Abstract: Apparatus for digitally displaying inclination of a lift truck mast includes an inertial inclination sensor carried by the mast and a digital display module for operator viewing remote from the mast. The inclination sensor includes a disc pendulum pivoted for damping its movement, the disc having a wand extending from it for exaggerated movement about the pivot. A plurality of light responsive devices are provided for detecting the position of the wand for the purpose of determining the degrees of actual mast inclination with respect to a true vertical gravitational plumb line.