The Amateur Radio Emergency Service® (ARES®) is a volunteer organization of trained amateur radio ("ham" radio) operators established to assist in public service and emergency communications. It is organized by the American Radio Relay League in the U.S., and by the Radio Amateurs of Canada. Amateur radio communications, throughout the history of radio, has been a dependable, and often the only method of communication available during natural and man-made disasters.
It's not uncommon for communications systems to breakdown or become overloaded during a disaster. Radio amateurs have routinely stepped up to fill in the gap when other forms of communications have either failed, or become congested. This has been the case time and time again, including the disasters of the attacks on September 11, 2001, Hurricane Katrina, and most recently the deadly tornadoes in Alabama and Missouri, where ARES® teams were vital to the early response and relief efforts of those events. During Katrina, over a thousand ARES® volunteers provided communications for the American Red Cross, The Salvation Army, and other organizations. In fact, in the aftermath of the hurricane, Hancock County, Mississippi was left completely without communications... except for ARES® operators who stepped up and served as 911 dispatchers. As a result of these efforts, the Department of Homeland Security 2007 Appropriations Act HR-5441, officially includes Amateur Radio Operators as a part of the emergency communications community.
In a more local example, it was the amateur radio operators of the Clarksville Amateur Transmitting Society that saved the day during and after the 1999 tornado devastated the city of Clarksville, TN. "Amateur radio was the only reliable means of communications for the first 12 hours after the tornado struck," said John White, director of the Tennessee Emergency Management Agency (TEMA). They made it possible for first responders, organizations like the Red Cross, and victims to communicate with each other.
However, amateur radio is not just a replacement communications method when other systems aren't functioning. ARES teams are often utilized to supplement as auxiliary communications. Many times the amateur operators are asked to provide important support radio traffic in order to keep emergency frequencies less congested.
Radio amateurs have been responding to serve the public since the 1930's. It's in this tradition that ARES® groups across the country continue to train and prepare to be there.