On the basis of processing of results of theoretical, numerical and experimental work that describe supersonic flows of an ideal gas, the mechanism of formation of forces causing separation of these flows from a streamlined surface in the transient and spatial trends is formulated. A scenario is suggested for the separation of the-flow of gas from the surface of the body or the mixing layer in the form of a vortex, which induces a velocity in the field of flow, opposite to the velocity of the main flow, while also decelerating it. In the framework of the proposed scheme, the conditions of separation for cone and self-similar gas flows are analytically derived, which coincide with the results of experimental and numerical simulation.