Primary Alert System

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File:PACCS Primary Alert System.JPG

The Primary Alerting System (PAS), was a network of land-line connections used by the Strategic Air Command (SAC) for command and control of its nuclear forces. PAS provided immediate and simultaneous voice communications to all (SAC) unit command posts and missile launch control facilities.{{Cite web |date=2025-01-24 |title=How to make sure you're getting evacuation alerts during a fire |url=https://www.cbs8.com/article/news/local/how-do-i-get-alerted-for-evacuations-in-san-diego/509-097f0919-17e2-4b70-a075-050d8b50e5d9 |access-date=2025-02-06 |website=cbs8.com |language=en-US}}

File:SAC Museum Red Phone 2020.jpg underground command post in June 1959. Now on display at the SAC museum.]]

PAS reached each Command Post by two geographically diversified circuits; one circuit, commonly called the "front-door" circuit tied the unit directly to Headquarters (SAC); the other, or "back-door" circuit provided a link to the parent Numbered Air Force.