The World Area Forecast System (WAFS) was established by the ICAO Communications/Meteorology (COM/MET) Divisional Meeting held conjointly with the seventh session of the WMO Commission for Aeronautical Meteorology (CAeM) in Montreal in 1982. The objectives of the system are "to supply meteorological authorities and users with forecasts of en-route meteorological conditions in pictorial, alphanumeric and digital form. These objectives are to be achieved in a cost-effective manner through a comprehensive, integrated worldwide, and, as far as is practicable, uniform system".
The meteorological information as regards en-route conditions for pre-flight and in-flight planning and for the selection of organized tracks comprises forecasts of global:
To facilitate computerized processing, the system provides the products under a) to f) in standardized digital format using the gridded binary (GRIB) code (WMO FM 92-IX Ext. GRIB refers) and product g) in the binary universal format for representation of meteorological data (BUFR) code (WMO FM 94-XII Ext. BUFR refers).
The foregoing products are distributed globally by the two world area forecast centres (WAFC), London and Washington by satellite broadcast as part of the ICAO aeronautical fixed service (AFS). WAFS products consist of aeronautical meteorological information of an operational nature. There is therefore an obligation for ICAO to ensure that all ICAO Contracting States have access to all the WAFS data they may need through at least one component of the AFS.
In order to meet growing requirements for operational meteorological (OPMET) information in alphanumeric form, such as aerodrome routine meteorological reports (METAR), aerodrome forecasts (TAF), SIGMET, and special air-reports (special AIREP), character-oriented OPMET information is also disseminated via the satellite broadcasts in real time.
The worldwide satellite communications are provided using four INTELSAT satellites.
The United States provide three INTELSAT services for the distribution of WAFC Washington products over the Americas, Pacific and Eastern Asia, using INTELSAT satellites based over the Atlantic, the Pacific and Indian Oceans. The services provided by the United States are known as the International Satellite Communications System (ISCS).
To meet the requirements for WAFS dissemination in Europe, the EANPG developed a system for the distribution of WAFS data via satellite, as one component of the AFS. Originally the system was intended to serve the ICAO European (EUR) and Middle East (MID) Regions, but it was subsequently extended to serve the Africa-Indian Ocean (AFI) Region and the western part of the ASIA Region. The system is now capable of serving all States in the AFI and MID Regions and the ASIA and EUR States up to about 140° East and is known as the Satellite Distribution System for Information Relating to Air Navigation (SADIS).
SADIS is an operational system dedicated primarily to aeronautical meteorological information in line with ICAO worldwide provisions. WAFS forecasts and OPMET information are disseminated without conflict or delay caused by the dissemination of non-operational data. As an ICAO system forming part of the AFS, it has been designed to meet the worldwide Standards and Recommended Practices (SARPs) promulgated in ICAO Annex 3 — Meteorological Service for International Air Navigation and Annex 10 — Aeronautical Telecommunications. This ensures full availability of the service and the largely error free transmission of all information required for pre-flight planning. WAFS GRIB and BUFR forecasts will be backed up, with WAFC London and WAFC Washington products being interchangeable.
SADIS provides a point to multi-point service on a 24-hour basis via satellite. The SADIS uplink is situated at the Cable & Wireless hub at Whitehill Earth Station, north of Oxford in the United Kingdom. The WAFS data is provided from WAFC London in the United Kingdom Met Office (referred to as “Met Office”), Exeter, via terrestrial 64 kilobits per second (kbps) lines and are uplinked from the hub at Whitehill to the INTELSAT satellite 904 located over the Indian Ocean at 60°E. The OPMET data is provided by the National Air Traffic Services (NATS) SADIS Gateway facility (supplied by NetSys) at Swanwick near Southampton. Data from the Gateway is transmitted via a switched virtual circuit (SVC) to the Met Office for onward promulgation via the aforementioned terrestrial leased lines to Whitehill. The data are downlinked via a global beam to users anywhere in the AFI and MID Regions and in the ASIA and EUR Regions as far eastwards as 140°E.
SADIS User GuideAnguilla | Cayman Islands | Haiti | St. Martin |
Antigua | Cuba | Jamaica | Sint Maarten |
Aruba | Curacao | Martinique | St. Vincent |
Azores | Dominican Republic | Montserrat | Tortola |
Bahamas | Dominica | Puerto Rico | Trinidad & Tabago |
Barbados | Grenada | St. Kitts | |
Bermuda | Guadeloupe | St. Lucia |
Belize | EL Salvador | Honduras | Panama |
Colombia | Ecuador | Mexico | |
Costa Rica | Guatemala | Nicaragua |
Argentina | Chile | Paraguay | Uruguay |
Bolivia | French Guiana | Peru | Venezuela |
Brazil | Guyana | Suriname |
Canada | United States |
Niger |
England |
American Samoa | Fiji | New Caledonia | Vanuatu |
Australia | French Polynesia | Niue Island (Korea) | Hawaii |
Brunei | Indonesia | Papua New Guinea | Caroline Island |
Japan | Peoples Republic of China | China (Mainland) | Johnson Island |
Philippines | Cook Island | Kiribati | Republic of Korea |
North Korea | Mariana Islands | Samoa | East Timor |
Marshall Islands | Solomon Islands | Easter Island | Nauru |
Tonga |
Malaysia | Thailand | Vietnam |