  In our previous papers [arXiv:2106.03150, arXiv:2110.10917,
arXiv:2208.00822], we analyzed the asymptotic behavior of future directed null
geodesics near future null infinity and then we showed a proposition on the
accessibility of the null geodesics to future null infinity in a specific class
of asymptotically flat spacetimes. In this paper, we adopt the retarded time of
the Bondi coordinate as the parameter for the null geodesics and then see that
one can relax the assumptions imposed in our previous studies. As a
consequence, we obtain a new null-access theorem for generic asymptotically
flat spacetimes.
