Now I don't know

I don't know

I don't know where I'm gonna go

When the volcano blow

— Jimmy Buffett

There are more volcanoes out there than most of us even realize.

The highest concentration of active volcanoes lies around the rim of the Pacific Ocean, the so-called "ring of fire", which stretches northwards, more or less continuously, along the western edge of South and North America, across the Aleutian and Kurile Island chains, down through Kamchatka, Japan and the Philippines and across Indonesia, Papua New Guinea and New Zealand to the islands of the South Pacific. Other active regions are to be found in Iceland, along the Great Rift Valley in Central and East Africa, and in countries around the Mediterranean. This distribution is shown on the map provided as the frontispiece.


What does a volcanic eruption look like?

Well, it varies.

Ranges from explosive eruptions spewing volcanic ash to slow lava flows.

Explosive types of reactions are the ones of concern to aviation.

Can have direct impacts on aircraft and aerodromes.


Are all volcanoes monitored?

Short Answer: No

The cost of actively monitoring all volcanoes in the world is not realistic.

Volcanoes can erupt with little or no warning even if they have not erupted for hundreds of years.

Nine volcanic ash advisory centers provide advisory information through issuing SIGMETs for active volcanic ash.

No matter how sophisticated an observation or forecast is, there is no definitive assurance on how the volcanic ash will behave in the atmosphere.


Intro to Ash

What is volcanic ash?

Mainly sharp-edged, hard glass particles and pulverized rocks.

The melting temperature is below the operating temperature of turbine engines.

Gases which are corrosive to airframes and hazardous to health.


Effects to the Airframe - Short Term

Malfunction or failure of engines including reduction, complete loss of thrust, flame-out, failure of electrical, pneumatic, and/or hydraulic systems.

Blockage of pitot and static sensors resulting in unreliable airspeed indications and erroneous warnings.

Windscreens rendered partially or completely opaque.

Contamination of cabin air requiring crew use of oxygen masks.

Volcanic ash contains particles whose melting point is below modern turbine engine burner temperature; these particles then fuse in the turbine section reducing the throat area and its efficiency leading to engine surge and possibly flame-out.

Flight crew manoeuvring for volcanic cloud avoidance which may potentially conflict with other aircraft in the vicinity.



Effects to the Airframe - Long Term

Erosion of external aircraft components.

Potential short circuits leading to a wide range of aircraft system failures and/or anomalous behaviour.

Volcanic Ash can cause degraded airport conditions ranging from reduced braking action to runway closure.

Aircraft ventilation and pressurization systems becoming heavily contaminated.



Impacts on Airframe Examples - BAW9

In 1982 British Airways 9 had 4 engines flameout at 37,000 over Indonesia en route from Heathrow to Auckland.

Volcanic ash clogged all 4 engines with debris, causing all four of the jet’s engines to stop.

Repeated attempts were made to restart the engines before they were able to regain some function.

Their windscreen had been sandblasted by the ash from Mt. Galunggung and with limited visibility made a successful instrument landing in Jakarta.



Where are reports generated from?

Various Sources:


Worldwide series of reporting stations

Satellite data

Seismic-, infrasound- and lightning observation



How big/wide can an ash cloud be? What can the spread look like? How does wind impact it?

How far can it drift from source?


How wide of a swath do I sterilize?

What altitude is the ash cloud at?

Possibly visible in satellite images



Eyjafjallajökull - An Example of Impacts

7-day shutdown of much of Europe's air traffic.

Impacted 10 million passengers.

Estimated cost between €1.5 billion and €2.5 billion.

Delays, cancellations and re-routes.


How do I read a Volcanic Ash Advisory?

What does all this information mean?

> Interpret where the advisory is issued by plotting the latitude and longitude coordinates.

> The most important information in a SIGMET is knowing what altitude the ash cloud is at along with which way the ash cloud is moving.

> The advisory will also depict the tops and bases of the cloud.


When Dealing with Crews in Ash

Things to remember

Aircraft do not have dedicated Volcanic Ash sensors.

Expect the Unexpected - including deviations whether coordinated or not.

Workload will be greatly increased.

Different companies have different policies for how to handle Volcanic Ash - which may result in one aircraft flying in closer proximity than another. It is up to the crew to decide.


From a controller’s perspective

What can I do?

Be aware of the volcanic weather in your area.

Don’t make the situation worse for the pilot.

Assist the pilot to turnaround and exit the ash cloud.

Pilots are trained to turn around 180 degrees and exit the ash cloud.


How do I Mitigate Volcanic Ash?

And SMS Impacts

Effective SMS should incorporate procedures for continuous monitoring of hazards and risk.

Qualified personnel should establish mitigating actions or halt of affected operations.

Continuous Safety Risk Management is needed beyond initial assessment.


What might a crew report?

• Smoky or acrid odour; could also smell like electrical smoke, burnt dust, or sulphur.

• Haze. Most flight crews, as well as cabin crew or passengers, see a haze develop within the aircraft cockpit.

• Changing engine conditions including but not limited to: surging, flameouts, and engine temperature fluctuation.

• Fluctuating airspeed; this can occur if ash clogs pitot tubes.

• Pressurization, including possible loss of cabin pressure.

• Static discharges.

Want to know more? Have a look at the following ICAO Documents:

(Note: An ICAO Secure Portal Login is required to access these documents)

Doc 9974

Flight Safety and Volcanic Ash

Doc 9691

Manual on Volcanic Ash, Radioactive Material and Toxic Chemical Clouds

Doc 9766

Handbook on the International Airways Volcano Watch (IAVW) — Operational Procedures and Contact List