Volcanic Ash Advisory Center (VAAC)

Volcanic ash clouds often contain large amounts of silicate material, which poses very serious problems for aircraft engines. During flight, the temperature of aircraft engines can reach 800 to 1500 degrees Celsius. When silicate enters the aircraft engine, it can become molten or semi-molten, and stick to the turbine blades in the turbine chamber, obstructing the normal flow of combustion gas. In severe cases, it can even cause the engine to stop (Flameout).

During the 1982 eruption of Galunggung, the British Airways Flight 9 incident occurred, where volcanic ash caused all four engines to flame out; fortunately, a safe landing was eventually made. In 1989, KLM Royal Dutch Airlines Flight 867 sucked in a large amount of volcanic ash due to the eruption of Mount Redoubt, which also caused all engines to flame out, but thankfully a forced landing was successful.

To avoid the damage caused by volcanic ash to aircraft, information regarding volcanic ash is indispensable information for airlines and air traffic management authorities. The International Civil Aviation Organization (ICAO) collaborated with the World Meteorological Organization (WMO) to establish the framework for international air route volcanic ash observation in 1993.

The Volcanic Ash Advisory Center (VAAC) is a meteorological center designated by regional air navigation agreements, responsible for providing information to meteorological watch offices, area control centers, flight information centers, world area forecast centers, and the international flight weather information database regarding the horizontal and vertical distribution and forecast movement of volcanic ash in the atmosphere after an eruption.

In this system, the responsibility of the Volcanic Ash Advisory Centers (VAACs) is to monitor volcanic eruptions within their designated areas and provide information on the position and movement of volcanic ash clouds. Under this framework, nine Volcanic Ash Advisory Centers have been designated: Anchorage, Buenos Aires, London, Montreal, Darwin, Tokyo, Toulouse, Washington, and Wellington. Among them, the East Asia and Northwest Pacific regions are the responsibility of the Tokyo Volcanic Ash Advisory Center.

"VAAC Coverage" by ICAO - http://www.icao.int/anb/iavwopsg/VAAC06.ppt. Licensed under Public Domain via Wikimedia Commons.

The website of the Tokyo Volcanic Ash Advisory Center introduces the VAAC data format, VAAT (Volcanic Ash Advisory Text). Summarized below:

FVFE01: Header information VA ADVISORY: Volcanic Ash Information DTG: Issue Time VAAC: Center issuing the information VOLCANO: Volcano name and number PSN: Latitude and longitude of the volcano AREA: Country where the volcano is located SUMMIT ELEV: Summit elevation ADVISORY NR: Issue series number INFO SOURCE: Information source AVIATION COLOUR CODE: Aviation Colour Code (Not used by Tokyo VAAC, so NIL) ERUPTION DETAILS: Eruption information (Time and details of the volcanic eruption) OBS VA DTG: Time volcanic ash was observed OBS VA CLD: Observed volcanic ash information (Presence of ash, coverage area, ash altitude, movement direction, movement speed. If no ash is detected, upper wind information is provided) FCST VA CLD: Volcanic ash dispersion forecast (Forecast area 6, 12, 18 hours after observation) RMK: Remarks (NIL if none) NXT ADVISORY: Time of next issue

Let’s take a look at the latest issued information. There are more than ten entries in a single day. For example, the VAAT for Russia’s Shiveluch volcano from this morning:

Volcanic Ash Advisory Text FVFE01 RJTD 172309 Tokyo RJTD March 17, 23:09 VA ADVISORY DTG: 20150317/2309Z Issue time March 17, 23:09, Local time March 18, 08:09 VAAC: TOKYO Tokyo Volcanic Ash Advisory Center VOLCANO: SHIVELUCH 300270 Shiveluch Volcano, code 300270 PSN: N5639E16122 Volcano coordinates AREA: RUSSIA Russia SUMMIT ELEV: 3283M Volcano elevation 3283 meters ADVISORY NR: 2015/97 Issue number 2015/97 INFO SOURCE: MTSAT-2 UHPP Information source is MTSAT-2 satellite, also known as Himawari-7 weather satellite, and Petropavlovsk-Kamchatsky Airport AVIATION COLOUR CODE: NIL ERUPTION DETAILS: VA AT 20150317/2205Z FL170 EXTD NE MOV 21KT REPORTED March 17, 22:05 Eruption Altitude FL170 Extended to Northeast 21 knots speed OBS VA DTG: 17/2215Z Observation time March 17, 22:15 OBS VA CLD: VA NOT IDENTIFIABLE FM SATELLITE DATA WIND FL170 220/19KT Ash not identifiable from satellite data. FL170 altitude upper wind Direction 220 Speed 19 knots FCST VA CLD +6 HR: NO VA EXP Forecast 6 hours later: None FCST VA CLD +12 HR: NO VA EXP Forecast 12 hours later: None FCST VA CLD +18 HR: NO VA EXP Forecast 18 hours later: None RMK: WE WILL ISSUE FURTHER ADVISORY IF VA IS DETECTED IN SATELLITE IMAGERY. Will issue further advisory if ash is captured by satellite NXT ADVISORY: NO FURTHER ADVISORIES= No further issue information

Additionally, VAACs issue several types of graphical information, such as the Volcanic Ash Graphic Information (VAGI)

Volcanic Ash Dispersion Forecast Chart (VAG)

Area Dispersion Forecast Chart (VAGFN)

Timed Dispersion Forecast Chart (VAGFNR)

There are not many symbols in the charts, and they are easy to understand, so I won’t go into detail here.

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