- 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:
- Relieve radio congestion on the primary channel/talkgroup by moving heavy and/or event-specific radio traffic to the secondary Tac/TAC channel/talkgroup,
- Improve clarity and safety for event-specific communications by providing a (possibly encrypted) dedicated or temporarily assigned channel/talkgroup free from unrelated radio traffic.
- 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:
- 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.
- Used for chat between aircraft while operating on another frequency
- Used for operations when not being controlled by another facility.