Geographical Range (Superseded)
Superseded by new definition from Guideline G1065
The maximum distance at which light from a light or other aid to navigation can reach an observer, as limited only by the curvature of the earth and refraction in the atmosphere and by the heights of the observer and of the light or aid.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM