The AIS-SART is a self-contained radio device used to locate a survival craft or distressed vessel by sending updated position reports using a standard Automatic Identification System (AIS) class-A position report.
The position and time synchronization of the AIS-SART are derived from a built in GNSS receiver (e.g. GPS). Shipboard Global Maritime Distress Safety System (GMDSS) installations include one or more search and rescue locating devices. These devices may be either an AIS-SART (AIS Search and Rescue Transmitter) (from January 1, 2010), or a radar-SART (Search and Rescue Transponder).
The AIS-SART derives position and time synchronization from a built in GNSS receiver. Once per minute, the position is sent as a series of eight identical position report messages (four on 161.975 MHz and four on 162.025 MHz). This scheme creates a high probability that at least one of the messages is sent on the highest point of a wave.
AIS SARTs are typically cylindrical and brightly coloured.
Traditionally SARTs were based on RADAR technology. When the SART was activated it would wait until a RADAR signal from a passing vessel was received, then emit a series of RADAR pulses. The SART would appear as a series of RADAR returns on the ships RADAR display leading to the SARTs location.
An AIS SART does not use RADAR technology, instead it transmits AIS messages containing accurate GPS position information. These messages can be received by any vessel with AIS and can generate an alarm linked to the exact location of the SART. AIS and RADAR SARTs are considered equivalent by maritime authorities.