PCSTABL 6 is a computer program for the general solution of slope stability problems by two-dimensional limiting equilibrium methods and includes the analysis of reinforced soil slopes with geosynthetics, nailing, and tiebacks. The calculation of the factor of safety against instability of a slope is performed by the simplified Bishop method, applicable to circular shaped failure surfaces, the simplified Janbu method, applicable to failure surfaces of general shape, and the Spencer method, applicable to any type of surface. The simplified Janbu method has an option to use a correction factor, developed by Janbu, which can be applied to the factor of safety to reduce the conservatism produced by the assumption of no interslice forces. It features random techniques for generation of potential failure surfaces for subsequent determination of the more critical surfaces and their corresponding factors of safety. One technique generates circular; another, surfaces of sliding block character, and a third, more general irregular surfaces of random shape. The means for defining a specific trial failure surface and analysing it is also provided. Handles the following: heterogeneous soil systems, anisotropic soil strength properties, excess pore water pressure due to shear, static ground water and surface water, pseudo-static earthquake loading, surcharge boundary loading, tieback loading, soil nailing, and reinforced soil slopes. The tieback loading feature provides for the input of horizontal or near horizontal tieback or line loads for analysing the overall stability of tied-back or braced slopes and retaining walls. Plotted output is direct from the program to any printer or to HP jet printers using the provided Plotstbl program.