A software update on Monday night left Louisville residents unable to call 911 for help. For 2 hours the 32 phone lines were jammed, with dispatchers unable to disconnect the calls they had taken previously.

The error was related to the enhanced 911 system, designed to show dispatchers the addresses and telephone numbers of callers. The software upgrade was considered routine, although the results it produced by 9pm were anything but. By 11pm the telephone company had rerouted the lines to restore service and workers scrambled to call back anyone who had called during the outage, using the telephone records as reference.

Software glitches such as this are at the extreme end of things, but even more routine errors can cost lives - database errors listing the wrong address are common, and cause emergency personnel to be misdirected, preventing them from getting to where they are really needed.

With billions of dollars being poured into securing critical infrastructure from terrorism, software bugs are often overlooked - yet they can create the same devastating results as systems become increasingly complex.

Copyright © 2005, SecurityFocus

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