World War II searchlights were part of an aircraft detection system linking a locator device, searchlights, and antiaircraft guns. The locators sent electronic information to the lights and guns, which then tracked the target in synch with each other. Once a locator had locked on to an aerial target, both lights and guns were to be trained on it using height and distance data from the locator so the target could be nearly simultaneously illuminated and then destroyed. Locators were first based on sound and heat detections, and radar ultimately became the preferred method of target acquisition. Although the units were generally separate, advances in radar technology late in the war led to the integration of radar into both searchlight and antiaircraft gun designs.