Navigation errors using omega at ranges close to a transmitter

Experimental measurements of the propagation characteristics of the basic OMEGA frequencies 10.2 and 13.6kHz, made in August 1966, taken over air routes within 2000km of the OMEGA Trinidad transmitter, are used to estimate errors in navigation due to the presence of more than one waveguide-propagation mode close to a transmitter. During the day, the maximum likely error due to propagation effects using the frequencies 10.2 and 13.6kHz are of the order of ±3km at 300¿400km from a transmitter. For night conditions, errors that are multiples of a lane width (15km for 10.2kHz and 11km for 13.6kHz) will be experienced.