PATRIOT MISSILE DEFENSE: Software Problem Led to System Failure at Dhahran, SaudiArabia

摘要

On February 25, 1991, a Patriot missile defense system operating at Dhahran,Saudi Arabia, during Operation Desert Storm failed to track and intercept an incoming Scud. This Scud subsequently hit an Army barracks, killing 28 Americans. This report responds to Rep. Wolpe' request that the General Accounting Office(GAO) review the facts associated with this incident and determine if a computer software problem was involved. If so, the Reprentative asked GAO to provide information on what the specific software problem was, and what has been done to correct it. Appendix I details our objectives, scope, and methodology. The Patriot battery at Dhahran failed to track and intercept the Scud missile because of a software problem in the system's weapons control computer. This problem led to an inaccurate tracking calculation that became worse the longer the system operated. At the time of the incident, the battery had been operating continuously for over 100 hours. By then, the inaccuracy was serious enough to cause the system to look in the wrong place for the incoming Scud. The Patriot had never before been used to defend against Scud missiles nor was it expected to operate continuously for long periods of time. Two weeks before the incident, Army officials received Israeli data indicating some loss in accuracy after the system had been running for 8 consecutive hours. Consequently, Army officials modified the software to improve the system's accuracy. However, the modified software did not reach Dhahran until February 26,1991-the day after the Scud incident.