A Eurocopter AS350 Écureuil and Piper PA-32R collide over the Hudson River, killing nine people.

The Airbus Helicopters H125, previously the Eurocopter AS350 Écureuil, or Squirrel, is a single-engine light utility helicopter designed and originally manufactured by the French corporation Aérospatiale, and later by Eurocopter, now Airbus Helicopters. In North America, the H125 is marketed as the AStar. The AS355 Ecureuil 2 is a twin-engine variant, marketed in North America as the TwinStar.

The Piper PA-32R is a six-seat, high-performance, single engine, all-metal, fixed-wing aircraft produced by Piper Aircraft of Vero Beach, Florida. The design began life as the Piper Lance, a retractable-gear version of the Piper Cherokee Six. Later models became known by the designation Piper Saratoga. The primary difference between the Lance and early Saratoga is the development of a tapered wing on the Saratoga, replacing the "Hershey bar" wing on the Lance that was a carryover from the Cherokee Six. Later Saratoga models provided updated/improved avionics, engine and interior touches but retained the same airframe design.

On August 8, 2009, at 11:53 a.m. (15:53 UTC), nine people died when a tour helicopter and a small private airplane collided over the Hudson River near Frank Sinatra Park in Hoboken, New Jersey, United States. The aircraft were in an area known as the "Hudson River VFR Corridor", which extends from the surface of the river to altitudes of 800 to 1,500 ft at various locations along the Hudson River in the immediate area of New York City. Within this corridor, aircraft operate under visual flight rules (VFR), under which the responsibility to see and avoid other air traffic rests with the individual pilots rather than with the air traffic controller (ATC).

The Hudson River, historically the North River, is a 315-mile (507 km) river that flows from north to south largely through eastern New York state. It originates in the Adirondack Mountains at Henderson Lake in the town of Newcomb, and flows south to the New York Bay, a tidal estuary between New York and Jersey City, before draining into the Atlantic Ocean. The river marks boundaries between several New York counties and the eastern border between the U.S. states of New York and New Jersey. The lower half of the river is a tidal estuary, deeper than the body of water into which it flows, occupying the Hudson Fjord, an inlet that formed during the most recent period of North American glaciation, estimated at 26,000 to 13,300 years ago. Even as far north as the city of Troy, the flow of the river changes direction with the tides.