VAAC
VAAC identifies the Volcanic Ash Advisory Centre responsible for the advisory. In the documented example, the issuing center is Anchorage.
VOLCANIC ASH ADVISORY DECODER
Decode a Volcanic Ash Advisory
Decode Volcanic Ash Advisories into volcano, VAAC, location, ash height, movement and forecast ash-cloud information.
Try an example:
VOLCANIC ASH ADVISORY
What is a Volcanic Ash Advisory?
A Volcanic Ash Advisory (VAA) provides aviation information about volcanic activity and ash that may affect flight operations. The advisory identifies the volcano and issuing Volcanic Ash Advisory Centre, then reports available eruption and ash-cloud information together with forecasts.
Decoded fields are shown alongside the original advisory so names, coordinates, times, altitudes and forecast text can be checked against the coded message.
ADVISORY FORMAT
How to read a Volcanic Ash Advisory
The documented advisory format begins with message and issue information, followed by the VAAC, volcano identification and location. It then provides information about the eruption, observed ash and forecast ash-cloud positions.
Volcano and identifier
The VOLCANO field gives the volcano name and can include an associated identifier. These are presented separately when they are available in the documented format.
Volcano location
LOCATION gives the volcano coordinates. Latitude and longitude are decoded while the original coordinate text remains visible.
Area and summit elevation
The advisory can identify the geographic area and the volcano summit elevation. The documented format provides summit elevation in feet and metres.
Advisory number
The advisory number identifies the year and sequence of the message, making successive advisories for the same volcanic event easier to distinguish.
Information source and color code
INFORMATION SOURCE records the basis for the advisory. AVIATION COLOR CODE is retained as reported, including cases where no color code is given.
ERUPTION DETAILS
Ash height and movement
The documented eruption-details field can include an approximate eruption time, an estimated ash height expressed as a flight level, and movement direction and speed.
These values are separated when they match the documented advisory form. The complete eruption-details text remains available for reference.
OBSERVED ASH
Observed volcanic ash cloud
OBS ASH DATA/TIME records the time associated with the observed ash information. OBS ASH CLOUD describes the observed ash cloud and its reported geographic extent.
Ash-cloud geometry is retained as written in the advisory. The page does not convert that text into a more detailed geometric interpretation where the available documentation does not establish the required syntax.
ASH FORECAST
Volcanic ash forecast periods
The documented VAA format contains forecast ash-cloud information for +6, +12 and +18 hours. Each forecast field describes the expected ash-cloud position or extent for its forecast horizon.
Forecast descriptions remain in their original operational form rather than being converted into unsupported geometry.
EXAMPLE
Volcanic Ash Advisory example
VOLCANO: CHIKURACHKI, 900-36
The documented example identifies Chikurachki volcano at N5019 E15527, with a summit elevation of 7,674 feet (2,339 metres). The information source is satellite and the aviation color code is reported as NOT GIVEN.
The eruption details report an estimated ash height of FL300 and eastward movement at 75 knots. The advisory then provides observed ash information, +6, +12 and +18 hour forecasts, remarks and the time of the next advisory.
RELATED WEATHER
Related aviation weather decoders
Volcanic ash can also be reported in other aviation weather products. The SIGMET Decoder covers the SIGMET formats documented on that page. Tropical cyclone advisories are handled separately by the Tropical Cyclone Advisory Decoder.
DECODER COVERAGE
Current decoder coverage
This decoder covers the Volcanic Ash Advisory format represented by the documented FAA example, including volcano information, eruption details, observed ash and the +6, +12 and +18 hour forecast fields. Other international variants may use forms that are not interpreted here.