not ruling out the possibility of
sabotage by computer hackers, but most seemed to think the problems
stemmed from some unknown defect in the software running the networks."
And sure enough, within the week, a red-faced software company, DSC
Communications Corporation of Plano, Texas, owned up to "glitches" in
the "signal transfer point" software that DSC had designed for Bell
Atlantic and Pacific Bell. The immediate cause of the July 1 Crash was
a single mistyped character: one tiny typographical flaw in one single
line of the software. One mistyped letter, in one single line, had
deprived the nation's capital of phone service. It was not
particularly surprising that this tiny flaw had escaped attention: a
typical System 7 station requires TEN MILLION lines of code.
On Tuesday, September 17, 1991, came the most spectacular outage yet.
This case had nothing to do with software failures--at least, not
directly. Instead, a group of AT&T's switching stations in New York
City had simply run out of electrical power and shut down cold. Their
back-up batteries had failed. Automatic warning systems were supposed
to warn of the loss of battery power, but those automatic systems had
failed as well.
This time, Kennedy, La Guardia, and Newark airports all had their voice
and data communications cut. This horrifying event was particularly
ironic, as attacks on airport computers by hackers had long been a
standard nightmare scenario, much trumpeted by computer-security
experts who feared the computer underground. There had even been a
Hollywood thriller about sinister hackers ruining airport
computers--DIE HARD II.
Now AT&T itself had crippled airports with computer malfunctions--not
just one airport, but three at once, some of the busiest in the world.
Air traffic came to a standstill throughout the Greater New York area,
causing more than 500 flights to be cancelled, in a spreading wave all
over America and even into Europe. Another 500 or so flights were
delayed, affecting, all in all, about 85,000 passengers. (One of these
passengers was the chairman of the Federal Communications Commission.)
Stranded passengers in New York and New Jersey were further infuriated
to discover that they could not even manage to make a long distance
phone call, to explain their delay to loved ones or business
associates. Thanks to the crash, about four and a half million
domestic calls, and half a million international calls,
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