The implementation of plane wave incidence using the total-field/scattered-field (TFSF) formulation for a three-dimensional finite volumes-based, extended-stencil finite-difference time-domain (FV24) algorithm is presented. This achievement required designing an auxiliary one-dimensional grid with the characteristics of (i) co-located electric field components uniformly spaced from co-located magnetic field components, (ii) grid spacing that dynamically changes with desired angles of propagation to eliminate the need for field interpolations when mapping the plane wave to the main grid, (iii) update equations that precisely match the numerical dispersion characteristics of the main FV24 algorithm, and (iv) auxiliary to main grid field mapping that encompasses six parallel surfaces along the TFSF boundary to satisfy the extended cell nature of the main FV24 algorithm. The resulting non-physical field leakage into the scattered-field region is observed to be independent of angle of incidence and has a −300 dB noise floor. This technique extends the high-order FV24 capabilities to include accurate and efficient simulations of electrically large scatterers using relatively low grid densities, bringing this capability to today's desk-side workstations.