TACAN (Tactical Air Navigation)
TACAN (Tactical Air Navigation) is a military UHF radio navigation system that provides bearing and distance (slant range) to a TACAN station. In joint-use installations (VORTAC), civilian aircraft use the DME component; military aircraft use both bearing and distance.
TACAN vs. VOR-DME
VOR provides bearing on VHF; TACAN provides bearing on UHF. Both provide DME distance. When a TACAN is co-located with a VOR as a VORTAC, civilian aircraft receive VOR bearing on their VOR receiver and TACAN-derived distance on their DME. The two systems use the same DME interrogator/transponder technology.