United Airlines Flight 585 was a scheduled passenger flight on March 3, 1991, from Denver to Colorado Springs, Colorado, carrying 20 passengers and 5 crew members on board. The plane experienced a rudder hardover while on final approach to runway 35 at Colorado Springs Municipal Airport, causing the plane to roll over and enter an uncontrolled dive. All 25 people on board were killed. The NTSB was initially unable to resolve the cause of the crash, but after similar accidents and incidents involving Boeing 737 aircraft, the crash was determined to be caused by a defect in the design of the 737's rudder power control unit. Aircraft and flight crew Flight 585 was operated by a Boeing 737-291, registered . The 737 was originally manufactured for the "old" Frontier Airlines in 1982 and was acquired by United Airlines in 1986 when the former went out of business (a new airline company with the same name formed eight years later). On the date of the accident, the aircraft had accumulated approximately 26,000 flight hours. The flight crew consisted of Captain Harold Green (52), First Officer Patricia Eidson (42), and 3 flight attendants. The captain, who had over 10,000 hours as a United Airlines pilot (including 1,732 hours on the Boeing 737), was regarded by colleagues as a conservative pilot who always followed standard operating procedures. The first officer had accumulated over 4,000 flight hours (including 1,077 hours on the Boeing 737), and she was considered by Captain Green to be a very competent pilot. On February 25, 1991, the aircraft was flying at 10,000 feet when the rudder abruptly deflected 10 degrees to the right. The crew on board reduced power and the aircraft returned to normal flight. A similar event occurred two days later. Four days later, the aircraft crashed. Accident Flight 585 was a regularly scheduled United Airlines Flight from General Wayne A. Downing Peoria International Airport in Peoria, Illinois to Colorado Springs, Colorado, making intermediate stops at Quad City International Airport in Moline, Illinois and the now-decommissioned Stapleton International Airport in Denver, Colorado. On March 3, 1991, the flight operated from Peoria to Denver without incident. At 09:23 AM Mountain Standard Time, Flight 585 departed Denver with 20 passengers and 5 crew members on board and was scheduled to arrive in Colorado Springs at 09:46 AM. At 09:37 AM, the aircraft was cleared for a visual approach to