The results of a program are reported whose objective has been to establish the reliability and accuracy of tissue kerma estimates near the ground, out to deep penetration ranges, from a point neutron source in an air-over-ground geometry. The results take the form of expected error in calculated neutron and secondary gamma-ray kerma out to 2-km range for any neutron source height and energy spectrum. In the first of two approaches, experimental data permitting absolute evaluation in one dimension is used in conjunction with an evaluated calculational procedure for two dimensions to obtain overall error estimates. In the second approach, errors obtained from comparisons of measurement and calculation in air-over-ground geometry are evaluated to obtain overall error estimates. When the results of these two approaches are averaged, it can be concluded with confidence that kerma to 2 km will probably be calculated to be 10 to 15% lower than measured values for neutrons and 20 to 25% lower for gamma rays when this cross-section set and recommended calculational procedure or equivalents are used.