The relation between surface “Fermi-arcs” and bulk Weyl cones in a Weyl semimetal, uniquely allows to study the notion of bulk to surface correspondence. We visualize these topological Fermi arc states on the surface of the Weyl semi-metal tantalum arsenide using scanning tunneling spectroscopy. Its surface hosts 12 Fermi arcs amongst several other surface bands of non-topological origin. We detect the possible scattering processes of surface bands in which Fermi arcs are involved including intra- and inter arc scatterings and arc-trivial scatterings. Each of the measured scattering processes entails additional information on the unique nature of Fermi arcs in tantalum arsenide: their contour, their energy-momentum dispersion and its relation with the bulk Weyl nodes. We further use the spatial structure of the surface states’ wave function to distinguish and characterize the surface Fermi arc bands. The trivial states have a complex structure within the unit cell, whereas the Fermi arc wave function is essentially plane-wave like. It is weakly affected by the surface potential and thus spreads rather uniformly within the unit cell. We obtain these results using an analysis technique, based on the role of the Bloch wave function in shaping quantum electronic interference patterns. It thus carries broader applicability to the study of other electronic systems and other physical processes.