April 2010 European Airspace Closure: The Eyjafjallajökull Eruption

From April 14–25, 2010, the eruption of Eyjafjallajökull volcano in Iceland caused the largest air traffic shutdown since WWII.

Mechanism

• Explosive phreatomagmatic eruption injected fine silicate ash to 9–11 km (30–36k ft) — jet cruise altitudes.
• Prevailing westerlies advected ash cloud across UK, Scandinavia, N. Europe, C. Europe, reaching Russia.
• Ash melts in turbine engines (1400°C+), re-solidifies on blades → engine flameout/failure. Also abrades windscreens, pits compressor blades, clogs pitot tubes.

Impact

• 100,000+ flights cancelled over 8 days.
• 10 million passengers stranded.
• $1.7B+ airline revenue loss (IATA); broader economic losses ~$5B.
• Major hubs closed: LHR, CDG, FRA, AMS, MAD, CPH, OSL, ARN.

Response Evolution

Initial "zero tolerance" (any ash = closure) shifted to concentration thresholds (ICAO/VAAC/EASA): Low (<2 mg/m³), Medium (2–4), High (>4). Airlines submitted safety cases for Medium. Enabled phased reopening.

Lessons

• Volcanic Ash Advisory Centers (VAACs) critical.
• Need for airborne ash sensors (not just satellite models).
• Airline safety cases + regulator flexibility = resilience.
• 2011 Grímsvötn eruption managed with new protocol — minimal disruption.