A method of detecting a support structure in a navigational controller includes: controlling a depth sensor to capture a plurality of depth measurements corresponding to an area containing the support structure on a ground plane; generating, for each of the depth measurements, a projected depth measurement on the ground plane; selecting a boundary set of the projected depth measurements defining a boundary of the projection; selecting, based on angles between adjacent pairs of the boundary set of projected depth measurements, a subset of the projected depth measurements; generating a region of interest based on the subset of the projected depth measurements; retrieving a candidate subset of the depth measurements corresponding to the projected depth measurements in the region of interest; and generating a support structure plane definition based on the candidate subset of depth measurements.