A radar transponder that responds to X-band radar pulses to indicate the position of a survival craft to SAR aircraft and vessels.
Quick facts
Regulation
SOLAS Chapter III
In practice
On watch, the officer of the watch must recognise the SART signature on radar and understand that it indicates a survivor in the water or in a survival craft. The display pattern shifts to twelve concentric circles as the searching vessel closes within about one nautical mile. The device operates for a minimum of ninety-six hours in standby mode and eight hours in active transmission.
Regulatory detail & full definition
A Search and Rescue Transponder is a portable radar-activated beacon carried under SOLAS Chapter III requirements in survival craft and survival equipment. When a vessel is in distress, the SART is activated and responds to 9 GHz (X-band) radar pulses from SAR aircraft or ships with a distinctive series of twelve blips on their radar display, arranged in a straight line extending away from the SART position.
On watch, the officer of the watch must recognise the SART signature on radar and understand that it indicates a survivor in the water or in a survival craft. The display pattern shifts to twelve concentric circles as the searching vessel closes within about one nautical mile. The device operates for a minimum of ninety-six hours in standby mode and eight hours in active transmission.
SARTs are tested monthly using a dedicated test mode that verifies the alarm light and transmission without broadcasting a false distress. SOLAS Regulation III/6 covers carriage requirements, and annual servicing must be recorded. AIS-SARTs are increasingly common and transmit a digital AIS distress message in addition to the radar response, offering greater compatibility with modern bridge systems.