A
tactical air navigation system, commonly referred to by the
acronym TACAN, is a
navigation system used by military aircraft. It provides the user with bearing and distance (slant-range) to a ground or ship-borne station. It is a more accurate version of the
VOR/
DME system that provides
bearing and
range information for
civil aviation. The
DME portion of the TACAN system is available for civil use; at
VORTAC facilities where a VOR is
combined with a TACAN, civil aircraft can receive VOR/DME readings.Aircraft equipped with TACAN
avionics can use this system for enroute navigation as well as
non-precision approach to landing fields. The
space shuttle is one such vehicle that was designed to use TACAN navigation (although it has since been upgraded with
GPS as a replacement).
The typical TACAN onboard user panel has control switches for setting the channel (corresponding to the desired surface station's assigned frequency), the operation mode for either Transmit/Receive (T/R, to get both bearing and range) or Receive Only (REC, to get bearing but not range). Capability was later upgraded to include an Air-to-Air mode (A/A) where two airborne users can get relative slant-range information. Depending on the installation, Air-to-Air mode may provide range, closure (relative velocity of the other unit), and bearing, though an air-to-air bearing is noticeably less precise than a ground-to-air bearing.
History
The TACAN navigation system is an evolution of......
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