The work offers a mathematical model of “operator – vehicle – ambient conditions” system functioning. The model gives opportunity to define the quantitative estimation criteria of aircraft crew training. The model contains some evident simplifications, especially from the point of view of considering psycho physiological aspects of human activity, but it gives the opportunity to correlate the latter with a technical part of the considered system in unified coordinates. A definite kind of model depends on a definite functional task of an operator, or crew member. In order to describe the training process and estimate the operator’s performance on simulators a probability model of the considered ergatic system reliability is offered.