  The vanishing of the cross section for particular points in phase space -
radiation zeros - is examined for the process $ q \bar q \to W^+W^- \gamma$ at
high energy. For photon energies that are not too large, the cross section does
exhibit deep dips in regions of phase space corresponding to the position of
the actual zeros. We show that in these regions the sensitivity to possible
anomalous quartic couplings is very large.
