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Coordinating Los Angeles air defenses in 1941

Coordinating Los Angeles air defenses in 1941

Dec. 23, 1941: Barely two weeks after the Japanese attack on Pearl Harbor, women volunteers plot the reported positions of aircraft in the skies over Southern California on a huge, kidney-shaped “filter” board.

The photo above by former staff photographer Al Humphreys accompanied a story in the Dec. 26, 1941, Los Angeles Times reporting:

At headquarters for the air raid warning system, women reported as usual for duty in keeping tab on every plane reported in the air over this area–whether it be friend or foe. As usual into Maj. J. E. Totten’s signal corps set-up cracked reports from hundreds of civilian aircraft spotters.

The information was transformed into an ever-changing scene on a huge kidney-shaped filter board–on which women volunteers manipulated chips representing the planes described to them through headphones.

Tied into the setup were connections into the Air Corps’ operations department–ready to send interceptor planes to the scene if an enemy or unidentified planes should be recorded…

The three photos below were published in the Dec. 28, 1941, Los Angeles Times Sunday Rotogravure section. The accompanying text reported:

In 1400 observation posts systematically located throughout California, thousands of observers, many women volunteers, today are maintaining a ceaseless vigil for enemy planes. If a raider is spotted the observer will flash the alarm to the nearest filter center (located in the Southland at Los Angeles, San Diego and Bakersfield.) When the report is verified Army flyers will leap to their planes and in a twinkling will be charging at the enemy, while co-ordinated searchlights and anti-aircraft guns to into action to support them in the sky battle.

The first photo below was taken at the same air raid warning center as the image above, but from the other side of the room. The other two below were taken at March Field near Riverside.

December 1941: On this master filter board, observers’ reports of aircraft are plotted. The information is transmitted to the Army by trained women volunteers who serve without pay. This board is the air-raid nerve center for Southern California. Credit: Los Angeles Times

December 1941: Telephone operators at March Field relay information from Southland plane observers to a master filter board where the planes’ positions are plotted and tracked. Credit: Los Angeles Times.

December 1941: Army Air Corps operatives check spotters’ reports on filter board at March Field before sending interceptor planes aloft. Credit: Los Angeles Times.

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