The degree of conformance between the estimated or measured parameter of a craft at a given time and its true parameter at that time. (Parameters in this context may be position co-ordinates, velocity, time, angle, etc.)
– Absolute accuracy (Geodetic or Geographic accuracy). The accuracy of a position estimate with respect to the geographic or geodetic co-ordinates of the Earth.
– Geodetic or Geographic accuracy. See absolute accuracy.
– Predictable accuracy. The accuracy of the estimated position solution with respect to the charted solution.
– Relative accuracy. The accuracy with which a user can determine position relative to that of another user of the same navigation system at the same time.
– Repeatable accuracy. The accuracy with which a user can return to a position whose co-ordinates have been measured at a previous time using uncorrelated measurements from the same navigation system.
Source: Nick Ward, Vicechair, IALA e-Nav Committee, March 2009
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM