A fiber optic optical time domain reflectometer-based (OTDR) sensing system is described for detecting the extent and/or location of damage incurred by a composite material following an impact event. Two multi-mode fibers are embedded within a graphite composite to form a 'checkerboard' fiber mesh with 0.5 inch spacing. The measurement system consists of a PC- based virtual instrument, a high resolution optical time domain reflectometer, and two fiber optic sensors. Using the OTDR and processing algorithms, the location of impact can be determined within the composite panel by scanning the length of each fiber from both ends. The OTDR scanning process yields four reference points which can be used to determine the location of the impact referenced to a coordinate axes designated within the composite panel.