  Neutron stars inspiralling into a stellar envelope can accrete at rates
vastly exceeding the Eddington limit if the flow develops pressures high enough
to allow neutrinos to radiate the released gravitational energy. It has been
suggested that this hypercritical mode of accretion leads inevitably to the
formation of stellar mass black holes during common envelope evolution. We
study the hydrodynamics of this flow at large radii (R >> R_ns), and show that
for low Mach number flows, in two dimensions, modest density gradients in the
stellar envelope suffice to produce a hot, advection dominated accretion disk
around the accreting object. The formation of outflows from such a disk is
highly probable, and we discuss the impact of the resultant mass loss and
feedback of energy into the envelope for the survival of the neutron star.
Unless outflows are weaker than those inferred for well observed accreting
systems, we argue that in most cases insufficient accretion occurs to force
collapse to a black hole before the envelope has been ejected. This conclusions
is of interest for black hole formation in general, for some models of gamma
ray bursts, and for predictions of the event rate in future LIGO observations.
