Tactical air navigation system
A tactical air navigation system, commonly referred to by the acronym TACAN, is a navigation system initially designed for naval aircraft to acquire moving landing platforms (i.e., ships) and later expanded for use by other military aircraft. It provides the user with bearing and distance (slant-range or hypotenuse) to a ground or ship-borne station. It is, from an end-user perspective, a more accurate version of the VOR/DME system that provides bearing and range information for civil aviation. Aircraft equipped with TACAN avionics can use this system for enroute navigation as well as non-precision approaches to landing fields.
The distance-measuring portion of TACAN is fully interoperable with civilian DME while the bearing-measurement is not interoperable with VOR. VORTAC facilities combine a VOR with a TACAN so that civilian aircraft can use it as VOR/DME while military aircraft can use it as TACAN. TACAN-only equipped aircraft cannot receive bearing information from a VOR-only station.