United Airlines Flight 553 was a scheduled domestic flight from Indianapolis International Airport to Chicago Midway International Airport. On December 8, 1972, the aircraft, a McDonnell Douglas DC-8, crashed while attempting to land in Chicago due to pilot error and poor weather conditions. The accident resulted in the deaths of 45 people on board, with only 2 survivors. It was one of the deadliest aviation accidents in the United States at that time and led to increased scrutiny of pilot training and safety regulations in the airline industry.