From The RadioReference Wiki

  • Tac or TAC is an abbreviation for "Tactical".
  • TAC is also an abbreviation for "Talk-Around Channel".

  • As defined above, Tac and TAC broadly describe a dedicated or temporarily assigned, non-primary radio channel (repeated or simplex) or TRS-Talkgroup, used for at least one of the following general purposes:
    1. Relieve radio congestion on the primary channel/talkgroup by moving heavy and/or event-specific radio traffic to the secondary Tac/TAC channel/talkgroup,
    2. Improve clarity and safety for event-specific communications by providing a (possibly encrypted) dedicated or temporarily assigned channel/talkgroup free from unrelated radio traffic.
    3. Improve direct unit-to-unit simplex communication when the repeater-site is out of range.

  • Specific purposes for Tac channels/talkgroups can vary greatly. Examples:
    • SWAT units use an encrypted Tac channel for secure communications.
    • Fireground Operations use one Tac channel/TG, while Water Supply Operations uses another.
    • Interior units use the Talk-Around Channel to talk to each other and exterior units.
    • Buses at a sports event use a Tac channel for the duration of the event.
    • For Aviation and Military users, Tac describes frequencies that are one of the following:
      1. Assigned to a particular squadron.
        • For instance, the DC-ANG at Andrews AFB has its own list of squadron tac freqs it uses on a regular basis and are preset in their VHF radios.
      2. Used for chat between aircraft while operating on another frequency
      3. Used for operations when not being controlled by another facility.