Definition
A military air navigation system that provides a pilot with both bearing and distance information to a selected ground station, transmitting in the ultra-high frequency (UHF) band. Civilian aircraft equipped with DME (distance measuring equipment) can use the distance portion of a TACAN station, and TACAN stations are often co-located with civilian VOR stations to form a combined facility known as a VORTAC.
Plain English
A military ground station that tells a pilot two things at once: which direction the station is, and how far away it is. Civilian aircraft can usually pick up the distance part of the signal even though they can't use the direction part.
Context Anchor
Seen in military navigation, shipboard operations, and on charts where military navigation stations or combined civil-military navigation facilities are listed.
Derivation
From 'tactical' (relating to military operations) and 'air navigation' (finding your way through the air). The name reflects its origin as a military system designed for the operational needs of fast-moving tactical aircraft.
Why Pilots Care
It gives military pilots reliable distance and direction data independent of civilian navigation networks, which is essential in tactical or combat environments.
Intuition Check
Tactical does not mean a special flying maneuver here. It means the navigation system was designed for military operational use.
Example Sentence 1
The chart showed a VORTAC, which combines a civilian VOR with a military Tactical Air Navigation station at the same site.
Example Sentence 2
During the low-level route, the crew relied on Tactical Air Navigation for accurate positioning over unfamiliar terrain.