How to Create a Best Fit Path Along a Surface at a Given Slope

The Generate Grade Contour command computes and displays a path that traverses a triangulated Digital Terrain Model (DTM), ascending as steeply as possible without exceeding a specified maximum slope. The input for the command is an initial point, an initial direction, and a maximum allowable slope. The computed path terminates at the boundary of the DTM or at one of its local maxima. The path is further constrained not to exceed a specified maximum length.

This command is available as an Application Add-In.  To add the command, go to Tools > Application Add-Ins and toggle on "Generate Grade Contour Add-In".  The command itself can then be accessed in Surface > Utilities > Generate Grade Contour.