"We lost everything. We lost all power to phone lines, computers, everything," said Allen Kenitzer, a regional spokesman for the FAA.
The outage could potentially affect air traffic nationwide, he said. Some planes were able to land because smaller facilities were helping to communicate with them, Kenitzer said.
"Safety is never compromised, but obviously it's caused an inconvenience," he said.
The outage at the Los Angeles Air Route Traffic Control Center was reported around 6 p.m., Kenitzer said, and the cause was not known.
The center is located in the high desert near Palmdale and handles high-altitude aircraft in Southern California and parts of Arizona, Nevada and Utah.