United Airlines Flight 232 was a regularly scheduled United Airlines flight from Stapleton International Airport in Denver to O'Hare International Airport in Chicago, continuing to Philadelphia International Airport. On July 19, 1989, the DC-10 (registered as N1819U) serving the flight crash-landed at Sioux City, Iowa, after suffering a catastrophic failure of its tail-mounted engine due to an unnoticed manufacturing defect in the engine's fan disk, which led to the loss of many flight controls. Of the 296 passengers and crew on board, 112 died during the accident, while 184 people survived. Despite the deaths, the accident is considered a prime example of successful crew resource management because of the large number of survivors and the manner in which the flight crew handled the emergency and landed the airplane without conventional control. It is also the deadliest accident in the history of United Airlines.