On July 19 , 1989 , United Airlines Flight 232 , a McDonnell Douglas DC-10-10 , experienced an uncontained failure of its No. 2 engine stage 1 fan rotor disk assembly . The engine fragments severed the No. 1 and No. 3 hydraulic system lines . Forces from the engine failure fractured the No. 2 hydraulic system line . With the loss of all three hydraulic-powered flight control systems , safe landing was impossible . The lack of independence of the three hydraulic systems , although physically isolated , left them vulnerable to a single failure event due to their close proximity to one another . This was a zonal hazard . The aircraft crashed after diversion to Sioux Gateway Airport in Sioux City , Iowa , with 111 fatalities , 47 serious injuries and 125 minor injuries
United Airlines Flight 232
United Airlines Flight 232
Zonal safety analysis