You can read a more complete account of the accidents and the investigation in an
eWEEK article from March 2004 at http://www.findarticles.com/p/articles/mi_zdewk/is_200403/ai_ziff121063.
In 1991 during the first Gulf War, a software anomaly caused a Patriot missile battery protecting a barracks
of the US Army in Dhahran, Saudi Arabia to fail to fire at an incoming Iraqi Scud missile, even though the
system detected the missile en route. Twenty-eight soldiers died. The cause of the Patriot missile??™s battery
failure turned out to be an obscure software bug related to truncation of a variable used to keep time.
The Information Management and Technology Division of the US General Accounting Office provided
a complete report (http://www.fas.org/spp/starwars/gao/im92026.htm).
Originally the Patriot missile was designed to operate against aircraft and cruise missiles. It is a mobile
system designed to be set up in a location and operated for a few hours at a time before moving again. The
system was adapted to attack faster short-range ballistic missiles. To avoid firing the Patriot battery at false
alarms, the software controlling the battery would confirm the presence of an incoming missile by predicting
the incoming missile??™s future position based on the battery??™s early detection of the missile target.
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