  The angle dependent thermal conductivity of the heavy-fermion superconductor
UPd$_2$Al$_3$ in the vortex state was recently measured by Watanabe et al. Here
we analyze this data from two perspectives: universal heat conduction and the
angle-dependence. We conclude that the superconducting gap function
$\Delta({\bf k})$ in UPd$_2$Al$_3$ has horizontal nodes and is given by
$\Delta({\bf k}) =\Delta\cos(2\chi)$, with $\chi = ck_{z}$.
