It is pointed out that the demand by navigators for more information in a given time or for the same information in a shorter time can only be met at the price of increased complexity (and, therefore, cost) and unreliability. To provide examples supporting this statement, a number of well-known systems are described briefly; for example, in the family of hyperbolic systems there is a clear indication that those providing immediate access to an unambiguous fix are more complex, in the wide sense, than those achieving similar accuracy but at the expense of ambiguities. This is even more true when various degrees of automatic operation and display are considered, and the paper includes a description of some of the techniques involved in the provision of these facilities. Finally, brief reference is made to the suitability for automatic computing of the geometry of the various systems and it is pointed out that those working in polar coordinates or Earth axes (such as VOR/DME and doppler/compass respectively) have advantages over the hyperbolic systems.