Unlike commercial systems, Amateur radio is usually independent of terrestrial facilities that can fail. It is dispersed throughout a community without “choke points” such as cellular telephone sites that can be overloaded.
Amateur radio operators are experienced in improvising antennas and power sources and most equipment today can be powered by an automobile battery. Annual “Field Days” are held in many countries to practice these emergency improvisational skills. Amateur radio operators can use hundreds of frequencies and can quickly establish networks tying disparate agencies together to enhance interoperability.
Recent examples include the September 11 attacks on the World Trade Center in Manhattan in 2001, the 2003 North America blackout and Hurricane Katrina in September 2005, where amateur radio was used to coordinate disaster relief activities when other systems failed.