Disclosed is a dynamic fault tree analysis system including a fault tree module associated with a mission critical system (mcs), wherein said fault tree module includes at least one item characterized by an initial probability density function (pdf), at least one threshold value associated with the mcs, a sampling module to transform the initial pdf to a heterogeneous pdf (hpdf), wherein the hpdf includes at least one continuous segment and at least one discrete segment, and wherein transition between segments is at least partially based on the at least one threshold; and a stochastic simulator to determine the probability of an mcs failure condition by analyzing the fault tree module using the heterogeneous pdf.