Complex sentence: Amateur radio provides a means of communication when all others fail; for example, after Katrina Hancock County, Mississippi had lost all contact with the outside world, except through ARES operators who served as 911 dispatchers and message relayers.
Split into simpler sentences: Amateur radio provides a means of communication when all others fail. After Katrina Hancock County, Mississippi had lost all contact with the outside world, except through ARES operators who served as 911 dispatchers and message relayers.