As with the Eastern Air Lines Flight 401 crash of a similarly-sized Lockheed L-1011 in 1972 , the relatively shallow angle of descent likely played a large part in the relatively high survival rate . The National Transportation Safety Board concluded that under the circumstances , " a safe landing was virtually impossible . " The odds against all three hydraulic systems failing simultaneously had previously been calculated as low as a billion to one . Yet such calculations assume that multiple failures must have independent causes , an unrealistic assumption , and similar flight control failures have indeed occurred : The disintegration of a turbine disc , leading to loss of control , was a direct cause of two major aircraft disasters in Poland :
Eastern Air Lines Flight 401
Eastern Air Lines Flight 401
United Airlines Flight 232