Volcanic Ash Advisory Centre

What is VAAC?

The Volcanic Ash Advisory Centre system is ICAO's global framework for protecting aviation from volcanic ash — an invisible, engine-destroying hazard. Nine VAACs divide responsibility for the entire planet: Anchorage (North Pacific), Buenos Aires (South America), Darwin (Australia/Southeast Asia), London (Northeast Atlantic/Europe), Montreal (North America), Toulouse (Europe/Africa), Tokyo (Northwest Pacific), Washington (North America/Caribbean), and Wellington (Southwest Pacific).

Each VAAC uses satellite imagery, ground-based sensors, pilot reports, and numerical dispersion models to track ash clouds and forecast their movement up to 18 hours ahead. When an eruption is detected, the VAAC issues Volcanic Ash Advisories (VAAs) and coordinates with Meteorological Watch Offices to trigger volcanic ash SIGMETs. Airlines use these advisories to plan routes that avoid contaminated airspace.

The system was stress-tested repeatedly in 2023-2024: Mount Marapi in Indonesia (December 2023), Popocatepetl in Mexico (multiple eruptions in 2023-2024), Mount Etna/Stromboli dual eruptions in Italy (2024), and the continuing Reykjanes Peninsula eruption sequence in Iceland. Post-Eyjafjallajokull reforms — including ash concentration thresholds and improved engine tolerance data — allowed more proportionate responses than the blanket closures of 2010.

Why It Matters for Airspace Risk

Volcanic ash events can close major airspace corridors with little warning, and unlike conflict-driven closures, they affect airspace purely based on atmospheric conditions that change hourly. VAAC advisories determine which routes are safe and which must be avoided. When volcanic ash overlaps with conflict-driven rerouting corridors — for example, if Icelandic ash blocks North Atlantic routes while Ukraine closures force traffic south — the cascading disruption multiplies. FlySafe monitors active VAAC advisories as a core component of route risk assessment.

Key Facts

• •Nine VAACs cover the entire globe, each responsible for a defined geographic area of volcanic activity monitoring.
• •Volcanic ash can destroy jet engines — even concentrations invisible to the naked eye erode turbine blades and melt onto internal components.
• •Post-2010 reforms introduced ash concentration zones (low/medium/high) replacing the previous binary "ash/no-ash" approach.
• •The London and Toulouse VAACs cover the busiest volcanic ash risk area for transatlantic aviation, including Iceland.
• •VAACs issue forecasts up to T+18 hours, with updates every 6 hours during active eruptions.

Related Terms

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