The “tri-axial velocity-sensor” has three axes that are nominally perpendicular, but may be nonperpendicular in practice, due to real-world imperfections in manufacturing, deployment, or maintenance.This paper comprehensively investigates how such non-perpendicularity would affect the tri-axial velocitysensor’s azimuth-elevation beam-pattern in terms of the beam’s pointing direction. It was shown that thenon-perpendicular axes do not affect the overall shape of the beampattern, but would introduce a pointingbias.