Module 9 — SART, AIS-SART and survival VHF

Once the crew abandons ship, these devices allow them to be located and to communicate with the SAR units.

Radar SART (9 GHz)

When illuminated by an X-band radar, it replies with a line of 12 dots pointing towards the SART position; they turn into arcs and concentric circles as the SAR vessel closes in.

AIS-SART

Transmits GPS position via AIS every minute. More accurate and compatible with any AIS receiver, not only radar.

GMDSS portable VHF

Waterproof handheld with a sealed primary battery (emergency use only) and, on some sets, a rechargeable secondary battery for routine operation. Programmed on channels 6, 8, 16 and operational channels.

Combined use

In the life-raft: keep the SART / AIS-SART as high as possible; use the portable VHF for on-scene communication with ships and SAR helicopters; keep messages short and in maritime English.

Radar SART on 9 GHz (2.5.2.10)

The radar SART operates in the 9 GHz band and responds to an X-band radar interrogation from a nearby aircraft or ship with a series of 12 blips on the searcher's screen converging on the SART's position. Useful range is about 5 NM from a ship and 30–40 NM from an aircraft at 3000 ft. Standby autonomy is 96 hours; active operation 8 hours.

AIS-SART as alternative or complement

The AIS-SART transmits AIS messages with identity 970xxxxxx and position every minute for 96 hours. It appears on any AIS receiver within VHF range (typically 5 NM from a vessel, more from aircraft). The manual recognizes it as equivalent to the radar SART for the locating function (SOLAS IV/7.1.3).

Survival craft portable VHF (resolution MSC.149(77))

The survival-craft two-way portable VHF operates on maritime VHF channels (at least 16 and one other simplex channel). It is buoyant, watertight to 1 m for 1 hour, with a primary non-rechargeable battery for emergency use giving 8 hours of usable autonomy at full power, and a rechargeable battery for drills. The resolution requires at least three units on passenger ships and on cargo ships ≥ 500 GT.

On-scene aeronautical portable VHF

The carriage table in Part 6 also provides for aeronautical portable VHF on 121.5 / 123.1 MHz (AM) for liaison with SAR helicopters once the bridge is no longer practicable. This is typically required on passenger ships and in certain operations.

On-scene communications as a GMDSS function

Paragraph 2.5.2.8 confirms that on-scene communications are a distinct GMDSS function. That makes the SART and portable VHF links in the rescue chain, not liferaft accessories.

Test cadence and AIS-SART vs radar-SART choice

Both radar SART and AIS-SART have a monthly self-test run from the unit (without triggering a live alert) and an annual inspection covering battery and expiry. The radar SART shows on any 3 cm X-band radar within range; the AIS-SART additionally shows as a target with MMSI 970xxxxxx directly on the ARPA/ECDIS of any ship with an AIS receiver. The choice is rarely 'one or the other': in practice many survival-craft outfits carry both, because radars and AIS are not always simultaneously active on the ship that first picks up the signal.

Portable VHF: pre-drill check and battery

Before every drill or deployment the survival-craft VHF is tested with the rechargeable training battery, and it is verified that the primary emergency battery (non-rechargeable, sealed) is fitted in the stowed unit. Some units live on a float-free bracket on the survival craft; others are stowed with the lifejackets and carried by hand. The manual's carriage table expects strict watch over battery state: primary batteries out of date are an operational failure that should be caught at the annual inspection, not at the moment of abandoning ship.

Radar SART: pattern and ranges

When interrogated by an X-band radar (9.2-9.5 GHz) the SART replies with a train of 12 evenly spaced pulses that the searching radar paints as 12 aligned blips centred on own position and extending outward with ~0.6 NM spacing. When the searcher closes inside ~1 NM the 12 blips widen and merge into concentric arcs — an unmistakable 'close in' indicator. Detection range: from a ship with a radar antenna at 15 m, about 5 NM; from a SAR aircraft at 3000 ft (~900 m), 30-40 NM. Endurance: ≥96 h in standby, ≥8 h in active operation.

AIS-SART: message content

The AIS-SART transmits AIS message 14 (safety-related broadcast) on AIS channels 1 (161.975 MHz) and 2 (162.025 MHz) alternately, with an MMSI in the 970xxxxxx range (digits 4-6 are the device serial). It reports position every minute for ≥96 h in standby and shows as a target on ARPA/ECDIS of any ship with an AIS receiver within VHF range (typically 5 NM from the surface, more from aircraft). Especially useful in radar-cluttered areas (ports, bays) where a radar SART can be lost among coastal returns.

Portable VHF: specific requirements (MSC.149(77))

SOLAS III/6.2.1 plus MSC.149(77) require: minimum 3 units on passenger ships and on cargo ships ≥500 GT; 2 units on cargo ships 300-500 GT; one extra recommended per survival craft. Distinctive colour (yellow or orange), positive buoyancy, watertight to 1 m for 1 h, display readable underwater. Sealed primary battery (distinctive colour, sealed, visible expiry) for emergency use with ≥8 h endurance at rated power and a 1:1:8 duty cycle (TX/RX/standby); a separate rechargeable battery, distinguishable, for drills and training.

Abandon-ship activation sequence