A federal report blames the September 2011 blackout of 2.7 million customers in Southern California, Arizona and Baja California on "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."

The 153-page report came out issued Wednesday after a nearly eight-month inquiry by staff of the Federal Energy Regulatory Commission and North American Electric Reliability Corp.

It recommends that transmission operators and balancing authorities improve how they plan for operations to account for the status of facilities outside their individual systems, the effect of external operations on their own systems and how operation of transmission facilities under 100 kV can affect the reliability of the bulk-power system.

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