1991 Merion mid-air collision

On April 4, 1991, 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 west of Philadelphia, in southeast Pennsylvania. All five people in both aircraft were killed, including United States Senator John Heinz, the sole passenger of the Piper. On the ground, two schoolchildren were killed by falling debris and five people were injured.

An investigation determined the accident was caused by poor crew judgment and pilot error in both aircraft.

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. Heinz was in Williamsport for a press conference pertaining to federal funding of U.S. Route 15. Heinz hired a twin-engine Piper PA-60-601 Aerostar from Lycoming Air Services, an air taxi operator 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 pilots noticed that the nose landing gear "locked" indicator light was not illuminated. The crew began troubleshooting the problem and alerted air traffic control (ATC). A pilot in the Piper told ATC he could see the apparently extended nose gear reflected in the propeller spinners. 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.

The crew of a passing Bell 412SP 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. 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".

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, severing a main rotor blade of the helicopter and a main wing panel of the airplane and rendering both aircraft uncontrollable. The helicopter spun out of control and the Aerostar dived to the ground; both caught fire and disintegrated on impact in the elementary school grounds, while children were playing outside during their lunch recess. The Aerostar fell in the school yard near the entrance loop while the Bell fell behind the school building; debris also fell on nearby private residences in a 250-yard (230 m) radius around the school. The collision killed all five people on both aircraft, including Heinz. On the ground, two schoolgirls were killed, and five other persons were injured by fire and debris. Post-crash fires destroyed much of the aircraft wreckage and some landscaping at the school.

A National Transportation Safety Board (NTSB) investigation was opened almost immediately. 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.

In September 1991, the NTSB's finding were announced. It was determined that the poor judgment of both flight crews caused the accident.