Auxiliary Communications Service

We are trained volunteers who use amateur radio for disaster communication.

About us

We are trained professionals who provide communications support to the agencies of the City and County of San Francisco. We focus on emergency support for major events or incidents. Our goal is to support the gathering and distribution of information necessary to respond to and recover from a disaster. Our standard method of communication is amateur radio (ham radio). We also use many other means of communication, including telephone, fax, email, text messaging, social media and public service radio.

Most ACS volunteers are licensed Amateur Radio operators. Individuals with other technical and communications skills are also welcome to apply. We provide training in basic emergency communications, as well as in-depth training and exercises. Our personnel become familiar with the many City agencies we serve.

The San Francisco Department of Emergency Managment organized the ACS following the 1989 Loma Prieta earthquake. ACS supports the communications needs of the City and County of San Francisco during emergencies and special events.

ACS resources

The Auxiliary Communications Service resources page contains forms, scripts and manuals that can be downloaded.

ACS radio nets

A "net" (short for "network") is a time when radio operators call in on a single frequency to check in and/or to share information.

Participating in a formal radio net and being a good Net Control Operator are important skills. The best time to learn is before a disaster happens. ACS conducts local radio nets each week to give radio operators living or working in San Francisco the opportunity to learn and practice these needed skills in a low-stress environment. ACS nets are meant to simulate the transfer of emergency messages. Within a "directed net" please remember your ABC's: Accuracy, Brevity, and Clarity.

The ACS weekly net
The ACS Net begins at 1930 hours (7:30 pm) local time each Thursday evening, on the WA6GG repeater at 442.050 MHz, positive offset, tone 127.3 Hz. The purpose of this net is to practice Net Control skills, practice checking in with deployment status in a formal net, and to share information regarding upcoming ACS events. All licensed amateur radio operators are welcome to check in. On the second Thursday of each month, a simplex version of the net is conducted on the output frequency of the WA6GG repeater, 442.050 MHz, no offset, tone 127.3 Hz.

The Travel Net
The ACS Travel Net begins at 1815 hours (6:15 pm) local time immediately before each ACS General Meeting (generally the third Tuesday of each month), on the WA6GG repeater at 442.050 MHz, positive offset, tone 127.3 Hz. The purpose of this net is to practice Net Control skills in a 1-on-1 supervised environment and to practice checking in with in-process deployment status in a formal net. All licensed amateur radio operators are welcome to check in.

Scripts for ACS nets
The ACS Resources page contains scripts that are used in the various nets.

Many thanks to the Northern California Amateur Radio Group for providing the WA6GG repeater for ACS nets and activities.

The Siren Net
Please visit the Outdoor Public Warning System webpage for information about the Siren Net which has been temporarily suspended.

Related Links

Sign up to receive emergency alerts. Text your zipcode to 888777 or visit to sign up.

Be prepared! Make a personal and family disaster plan today.

California OES ACS
California Emergency Management Agency - Auxiliary Communications Service

San Francisco Neighborhood Emergency Response Team

Amateur Radio Relay League

Radio Amateur Civil Emergency Service

Last updated November 30, 2022