When planning NAVTEX services, Administrations should obtain guidance at an early stage from IMO, through its NAVTEX Coordinating Panel. This may be particularly important when installation of new stations and/or purchase of new equipment is under consideration.
International NAVTEX services on 518 kHz
When planning an International NAVTEX service it is essential to appreciate the high level of national and international coordination required. The central principles which should be borne in mind are as follows:
- All NAVTEX stations are part of the strategic infrastructure of both the GMDSS and WWNWS (World-Wide Navigation Warning Service).
- It is essential for the efficiency and effectiveness of the service that a minimum number of stations are used. This may require national Administrations to either share facilities or promulgate information provided by Administrations of other nations.
- Each station contributes to the overall service in a coordinated way, bearing in mind the geographical area covered by each station and the effective coordination and control of information to be transmitted.
- The two basic areas which must be defined when establishing a NAVTEX station are the NAVTEX coverage area and the NAVTEX service area. Each station will provide all the information for a particular NAVTEX service area. The boundaries of the NAVTEX service area must be wholly contained within the coverage area, and must not overlap with adjacent NAVTEX service areas (see figure).
- National Administrations seeking to establish NAVTEX services shall undertake preliminary discussions with the NAVAREA Coordinator, METAREA Coordinator and neighbouring Administrations prior to formal application to IMO through the IMO NAVTEX Coordinating Panel. These discussions shall consider the most appropriate NAVTEX service area boundaries, possible geographical locations for transmitter sites to ensure optimal coverage and links with Information Providers
- The range of a NAVTEX transmitter depends on the transmitted power and local radio propagation conditions. The actual range achieved shall be adjusted to the minimum required for adequate reception in the specified NAVTEX service area, taking into account the needs of ships approaching from other areas. Experience indicates that the required range of 250 to 400 nautical miles will normally be attained by transmitted power of no more than 1 kW during daylight with a 60% reduction during night conditions.
- After the choice of transmitter sites, the main need for coordination lies in the assignment of B1 transmitter identification characters (time schedules) and the agreement of proposed NAVTEX service areas (if appropriate). Preliminary discussions between national Administrations seeking to establish or amend NAVTEX services and neighbouring Administrations shall be coordinated by the NAVAREA Coordinator prior to formal application for a B1 transmitter identification character. Throughout the process the IMO NAVTEX Coordinating Panel is available to advise and liaise on the final limits of NAVTEX service areas if these cannot be agreed locally.
- The IMO NAVTEX Coordinating Panel will only allocate B1 transmitter identification characters after the NAVTEX service areas have been agreed.
- Once a NAVTEX transmitter has been declared operational, if a national Administration wishes to:
- move the transmitter site; and/or
- amend the limits of its NAVTEX service area, then the whole coordination process outlined above must be repeated, keeping the NAVTEX Coordinating Panel informed at all times.
- A National NAVTEX Coordinator shall be established to oversee the operation of the NAVTEX services established by each national Administration.