data and animated weather symbols. The BBC used to use Met Office forecasts for all of its output, but on 23 August 2015, it was announced that the BBC would be replacing the Met Office with MeteoGroup, a competing provider, as part of the corporation's legal obligation to provide best value for money for the licence fee payers. The BBC still uses some Met Office data for certain forecasts, particularly severe weather warnings and the Shipping Forecast. World Area Forecast Centre The Met Office is one of only two World Area Forecast Centres or WAFCs, and is referred to as WAFC London. The other WAFC is located in Kansas City, Missouri, and known as WAFC Washington. WAFC data is used daily to safely and economically route aircraft, particularly on long-haul journeys. The data provides details of wind speed and direction, air temperature, cloud type and tops, and other features. Volcanic Ash Advisory Centre As part of its aviation forecast operation the Met Office operates the London Volcanic Ash Advisory Centre (VAAC). This provides forecasts to the aviation industry of volcanic ash clouds that could enter aircraft flight paths and impact aviation safety. The London VAAC, one of nine worldwide, is responsible for the area covering the British Isles, the north east Atlantic and Iceland. The VAAC were set up by the International Civil Aviation Organization (ICAO), an agency of the United Nations, as part of the International Airways Volcano Watch (IAVW). The London VAAC makes use of satellite images, plus seismic, radar and visual observation data from Iceland, the location of all of the active volcanoes in its area of responsibility. The NAME dispersion model developed by the Met Office is used to forecast the movement of the ash clouds 6, 12 and 18 hours from the time of the alert at different flight levels. Air quality The Met Office issues air quality forecasts made using NAME, the Met Office's medium-to-long-range atmospheric dispersion model. It was developed as a nuclear accident model following the Chernobyl accident in 1986, but has since evolved into an all-purpose dispersion model capable of predicting the transport, transformation and deposition of a wide class of airborne materials. NAME is used operationally by the Met Office as an emergency response model as well as for routine air quality forecasting. Aerosol dispersion is calculated using the United Kingdom Chemistry and Aerosols model. The forecast is produced for