4.2 The four types of navigational warnings are:

  4.2.1.1 NAVAREA warnings are concerned with the information detailed below which oceangoing mariners require for their safe navigation. This includes, in particular, new navigational hazards and failures of important aids to navigation as well as information which may require changes to planned navigational routes.

  4.2.1.2 Coastal warnings are broadcast by the International NAVTEX service, or by the International SafetyNET service when implemented in lieu of NAVTEX. They are not normally rebroadcast as NAVAREA warnings unless deemed of such significance that the mariner should be aware of them before entering a NAVTEX service area. The National Coordinator will evaluate the significance of the information for consideration as a NAVAREA warning while the NAVAREA Coordinator will make the final determination.

  4.2.1.3 The following subjects are considered suitable for broadcast as NAVAREA warnings. This list is not exhaustive and should be regarded only as a guideline. Furthermore, it presupposes that sufficiently precise information about the item has not previously been disseminated in a Notice to Mariners:

• .1 casualties to lights, fog signals, buoys and other aids to navigation affecting main shipping lanes;

• .2 the presence of dangerous wrecks in or near main shipping lanes and, if relevant, their marking;

• .3 establishment of major new aids to navigation or significant changes to existing ones, when such establishment or change might be misleading to shipping;

• .4 the presence of large unwieldy tows in congested waters;

• .5 drifting hazards (including derelict ships, ice, mines, containers, other large items over 6 metres in length, etc.);

• .6 areas where search and rescue (SAR) and anti-pollution operations are being carried out (for avoidance of such areas);

• .7 the presence of newly discovered rocks, shoals, reefs and wrecks likely to constitute a danger to shipping, and, if relevant, their marking;

• .8 unexpected alteration or suspension of established routes;

• .9 cable or pipe-laying activities, the towing of large submerged objects for research or exploration purposes, the employment of manned or unmanned submersibles, or other underwater operations constituting potential dangers in or near shipping lanes;

• .10 the establishment of research or scientific instruments in or near shipping lanes;

• .11 the establishment of offshore structures in or near shipping lanes;

• .12 significant malfunctioning of radionavigation services and shore-based maritime safety information radio or satellite services;

• .13 information concerning events which might affect the safety of shipping, sometimes over wide areas, e.g. naval exercises, missile firings, space missions, nuclear tests, ordnance dumping zones, etc. It is important that where the degree of hazard is known, this information is included in the relevant warning. Whenever possible such warnings should be originated not less than five days in advance of the scheduled event and reference may be made to relevant national publications in the warning;

• .14 acts of piracy and armed robbery against ships;

• .15 tsunamis and other natural phenomena, such as abnormal changes to sea level;

• .16 World Health Organization (WHO) health advisory information; and

• .17 security related requirements^footnote.

  4.2.2.1 Sub-area warnings broadcast information which is necessary for safe navigation within a Sub-area. They will normally include all subjects listed in 4.2.1.3 above, but will usually affect only the Sub-area.

  4.2.3.1 Coastal warnings broadcast information which is necessary for safe navigation within areas seaward of the fairway buoy or pilot station, and should not be restricted to main shipping lanes. Where the area is served by NAVTEX, it should provide navigational warnings for the entire NAVTEX service area. Where the area is not served by NAVTEX, it is necessary to include all warnings relevant to the coastal waters up to 250 miles from the coast in the International SafetyNET service broadcast.

  4.2.3.2 Coastal warnings should include at least the subjects in 4.2.1.3.

  4.2.4.1 Local warnings broadcast information which cover inshore waters, often within the limits of jurisdiction of a harbour or port authority. They are broadcast by means other than NAVTEX or SafetyNET, and supplement coastal warnings by giving detailed information within inshore waters.