The article is dedicated to the problem of justification of dynamic loads on NPP process equipment, caused by aircraft impact. Usually these loads are set by means of floor response spectra (FRS). Nowadays, a conservative deterministic approach is used in practice, when the maximum possible FRS is taken in NPP process equipment design. Since aircraft crash on NPP is an extremely rare random event, it is necessary to use the probabilistic approach to analyze dynamic loads on NPP equipment. The method of FRS calculation with the required non-exceedance probability is given. The following random variables are considered: point and angle of aircraft impact, distance between point of impact and equipment support. Probabilistic justification of dynamic loads on NPP equipment caused by intentional aircraft crash (act of terrorism) is presented. The procedure for summing the corresponding internal forces, calculated using three components of FRS, is given. The criterion of the optimal step for integrating the equations of motion when calculating the forced oscillations of structures under aircraft impact is determined.