It should also be emphasized that SOLAS provides (in regulation IV/4.1.7) that a ship must be capable of transmitting and receiving MSI.
2.1.2 Based on the SOLAS provisions, a list of MSI categories can be drawn up:
.1 categories of MSI that exist now:
- navigational warnings (cf. A.706 (17), IHO documents and COMSAR/Circ.15). Some of these may be used for SAR operations: see below 2.3. This category includes messages related to acts of piracy or armed robbery;
- meteorological bulletins and forecasts (cf. WMO documents and COMSAR/Circ.15);
- danger messages broadcast by ships (cf SOLAS regulation V.2).
.2 categories of MSI that can be envisaged in the future:
- the only category of MSI currently foreseeable might consist of services for correcting electronic charts.
2.1.3 Lastly, it will be recalled that the SafetyNET, Inmarsat and NAVTEX services2 are the only means of shore-to-ship broadcasting of MSI in the GMDSS.
2.2 A distress alert cannot be MSI.
In the light of the above, a distress alert is therefore never MSI, even when transmitted by SafetyNET or NAVTEX3. The IMO documents mentioned in annex 2 and the International SaferyNET Manual should be amended to take this into account.
2.3 Some SAR communications which are not distress alerts take the form of MSI of the navigational warning type
This situation, which existed even before the GMDSS came into operation, is covered in resolution A.706 (17) and circular COMSAR/Circ.15.
There are two cases which it is important to differentiate:
.1 Navigational warnings transmitted at the request of an MRCC for ships which are missing (4.2.1.3.7 of A.706 (17), 3 of COMSAR/Circ.15 and 9.1.5.2 of the NAVTEX Manual). It is true that this type of navigational warning may seem similar to an alert message. However, it is completely different in nature (see 2.1.1 above).
2 And possibly NBDP (narrow band direct print) systems on decametric waves (HF).
3 The NAVTEX Manual (IMO-951E) states in 9.1.5.1 that NAVTEX transmission is not suitable for distress traffic and thus only the initial alert should be transmitted by this means.
