Why Aircraft and Ash Don’t Mix: The Fallout from Volcanic Eruption

14 April 2010 (Last Updated April 14th, 2010 18:30)

Iceland's erupting volcano is creating transport chaos across the UK and northern Europe. We explain why so many flights are being grounded.

Why Aircraft and Ash Don’t Mix: The Fallout from Volcanic Eruption

Until recently, the stories of two aircraft that almost became offerings to the great volcano were relatively forgotten. And maybe for the airline industry that is a good thing. Volcanos are probably one of the biggest reminders to industry that there is simply no playing God.

While machines to make runways and aircraft safe during snow have been developed, along with instruments to detect the slightest shift in weather patterns, it seems little can be done about the mighty volcano. Flights will remain cancelled and some airports closed until the plume of crusty ash drifts away from Northern Europe. Meanwhile, passengers on the ground will consider themselves lucky they did not share the fate of passengers on near-fatal flights in 1982 and 1989, who almost fell
victim to a volcano.

1982 ash cloud encounter

"It was very frightening, all the engines stopped for about 15 minutes and we didn't know what was happening," Captain Eric Moody, who was pilot of the London to Auckland 263-passenger British Airways Boeing 747 that flew through a volcanic ash cloud in 1982, told Sky News. "We glided the aircraft for about 80nm and went down 37,000ft to about 12,000ft."

"The Eyjafjallajökull volcano in Iceland erupted on 14 April, releasing a large plume of volcanic ash over northern Europe."

Mount Galunggung in Java, Indonesia, did not claim its 263 victims that day. The aircraft came out of the plume and was able to restart after the ash cleared from its engines. It was, however, one of the first real wake-up calls the aerospace industry had received regarding volcanic ash and its affect on flight. It led to a number of training initiatives into the detection of ash plumes – how to tell them apart from normal clouds, visually and on radar, what they smell like in cabin air and how to spot electrical friction on the surfaces of the craft.

Often an ash plume can appear out of nowhere. It can take less than 30 minutes for a plume of ash to travel 90,000ft into the atmosphere – and volcano eruptions aren't the most predictable occurrences in the natural world.

KLM's 1989 747 flight from Amsterdam to Anchorage in Alaska, dropped more than two miles after hitting a plume from Mount Redoubt in Alaska. Pilots of that flight were also able to get the engines restarted but the aircraft was seriously damaged.

Weighing up the risks

Between 1980 and 2000, it is believed that more than 80 aircraft flew into volcanic ash clouds – most suffered wear to the engines and other equipment, but not life threatening damage.

Despite this, Airbus suggests that it would be ludicrous for any airline to consider flying through volcanic ash. "Flying through an ash cloud should be avoided by all means due to the extreme hazard to the aircraft," it says. Here are some of the reasons why:

  • Damage can occur to aircraft surfaces, windshields and powerplants.
  • Aircraft ventilation, hydraulic, electronic and air data systems can be contaminated.
  • Aircraft can suffer partial or total engine power loss if volcanic ash is taken in by the engine.
  • Aircraft can simultaneously lose power to all engines as parts are eroded due to the abrasive ash particles.
  • The weather radar cannot detect an ash plume.
  • Other aircraft components including windshields, forward cabin windows, navigation and landing lights covers, wing, stabilizer and fin leading edges, engine nose cowls and thrust reversers and pitot and static probes can also become damaged.
"Flights will remain cancelled and some airports closed until the plume of crusty ash drifts away from Northern Europe."

2010 Icelandic eruption

The Eyjafjallajökull volcano in Iceland erupted on 14 April, releasing a large plume of volcanic ash over northern Europe. The European air safety body, Eurocontrol, said the cloud of ash had reached 55,000ft and was expected to move through northern UK and Scotland by 13.00 BST on 15 April. This was the second volcanic eruption in the area within a month.

Brian Flynn, assistant head of operations of the Eurocontrol central flow management unit, told the BBC: "As it moves toward the Netherlands and Belgium it will dissipate and lose intensity, like any weather phenomenon. But we don't know what the extent of it will be."

"[The UK's air traffic control service] Nats has good cause to be very cautious about this as in 1982 a British Airways jumbo had the unnerving experience of having all four engines shut down as it flew through a plume of volcanic ash."

A BAA spokesman said: "Passengers intending to fly today are asked to contact their airline for further information and should expect disruption in the coming hours.