What was the equipment used to detect Japanese planes on December 7, 1941?

The SCR-270 B-Radar played a crucial role on December 7, 1941, as it was one of the first operational military radars used by the United States. This radar system was designed to detect aircraft and provide early warning, which was especially important during the surprise attack on Pearl Harbor. The SCR-270 was capable of identifying incoming hostile aircraft, allowing for timely alerts to ground and air defense forces.

Its significance during the attack lies in the fact that although it was operational, the radar's potential was not fully utilized, leading to missed opportunities for an early defense response. The SCR-270's ability to detect the Japanese planes thus positions it as the correct choice in this context, highlighting its historical importance in military radar technology and its role during a pivotal moment in World War II.