AIS SART

What sets AIS-SART apart

Where a conventional radar SART works passively, only responding when interrogated by a 9 GHz radar, an AIS Search and Rescue Transmitter actively broadcasts its own position, using an internal or built-in GPS fix, over AIS Class A message formats on the standard AIS VHF channels. Any vessel or aircraft with an AIS receiver within VHF range sees a distinctive AIS-SART icon and identity on its ECDIS or dedicated AIS display, together with the survival craft's position and course, without needing to be actively sweeping a radar at the time. The two devices solve the same problem with different physics and are frequently carried alongside each other rather than as substitutes.

Main components

GPS receiver

An internal satellite positioning receiver that fixes the unit's own position for inclusion in each transmitted message.

VHF transmitter

Transmits on the AIS channels in a distinctive repeating pattern recognised by receiving AIS equipment as a distress transmission rather than a normal vessel target.

Battery

A sealed primary battery sized for a standby period followed by a minimum active transmission duration, commonly rated for around 96 hours of operation once activated.

Float-free or manual housing

Some units are integrated with float-free arrangements similar to an EPIRB bracket; most survival-craft units remain manually deployed, carried into the raft or boat by crew.

Where it fits alongside other locating devices

An AIS-SART complements rather than replaces the EPIRB and radar SART already required aboard. The EPIRB alerts the shore-based search and rescue system via satellite; the radar SART and AIS-SART both help a searching unit that is already in the area pinpoint the exact position of survivors. AIS-SART has the advantage of working with any modern AIS-equipped ship, which now covers the large majority of the world merchant fleet, and of giving a clear position readout rather than requiring the searching officer to interpret a line of radar dots.

Regulations and class

IMO has accepted AIS-SART as an alternative to a radar SART under the GMDSS carriage requirements of SOLAS III, meaning a ship may satisfy part of its SART carriage requirement with an AIS-SART instead of, or alongside, a radar SART, subject to flag state acceptance. Equipment must carry appropriate type approval confirming compliance with the relevant IEC standard for AIS-SART performance.

Typical faults

• Expired battery — as with the radar SART, the most common failure found at survey is a battery past its marked expiry date.
• GPS fix delay in poor sky view — a unit activated inside a covered life raft can take longer to acquire a position fix, delaying the first accurate position report.
• Confusion with radar SART carriage credit — crews sometimes assume an AIS-SART satisfies the full SART carriage requirement when flag state rules only allow it as a partial substitute; this is a paperwork and compliance fault rather than a technical one.
• Weak signal from low antenna height — VHF range from a survival craft at sea level is limited, so detection range depends heavily on the searching vessel's own antenna height.

What to look for in a supplier

• Type approval confirming compliance with the applicable AIS-SART performance standard and flag state acceptance for carriage credit.
• Clearly marked battery expiry date and GPS fix time specification.
• Housing suited to the specific survival craft bracket already fitted.
• Confirmation of which portion of the SOLAS III SART requirement the unit is accepted to satisfy under the relevant flag administration.

Check with the flag administration before assuming an AIS-SART alone satisfies the full SART carriage requirement — some administrations still require at least one radar SART aboard regardless of AIS-SART fit.