A one-dimensional ascending steady flow of a mixture of air, water, and solids in a vertical lift lift pipe is considered. As a physical model, this three-phase flow is represented as the compatible movement of the pulp (a mixture of liquid and solid particles) and compressed air in the form of shells. It is assumed that the lifting of solid material is carried out by liquid plugs that move in the intervals between the air shells. The purpose of the work is to determine the actual concentrations and velocities of the phases as one of the important hydrodynamic characteristics of the flow. The method of statistical averaging of these characteristics is used, similar to the theoretical-probabilistic method of averaging in the theory of turbulence, the basis of which is the transition from consideration of a single flow to consideration of a statistical set of similar flows carried out under almost identical conditions. The actual phase concentrations in any given live current section are considered in terms of the unconditional probability of one or another phase passing through the section. To determine the true velocities of the phases, hydraulic continuity equations are used, containing probability-averaged hydrodynamic quantities and describing each phase individually as some continuum in the statistical sense. In this case, the true velocity of a phase in any given live section is defined as the statistical average of the velocity, provided that this phase clearly intersects the section. The expressions obtained for the real concentrations and velocities of the phases form the theoretical basis for the construction of a hydraulic mathematical model of the three-phase flow with respect to the problem of airlift calculation.