On August 14, 2003, a race-condition bug in General Electric Energy’s Unix-based XA/21 energy-management system stalled FirstEnergy’s control-room alarm system for more than an hour. Operators lost both audio and visual warnings while transmission lines in the Cleveland–Akron area overheated and sagged into trees. The outage began after high demand, an Eastlake generating-unit shutdown, and several transmission failures; operators were unaware of the deteriorating grid and did not redistribute load or shed power in time.
The U.S.-Canada Power System Outage Task Force’s April 2004 final report found that the failed alarm system, inaccurate or unavailable grid models, inadequate tree trimming, offline voltage-support equipment, and communication failures combined into a cascading collapse. More than 508 generating units at 265 power plants shut down, cutting power to an estimated 55 million people in eight U.S. states and much of Ontario. On November 19, 2003, U.S. Energy Secretary Spencer Abraham said the federal government would not punish FirstEnergy because U.S. law then lacked enforceable electricity-reliability standards. The blackout prompted major reliability investments and strengthened scrutiny of North American grid operations.