A wealth of knowledge resulted from the investigations into gross deviations from the great circle path (GCP) outlined below. The magnitude and variances of the deviations from the GCP have been quantified and the associated geophysical conditions and signal characteristics identified. Research is currently being undertaken aimed at incorporating the knowledge gained from the experiments into techniques that will be of direct operational application. The main activities in this area include the development of ionospheric models coupled with ray tracing studies (some preliminary results of which were presented here) both to confirm the cause of the large bearing deviations and to assess the impact of the presence of the high latitude ionospheric features causing the deviations on paths other than those subjected to experimental investigation.