We investigate the stability of a trailing vortex using mean flow profiles given by an approximate solution of the Navier-Stokes equations. The axial and tangential velocity profiles obtained from this solution, deduced by Moore & Saffman (1973), agree well with experiments involving wings at slight angles of attack. In particular, jet-like and wake-like flows near the center of the vortex provide a better description of the axial flow than the much-studied Batchelor vortex. We find that they accurately describe the flow at short and intermediate distances behind the wingtip. Growth rates for unstable perturbations will be presented and shown to be considerably larger than those for the Batchelor vortex.