The report is devoted to the analysis of lightning electromagnetic pulse (LEMP) transformation in a process of its propagation in the Earth-ionosphere waveguide at distances up to ten thousands kilometers and its possible influence on the accuracy of lightning multi-station DTOA systems. We will consider the main features of this transformation in relation to such important parameters of DTOA location systems as detection efficiency and location accuracy focusing more attention to their far-zone (trans-continental) versions.