The 2006 ultrasonic benchmark problem involves pulse-echo angle beam scanning of a notch located on an inclined planar back surface. The response from a side-drilled hole is to be used as a reference. The models are to simulate (a) the peak-to-peak B-scan P- and SV- responses of the slots normalized by the appropriate SDH response and (b) the maximum peak-to-peak corner response of the slots (either mode-converted or not). At CNDE, several simulation tools are being developed to assess/predict UT response for various geometries. The Finite-Difference-Time-Difference (FDTD) scheme is one such simulation tool that has been under development in 1D, 2D and 3D. The FDTD is an explicit time domain tool that can simulate pulse propagation characteristics in acoustic/elastic media. The computational domain is limited by implementing Perfectly Matched Layers (PMLs) at the domain boundaries. We present the results of calculations based on 2D FDTD to determine the response of rectangular shaped surface-breaking defects located on an inclined planar back surface. Comparisons will be made between predictions and measurements made available for the pulse-echo response. © 2007 American Institute of Physics.