We have got to make sure that what happens on the riverfront isn't schlock," she said, recalls Maxwell King, the endowments' president, "so that it doesn't fill in in a haphazard, episodic and dysfunctional way. Because once it's filled in, there is no way we can come back and change it." Such was her passion and conviction, he said, "it was the only time the board spontaneously appropriated a million dollars," thereby launching a comprehensive waterfront plan.

Heinz Kerry held meetings and hosted a dinner at her family farm outside Pittsburgh, and through those many discussions a plan took shape.

"Teresa didn't invent the rivers, and she wasn't the first person to think about doing something on the rivers, but she applied that very creative and intense and elliptical thinking, always returning to the topic," said King, former editor of the Philadelphia Inquirer. "So that what finally resulted is a stark six or eight levels of quality higher than it would have been without her. And it ain't just the money; it's her mind."

Certainly, financially strapped city officials, arts and cultural leaders and endowment staffers would be loath to criticize a benefactress backed by billions. Those who work for and with her say Heinz Kerry is demanding and questioning, and they swear they love her for it. Presented with a proposal, Heinz Kerry will fire back a series of questions, "and that could be five to 50, and it may start on a Monday and finish on a Friday, and you may be writing and ginning up memo after memo, and we will be going back and forth," said Lewis, her chief of staff. "And it's interesting intellectually. This way, there is someone else challenging your thinking, which is the fun part, once you've done all your analysis." She will get out her calculator and start adding up numbers.

Heinz Kerry is, said William McDonough, an architect hired to collaborate on several foundation projects, "a humanist who can do math." She wanted him to use narra, a "non-extinct" rosewood, in his redesign of the foundation offices, but only if the price was competitive. The order, for $75,000 of the wood, jump-started the formation of a small company in San Francisco to find the material and deliver it. Then local cabinetmakers crafted with the narra, and their familiarity with it led in turn to other designers placing other orders.

"Teresa has this capacity to help people find their own strengths," said Grant Oliphant, who was press secretary to John Heinz and now is associate director at the foundations. "That's why she is so effective as a leader. I think it's why her friends call her 'Mama T.' She really pays attention to what people have to offer and tries to draw that out of them."

"She can be very strident about it, but she wants to nurture," said Doug Root, the endowments' communications officer.

When consensus has been reached, she gets out of the way.

"I don't mess with people," Heinz Kerry said. "I just want them to be accountable." She believes in newer "venture philanthropy," using the monies like venture capital, to incubate ideas. She does not believe in endlessly bailing out struggling institutions, which may have become dependent on the largesse of their wealthy supporters. "That annual giving has to stop," she insisted. The foundations have imposed outside experts on foundering groups as a condition of the grants.

The symphony learned the hard way whom it was dealing with when she bluntly refused the board's first request for $30 million for its new capital drive. The symphony had to cut costs, fix its long labor problems and increase its subscriptions. Then it got $20 million. Similarly, Heinz Kerry said, when the opera company was projecting costs over its agreed budget, its board cut one of its offerings that season to save the money, and, Heinz Kerry said, "we gave them a $150,000 prize check, as a reward for making the tough decision. We don't live in the era of the old habits." In 2002, the endowments were greeted with howls of protest when, along with two other groups, they withdrew $3 million in literacy funds they had put into the public schools.

There have been failures.

Impassioned about early-childhood development, Heinz Kerry spurred the foundations to provide educational programs for low-income preschoolers and raised money from other sources. But, after three years, the endowments pulled the plug. They had spent more than $30 million and served fewer than 700 students.

In keeping with Heinz Kerry's insistence on learning from mistakes, the endowments then commissioned two studies to determine what went wrong.

She is not the sort of rich woman who can move through Pittsburgh's cultural district, admiring the meticulously restored gilt on the historic theaters' proscenium arches, and not see the many homeless people panhandling on the sidewalks outside.

"One of my dreams is to bring real life back to downtown," she begins, and launches in a ruminative, discursive discussion of how to solidify the economic health of Pittsburgh's downtown by linking its residents more easily by water taxis. To listen to her idea in its entirety makes clear the thoroughness of her thought -- it has to do with supporting an emerging young middle class and growing a tax base. It also reveals how her mode of expression is hardly an easy fit for the highly scripted, strictly disciplined message delivery necessary in a presidential campaign. (Even her name is conflicted. In the campaign, she is known as Heinz Kerry; at the endowments, she is Mrs. Heinz.)

Her visions are at once lofty and practical; she is animated when she talks about them. Her eyes flash; her hands swirl through the air. Leaning forward in her airplane seat Friday, her face lit up as she remembered seeing two egrets along the river, and the discovery of a clam "this big!" -- she spread her fingers wide -- where the Allegheny and Ohio join, sure signs of returning water quality.

And, "It is wonderful to see kids make friends with the water," she said, in a city where parents always warned their children, "Don't go down to the river." She wants to expand rowing programs to reach disadvantaged children. "It's such a demanding sport, and can you imagine someday a U.S. boat [competing] with African Americans and Indian and every other ethnic group? Wouldn't that be wonderful? It would look like America! Rather than just these skinny white kids?"

Asked what made her proudest about her work, she said, "Mostly, I feel proudest of the commitment of people to believe."

"In the early years," she said, "I would go once a week and meet with every chief [grantmaking officer], and I would ask them: 'What are your dreams? What stands in the way? Dream!' "

A conservative think tank, the Capital Research Center, has published research that charges the Heinz endowments with funding environmental organizations that "pay for groups sponsoring thinly disguised anti-business drives and partisan political campaigns."

Oliphant calls the allegations "ridiculous" and unfounded, noting the centrist nature of the Heinz family's values -- John Heinz was a Republican. King points out that all philanthropic groups are forbidden from funding political advocacy, and that any grant monies disbursed can flow only into the specific project funded, not an organization's general budget.

"People are usually talking about conflict of interest, and where that usually gets murky and dark and worrisome is in areas where people might personally profit from their official roles," said Oliphant. "We're talking about giving away money here. We're talking about charity! We are buttoned up to a T on every one of our practices, and Teresa subscribes to that as much as any of us; she's been the author of much of it."

What is clear is that there is no precedent for such a powerful woman to rise to the position of first lady. Eleanor Roosevelt created an independent portfolio once she was in the White House, mused King, but "Teresa would bring it in with her."

Having fought to make the transition from being a fairly traditional and shy woman to being secure in her own influence and opinions, Heinz Kerry is disinclined to give up her job. The lawyers have scrutinized her relationships to the endowments -- she chairs one, serves on the board of another, and heads the family philanthropies based in Washington -- and declared there is no conflict.

But demands on her time and the tortured expectations for the proper deportment of a first lady might conspire against her. In her work, her counsel and creativity are prized. In the campaign, they can be a liability.

Asked how she would manage in both roles, she said, "I don't know how I would do it because I have never been here before.

"Normally, it is: 'What's going to be your cause?' I don't have a cause. My cause is a better quality of life -- stronger, healthier, more self-sufficient -- more able to be whole." Throughout the nearly unimaginable drama of her 65 years, she seems to have accomplished this wholeness for herself. And now she is dreaming she might extend it to everybody else.

"I have to mother my kids," Teresa Heinz Kerry says, "and I have to mother Pittsburgh," home to the Heinz philanthropies. Heinz Kerry reorganized the endowments according to her late husband's wishes.Rep. H. John Heinz III got a kiss from wife Teresa during his successful campaign for the U.S. Senate in 1976. Above, Teresa being escorted by sons H. John IV, left, Andre, second from right, and Christopher at the senator's funeral in 1991. Heinz died in a plane crash.Teresa Heinz Kerry funded the design competition for Pittsburgh's new convention center, above, which graces a city whose cultural riches include the opulent Byham Theater. Left, she confers with officials at a youth development center founded by the Heinz family in 1901.The Kerrys at a campaign stop earlier this month in Beckley, W.Va.