Methods for identifying the dynamic characteristics of systems in the process of testing make it possible to obtain the most complete knowledge about the tested object, however, its practical application, as a rule, is limited to estimates of the characteristics of stationary systems under the influence of stationarydisturbances. The most common basis for identification methods are various types of solutions to the Wiener-Hopf equation.In order to develop methods for assessing the dynamic characteristics of missiles as control objects, a generalized solution of the Wiener-Hopf equation in the region of a complex variable for the case of non-stationary systems under the action of quasi-stationary disturbances is obtained. For this, the basicprovisions of the theory of systems optimal in terms of the minimum mean-square error and the spectral-correlation theory of nonstationary processes are used.In accordance with the developed algorithms and the computational program, statistical processing of the results of telemeasurements of control processes during the launch of several dozen missiles was carried out and estimates of the amplitude-phase frequency characteristics of the rocket were calculated, which made it possible to refine the parameters of the rocket's dynamic scheme and estimate the real margins of fl ight stability.