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.