In this paper, the closed-loop human-machine system is studied under the framework of the control systems theory. The human operator model is considered concerning the human's ability for adaptation to the current operational conditions. For flying vehicles this property corresponds the crossover model by McRuer. In the paper, the actuator is modeled in the form of a first-order low-pass filter with the saturation. The paper deals with the case when the human operator manually controls the vehicle along one angular coordinate. In the paper, an algorithm for identifying the parameters of a human operator in a nonlinear control system is proposed. The implementation of the algorithm is based on solving a nonlinear optimization problem with restrictions on frequency characteristics, the range of possible values of the operator's model, and performance criteria for controlling a closed man-machine system. The proposed algorithm is illustrated by a numerical example, for which the human model parameters values are found by the example of the unmanned aerial vehicle's human control. For comparison, the parameters of the human operator model for a linear system are given.