At what point does a SART begin transmitting?

A Search and Rescue Transponder (SART) is a device used primarily in maritime situations to help search and rescue teams locate ships in distress. The correct choice states that if the SART has been placed in the "on" position, it will respond when it has been interrogated by a 9-GHz RADAR signal. This highlights the way SART devices are designed to operate: they do not continuously transmit a signal but instead wait to be activated by an external RADAR signal.

Once the SART detects this specific RADAR signal, it responds by transmitting a series of distinctive pulsing signals that are easily identifiable on RADAR displays. This response mechanism allows SARTs to conserve power and ensures that they only transmit when needed to alert potential rescuers of a vessel in distress, enhancing their effectiveness in search and rescue operations.

Options that involve immediate transmission when turned on or requiring manual activation do not accurately represent the operational design of a SART, as its primary function is to react to specific RADAR inquiries rather than emitting a continuous signal or needing manual intervention to activate its transmitting capabilities.