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Erupting volcano

Volcanic Ash Advisory

Volcanic ash is composed of fine pulverized rock and accompanied by a number of gases which are then converted into droplets of sulphuric acid and other substances. This constitutes a serious threat to aircraft operations primarily due to the effect these corrosive gases and abrasive particles have on engines and airframe.

In addition to loss of engine performance due to glass like deposits in the engine causing flame-out, ash effects may include instrument and radio failure, visibility problems and damage to other external flying components as well as contamination of the aircraft interior.

In view of recent events caused by the eruption of Eyjafjallajokull in Iceland in 2010 and the very nervous reaction by some Aviation Authorities we felt it was necessary to pay more attention to this phenomena and list all Volcanic Ash Advisory Centers here.

Worldwide Volcanic Ash Advisory Centers

There are nine (9) VAACs established in the world and listed below. Clicking them will open the site in a new window.

• London, UK • Toulouse, France • Montreal, Canada
• Anchorage, US • Washington, US • Buenos Aires, Brazil
• Darwin, Australia • Wellington, New Zealand • Tokyo, Japan

The Volcanic Ash Advisory Centers are part of an international system set up by the International Civil Aviation Organization (ICAO) called the International Airways Volcano Watch (IAVW).


The IAVW comprises observations of volcanic ash from volcano observatories and other organizations, satellites and aircraft in flight, the issue of warnings in the form of NOTAM and SIGMET messages and, since the mid 1990s, the issue of volcanic ash advisory messages from the Volcanic Ash Advisory Centers identifying areas of volcanic ash and their predicted movement.

Effects of Volcanic ash

Airplanes built by homebuilders usually do not fly near areas of volcanic activity (we hope) but should you find yourself near a volcano you may expect a number of effects from the ash:

  • The appearance of a fine dust or haze in the cabin and some dust settlement
  • A sulfurous or acid smell entering in the cockpit
  • Fluctuations in indicated airspeed from partial or complete blockage of the pitot tube / static system
  • Engine surges or power fluctuations as ash will block the air intakes or even enters the engine
  • Aircraft with jet or turbine engines may see a light effect near the intakes
  • St Elmo's fire due to impact of electrical charged particles on the aircraft surface, particularly visible at night

The actions you may take to counter these effects are: descent, reverse track, use oxygen and reduce engine power. But the best remedy is to stay away from these areas!

Written by EAI.

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