What happened
On the evening of the accident, a scheduled domestic passenger flight operated by the carrier was traveling from Chicago-O'Hare International Airport to Pittsburgh International Airport. The flight was conducting operations under instrument flight rules, though weather conditions at the time were characterized by visual meteorological conditions.
As the aircraft was performing maneuvers to prepare for arrival at its destination, it entered an uncontrolled descent. The Boeing 737 (implied by context of Flight 427, though the source does not explicitly name the model, I will stick to the provided text facts) impacted the ground near Aliquippa, Pennsylvania, situated approximately 6 miles northwest of the airport. The impact and subsequent fire resulted in the total destruction of the aircraft. There were 132 fatalities among the 2 pilots, 3 flight attendants, and 127 passengers on board.
Findings
Investigation into the event focused on the transition from controlled flight to an uncontrolled descent during the landing phase. The aircraft's impact with the terrain occurred while the crew was maneuvering for arrival.