The Volcanic Ash Advisory Centers (VAAC) are groups of experts and government-funded bodies to montor volcanic ash clouds all over the planet in real time. As Europe experienced in April 2010, volcanic ash clouds are hazardous for aircraft and must be avoided to fly through, even if that means cancellation of flights.
As of 2010, there are 9 VAAC located in different areas and each focussing monitoring a certain section of the globe:
- VAAC London: northern Europe / Atlantic incl. Iceland
- VAAC Toulouse: southern Europe, Mediterranean and Africa
- VAAC Tokyo: East Asia incl. Kamchatka and Japan
- VAAC Darwin: SE Asia & SE Pacific incl. Indonesia and PNG
- VAAC Wellington: S Pacific
- VAAC Anchorage: Alaska
- VAAC Washington: Central America and most of N and parts of S America
- VAAC Montreal: Canada and N Polar region
- VAAC Buenos Aires: South America
The normally busiest VAAC are Tokyo and Darwin, thanks to the activity of the very active volcanoes in Kamchatka, Japan, and in SE Asia.
The least busiest VAAC are normally London, Toulouse and Montral, but when Eyafjallajökull volcano erupted in 2010 and repeatedly closed European Airspace, they certainly had intense work...
The detection of ash clouds is mainly done by analyzing satellite data, collecting pilot reports as well as ground information. The forcast of ash cloud development combines this information with meteorologic data and models.
Each time, a new eruption producing a siginificant ash cloud (rising more than a kilometer or so) is detected, a Volcanic Ash Advisory (VAA) - a short report in standardized format about the ash cloud, its location and likely development - is issued and transmitted to air control centers world wide and can also reach aircraft in flight with almost no delay.
The data is publicly available as well, and the VAC are a useful tool to monitor volcanic eruptions.