How Flying Works
Why Does Volcanic Ash Ground Flights? The Real 1982 Incident
Whenever a major eruption disrupts flights, it can look like excessive caution from the ground — ash doesn’t seem like it should be able to stop a jet engine. One real incident from 1982 shows exactly why airlines take it as seriously as they do, and it very nearly ended in catastrophe.
British Airways Flight 9, 24 June 1982
A Boeing 747-236B, registration G-BDXH, was flying from Kuala Lumpur to Perth under Captain Eric Moody when it flew into an ash cloud from the eruption of Mount Galunggung in Indonesia. The cloud was invisible on the aircraft’s weather radar, which is built to detect water and ice, not fine volcanic particles — and at night, invisible to the naked eye as well. Within minutes, all four engines flamed out, one after another, leaving the aircraft powerless at 37,000 feet.
How the crew actually got the engines back
With no engine power, the aircraft became, in effect, a very large glider, descending roughly 15 kilometers of distance for every kilometer of altitude lost. That descent turned out to be the reason the crew survived: as the 747 glided lower, it descended out of the ash cloud and into cooler air. The molten ash that had coated the turbine blades inside each engine — cooling into a hard glass layer that disrupted airflow and caused the flameouts in the first place — began to cool further still, crack, and flake away now that it was no longer being fed fresh molten ash. That was enough for the crew to successfully restart the engines one at a time as the aircraft continued its descent, and they landed the aircraft safely in Jakarta on three functioning engines. All 263 people aboard survived.
What actually changed because of this flight
BA9 became the incident that made the aviation industry treat volcanic ash as a genuine, first-order hazard rather than a minor nuisance. It led directly to the creation of the global Volcanic Ash Advisory Centre (VAAC) network — a coordinated system of monitoring centers around the world that tracks volcanic activity and models where ash clouds are moving, issuing the advisories that cause airlines to reroute or ground flights well before any crew would discover the hazard by flying into it. The caution that can look excessive from the ground is a direct, traceable response to what happened over Indonesia in 1982 — and to how close it came to a very different outcome.
Sources & Further Reading
Common Questions
Frequently Asked Questions
Why can't weather radar just detect volcanic ash and avoid it?
Standard weather radar is built to detect water droplets and ice in clouds, not the fine mineral particles that make up volcanic ash — the crew of BA9 flew directly into a genuine ash cloud that was invisible on their radar and, at night, invisible to the eye as well.
How exactly does ash destroy a jet engine mid-flight?
Volcanic ash is essentially fine silicate rock. Inside a running jet engine, combustion temperatures are high enough to melt it, and the molten ash then coats the turbine blades and cools into a hard glass layer as it moves further from the heat — disrupting airflow badly enough that all four of BA9's engines flamed out in sequence.
How did the crew manage to restart the engines?
As the aircraft glided down without power, it descended out of the ash cloud and into cooler air — the glass coating on the turbine blades, no longer being fed by molten ash, cooled further, cracked, and flaked away. That cleared enough of the blockage for the crew to successfully restart the engines one by one before landing.
What changed in aviation because of this incident?
It directly led to the creation of the global Volcanic Ash Advisory Centre (VAAC) network — a coordinated system that tracks volcanic activity and ash cloud movement worldwide and issues the advisories that cause flights to be rerouted or grounded whenever a real ash hazard is identified, rather than relying on individual crews to discover it in flight.