The radiation fields of jet fires are highly anisotropic, exhibiting a significant ray effect, making their calculation potentially a computationally intensive process. Two quadrature strategies for evaluating the incident radiative flux distribution are presented and analysed, both strategies are shown to be highly efficient. As well as mitigating the ray effect by improvements in computational efficiency, false convergence is avoided as numerical error estimates and bounds are derived and demonstrated to be sharp. (C) 2000 BG Technology.