An error in judgment during what should have been a routine flight in April 1991 took the lives of seven, including a senator at the height of his political career.

Sen. H. John Heinz III was on his way from a news conference in Williamsport, Lycoming County, to Philadelphia when the Piper Aerostar he was flying on collided with a Bell 412SP helicopter, causing both to crash into the grounds of Merion Elementary in Lower Merion, Montgomery County.

Shortly before the crash, the pilots had radioed that the landing gear light had not come on. The helicopter was nearby and tried to get close enough to see if the landing gear was down when the two aircraft collided.

The investigation blamed the crash on poor judgment by the pilots of both the plane and the helicopter, noting that the helicopter wouldn't have been able to see whether the landing gear was locked.

All three aboard the airplane and both aboard the helicopter were killed, as were two students at the school.

Heinz, the heir to the H.J. Heinz Company, was 20 years into a political career and almost halfway through his third term in the U.S. Senate. He was 52.

Hundreds of U.S. senators and representatives have died while serving in office. Many died from heart disease, stroke, cancer or some kind of contagious illness.

Heinz is one of about 20 members of Congress to die in a plane crash, though.

The first sitting member of Congress to die in an aviation accident came about 25 years after the Wright Brother's successful flight over Kitty Hawk, N.C., in 1903. Thaddeus Sweet, a representative from New York, was killed in May 1928 when he unbuckled his seatbelt during a bumpy landing and hit his head.

About 18 months later Rep. William Kaynor from Massachusetts was killed when the plane he was flying in crashed — it was his first time in an airplane.

The death of the first sitting senator in a plane crash would lead to reform. Sen. Bronson Cutting, R-N.M., was killed when the Douglas DC-2 he was a passenger on crashed.

The investigation and subsequent U.S. Senate committee uncovered problems with air traffic control standards, enforcement of regulations and more.

Only one sitting senator has died in a plane crash since Heinz. Sen. Paul Wellstone, D-Minn., was killed in October 2002 when the Beechcraft Kind Air A100 he was flying on crashed near Eveleth, Minn.

As was the case with the crash that killed Heinz, the investigation found the likely cause to be an error in judgment by the pilot.

Heinz's death came almost 70 years after the last time a sitting senator from Pennsylvania died. In fact, 1921 and 1922 saw the death of three sitting senators from the state.

Philander Knox served two terms in the U.S. Senate. He was appointed in 1905 after the death of Sen. Matthew Quay and served until 1909, when he was named U.S. Secretary of State.

In 1916, he became the first senator in Pennsylvania elected by popular vote, following the 17th Amendment's adoption in 1913. He died in October 1921.

Just months later, on New Year's Eve 1921, Boies Penrose, the senior senator from Pennsylvania, also died.

And in August 1922, William Crow, who had been appointed to succeed Knox, also died in office.

At the time of his death, Heinz had spent almost exactly 20 years in elected office.

After graduating from Yale University in 1960 and Harvard Business School in 1963, Heinz served several years in the U.S. Air Force Reserve, worked in finance and marketing at H.J. Heinz Company and taught business at Carnegie Mellon University.

In 1971, he ran as a Republican and won a special election to fill the seat of U.S. Rep. Robert Corbett, who had died in office. Heinz went on to win reelection the next year and again in 1974.

In 1976, he ran for U.S. Senate and won. The election marked a first: The first time a Republican had carried every ward in Pittsburgh.

Tributes to Heinz, from both before and after his death, emphasize his willingness to work with anyone, regardless of political party, as well as his deep drive to improve the country and the world.

“In the performance of his duties, both as a public servant and as a philanthropist, he was not merely tireless, he was joyfully ferocious, himself the embodiment of radiant living,” Teresa Heinz Kerry said in a biography of her late husband created by the Senator John Heinz Pittsburgh Regional History Center.

He would win reelection in 1982 and 1988. During his 15 years in the Senate he served on the Committee on Banking, Housing, and Urban Affairs; the Finance Committee; as chairman of the Subcommittee on International Finance and Monetary Policies; as chairman of the Special Committee on Aging; as chairman of the Republican Conference Task Force on Job Training and Education; National Commission on Social Security Reform, and the National Commission on Health Care Reform; the Northeast Coalition and the Steel Caucus.

In the more than 30 years since Heinz's death, his legacy of philanthropy has continued to grow, with multiple institutions carrying his name. Some of them include the Senator H. John Heinz III Archives at the Carnegie Mellon University Libraries; the H. John Heinz III College at CMU; the H. John Heinz III Center for Science, Economics and the Environment; the Heinz History Center and the H.J. Heinz Campus of the VA Pittsburgh Healthcare System.

In addition to that, the American Institute for Public Service named one of its Jefferson Awards in Heinz's honor. Each year, the Jefferson Awards include the U.S. Senator John Heinz Award for Outstanding Public Service By An Elected or Appointed Official.

“Publicly elected or appointed officials carry the greatest responsibility to serve the need of the American people, and to offer unusual leadership,” the Jefferson Awards website explains. “By elevating the national standard of what it means to serve in public office, more qualified young people will aspire to civic leadership.”

At his funeral in April 1991, Heinz was honored for his dedication to both his office and for his desire to change the country for the better.

Democrat Sen. Tim Wirth, of Colorado, was a longtime friend of Heinz's and spoke at his funeral.

“He really believed he could make the world a better place, such a contrast to the jaded resignation of our time,” Wirth said.

Another friend, Heinz's college roommate, Theodore Stebbins, the longtime curator at Boston's Museum of Fine Arts, echoed the idea of Heinz's idealism.

“All men are dust,” Stebbins said during his eulogy. “But some men are dust of gold.”