At what point does a SART begin transmitting?

A Search and Rescue Transponder (SART) operates by receiving a specific radar signal, which typically operates on the 9 GHz frequency. When it is placed in the "on" position, it does not immediately begin transmitting independently. Instead, its primary function is to respond to an external interrogation signal. The SART requires a radar signal to trigger its activation, ensuring that it only transmits when needed—specifically, when a vessel's radar queries it.

This feature is crucial for avoiding unnecessary signals that could overwhelm search and rescue operations. The SART is designed to assist in locating distressed vessels or persons by providing a clearer, stronger response to radar sweeps, thus enhancing the chances of successful recovery. The response to a specific radar interrogation helps ensure that the SART's signal is both purposeful and effective in search operations.