U.S.

Flaws cited in huge 2011 blackout in Southwest U.S.

May 1, 2012 / 2:26 PM EDT / AP

(AP> SAN DIEGO — Federal energy regulators on Tuesday blamed inadequate planning and lack of grid coordination for a blackout last year that affected millions of people in Southern California, Arizona and Mexico's Baja California.

San Diego pizza restaurants serves up dinner in the dark — Workers serve pizza to customers outside Filippi's Pizza after a massive blackout hit Southern California, Sept. 8, 2011, in San Diego, California. Sandy Huffaker/Getty Images

The staff of the Federal Energy Regulatory Commission and North American Electric Reliability Corp. said in a statement that the Sept. 8 outage "stemmed from operating in an unsecured state due to inadequate planning and a lack of observability and awareness of system operating conditions on the day of the event."

Details were being released in a teleconference from Washington, D.C.

"This report highlights the growing need for more coordination of grid operations in the West," FERC Chairman Jon Wellinghoff said in a statement.

Gerry Cauley, president and CEO of NERC, said the outage underscores the complexity and interdependence of the North American electric system and the importance of information sharing and system studies.

Utility officials previously said an employee's work on a transmission line at an Arizona substation was the first action in the chain of events, but it should not have triggered such a massive blackout because the system is built to quickly compensate for such glitches.