Vordac for precise navigation over very-high-density air-traffic routes

After discussing the bearing and range accuracies achievable with VOR-DME, the authors describe a method of obtaining a 6:1 reduction in errors by Introducing a 5th harmonic signal. Aircraft equipped with VOR-DME could obtain the improvement by the addition of a simple computer unit. Operation of the unit on radial and non-radial courses is described. In view of the need to integrate the navigational system into an overall system of ATC, the principles of operation and the possibilities of secondary radar and datarama type systems of transmitting flight information are outlined. Proposals for establishing the necessary Vordac equipment in Europe, In conjunction with Tacan, are also given.