USAir Flight 427 crashed on approach to Pittsburgh International Airport, resulting in 132 deaths and the longest accident investigation in the history of the National Transportation Safety Board.

USAir Flight 427 was a scheduled flight from Chicago's O'Hare International Airport to Palm Beach International Airport, Florida, with a stopover at Pittsburgh International Airport. On Thursday, September 8, 1994, the Boeing 737-3B7 flying this route crashed in Hopewell Township, Pennsylvania while approaching Runway 28R at Pittsburgh, which was USAir's largest hub at the time.

Pittsburgh International Airport —originally Greater Pittsburgh Airport and later Greater Pittsburgh International Airport—is a civil-military international airport in Findlay Township and Moon Township, Pennsylvania, United States. About 10 miles (15 km) west of downtown Pittsburgh, it is the primary international airport serving the Greater Pittsburgh Region as well as adjacent areas in West Virginia and Ohio. The airport is owned and operated by the Allegheny County Airport Authority and offers passenger flights to destinations throughout North America, Central America, and Europe. PIT has four runways and covers 10,000 acres (40 km²). PIT is the largest civil/public airport in terms of land area in the state of Pennsylvania.

The National Transportation Safety Board (NTSB) is an independent U.S. government investigative agency responsible for civil transportation accident investigation. In this role, the NTSB investigates and reports on aviation accidents and incidents, certain types of highway crashes, ship and marine accidents, pipeline incidents, bridge failures, and railroad accidents. The NTSB is also in charge of investigating cases of hazardous materials releases that occur during transportation. The agency is based in Washington, D.C. It has three regional offices, located in Anchorage, Alaska; Aurora, Colorado; and Federal Way, Washington. The agency also operated a national training center at its Ashburn facility.