The Merion air disaster occurred in southeastern Pennsylvania on April 4, 1991, when a Piper Aerostar propeller-driven aircraft collided in mid-air with a Bell 412 helicopter over Merion Elementary School in Lower Merion Township, a suburb northwest of Philadelphia. All five people in both aircraft were killed, including United States Senator John Heinz, the sole passenger of the Piper.^[2] Two schoolchildren on the ground were killed by falling debris. In addition to the seven total fatalities, five more people on the ground were injured.^[1]

An investigation determined the cause of the accident to be poor judgment and pilot error of the crews from both aircraft.^[1]

John Heinz's aircraft departed from Williamsport Regional Airport (IPT) in central Pennsylvania on the morning of April 4, 1991, at about 10:22 a.m. EST.^[1] Heinz was in Williamsport for a press conference pertaining to federal funding of U.S. Route 15.^[3] Heinz rented the twin-engine Piper Aerostar from Lycoming Air, based at the Williamsport airport. Heinz and his two pilots, both from Lycoming County, departed for Philadelphia International Airport (PHL) slightly before 10:30 a.m.

As Heinz's aircraft made its approach to Philadelphia International Airport at approximately 12:01 p.m., the crew noticed that the nose landing gear "locked" indicator was not illuminated.^[1] The crew began troubleshooting the problem and alerted air traffic control. Approximately three minutes later, the plane executed a low pass near the tower; the controller reported to the crew that the nose gear appeared to be extended.^[1]

The crew of a passing Bell 412 helicopter, operated by Sun Company Inc. and headed to the company's headquarters in Radnor, Pennsylvania, offered to take a closer look to see if the gear was indeed down and locked.^[1] They moved near the Aerostar for a better look, and the final transmission from the helicopter crew was to advise the Aerostar crew that "everything looks good from here."^[1]

At 12:10 p.m., the two aircraft collided over Merion Elementary in Lower Merion, with the helicopter's rotor blades clipping the Aerostar from underneath. The helicopter spun out of control and the Aerostar dived to the ground, disintegrating on impact in the elementary school grounds. All five people on board both aircraft were killed, including Heinz. Two schoolgirls were killed and five others injured by the debris, which fell in a 250-yard (230 m) radius around the school and surrounding area.^[4]

A National Transportation Safety Board (NTSB) investigation was opened almost immediately.^[5] In September 1991, the NTSB's finding were announced. It was determined that the poor judgment of both flight crews caused the accident.^[6][7][8]

The NTSB report stated that visual checks of the aircraft from the helicopter were pointless because it is virtually impossible to see into the nose-wheel well of an Aerostar to determine whether the nose gear is locked.^[1] Further, with the nose gear physically in the down position, a more experienced pilot probably would have attempted a landing "accepting the possibility that the nose gear could collapse during the landing roll", as such a condition "does not generally result in a major accident or occupant injury."^[1] Investigators cited a litany of mistakes and wrong decisions that led to the deaths and injuries. "This was a senseless accident that didn't have to happen," said James L. Kolstad, then-chairman of the NTSB.^[9]

The accident caused a change in procedure at many airports, as helicopters were not to be used to inspect potential landing gear failures; aircraft should only fly a low pass near the airport for visual confirmation from services on the ground.^{[citation needed]}

Word of Heinz's death came from his Washington office. At midafternoon, sobbing members of his staff began walking out of his office in the Russell Senate Office Building. A few minutes later, the senator's legislative director, Richard Bryers, announced Heinz's death to reporters.^[10]

News of Heinz's death at age 52 shocked fellow lawmakers:

• Senator Tim Wirth of Colorado stated that he and his wife, Wren, considered Heinz and his wife, Teresa, "our dearest friends in the Senate," and paid tribute to his "intense intelligence, sparkling charm, and broad vision."^[11]
• Senate Minority Leader Bob Dole of Kansas called Heinz "a dynamic and dedicated public servant, a tireless champion for Pennsylvania and a good and decent family man."^[12]
• Vice President Dan Quayle, in Los Angeles for a speech, said that "we are going to miss John Heinz tremendously. He made a tremendous contribution to the U.S. Senate."^[13]

The crash received multi-national attention, with reports appearing in multiple regions including the United Kingdom, France, Germany, Canada, and Australia.^[14][15] Flights over Merion Elementary School during school hours were informally banned for a period of time, and media avoided flying news or traffic helicopters over the school.^[16]

Heinz's funeral was held in Pittsburgh,^[17] and a memorial service in Washington was attended by President George H. W. Bush and Vice President Quayle.^[18]

On the 25th anniversary of the crash, in 2016, most family members of the schoolchildren at Merion Elementary School declined to be interviewed, although one did comment, "No one could have stopped this from happening. It was an act of God."^[16]