Air travel disruption after the 2010 Eyjafjallajökull eruption

In response to concerns that volcanic ash ejected during the 2010 eruptions of Eyjafjallajökull in Iceland would damage aircraft engines, the controlled airspace of many European countries was closed to instrument flight rules traffic, resulting in what at the time was the largest air-traffic shut-down since World War II. The closures caused millions of passengers to be stranded not only in Europe, but across the world. With large parts of European airspace closed to air traffic, many more countries were affected as flights to, from, and over Europe were cancelled.

After an initial uninterrupted shutdown over much of northern Europe from 15 to 23 April, airspace was closed intermittently in different parts of Europe in the following weeks, as the path of the ash cloud was tracked. The ash cloud caused further disruptions to air travel operations in Scotland and Ireland on 4 and 5 May and in Spain, Portugal, northern Italy, Austria, and southern Germany on 9 May. Irish and UK airspace closed again on 16 May and reopened on 17 May.

The eruption occurred beneath glacial ice. The cold water from the melting ice chilled the lava quickly, causing it to fragment into very small particles of glass (silica) and ash, which were carried into the eruption plume. The extremely fine ash particles and the large volume of steam from the glacial meltwater sent an ash plume hazardous to aircraft rapidly high into the upper atmosphere. The presence and location of the plume depended upon the state of the eruption and the winds. The large amount of glacial meltwater flowing into the eruption vent made this eruption so explosive that it ejected its ash plume directly into the jet stream, which was unusually stable and south-easterly. The ash was then carried over Europe into some of the busiest airspace in the world.

The International Air Transport Association (IATA) estimated that the airline industry worldwide would lose (, ) a day during the disruption. IATA stated that the total loss for the airline industry was around US$1.7 billion (£1.1 billion, €1.3 billion). The Airport Operators Association (AOA) estimated that airports lost £80 million over the six-and-a-half days. Over 95,000 flights had been cancelled all across Europe during the six-day airspace ban, with later figures suggesting 107,000 flights cancelled during an 8-day period, accounting for 48% of total air traffic and roughly 10 million passengers.

Background

The London Volcanic Ash Advisory Centre (VAAC) was responsible for providing information about the ash plume to the relevant civil aviation authorities in the form of Volcanic Ash Advisories (VAA). On the basis of this, the authorities made decisions about when and where airspace should be closed due to the safety issues. Their decisions resulted in the cancellations of flights at airports across the world, not only in those countries where airspace was restricted. On 16 April 2010, 16,000 of Europe's usual 28,000 daily scheduled passenger flights were cancelled and on the following day 16,000 of the usual 22,000 flights were cancelled. By 21 April 95,000 flights had been cancelled.

Before this, the most severe restrictions to air travel in recent times were following the attacks of 11 September 2001 in the United States when all civil air traffic (not just scheduled) in US airspace, and to and from the United States, was grounded for three days.

Professor Bill McGuire of the Aon Benfield UCL Hazard Research Centre said on 15 April that the most notable eruption of the Icelandic volcano Laki which occurred in 1783, would, if it occurred today "have the potential to severely affect air travel at high northern latitudes for six months or more". The last time the Eyjafjallajökull volcano erupted, in 1821, it spewed ash for over a year. Geophysicists in Iceland said that the production of ash from Eyjafjallajökull was likely to continue at a comparable level for some days or even weeks; a geophysicist at the Icelandic Meteorological Office said, "Where it disrupts travel depends on the weather. It depends how the wind carries the ash".

Jet engine tolerance to airborne particles

In 1982, British Airways Flight 9 flew through volcanic ash of Mount Galunggung, Java, Indonesia, causing all 4 engines to shut down. However, the crew restarted all but one of the engines and landed safely. Subsequently, there was an addition to the operations manuals, describing how to deal with volcanic ash.

In 1989, KLM flight 867 was on its approach into Anchorage, Alaska when the Boeing 747-400 flew through volcanic ash from Mount Redoubt causing all 4 engines to shut down. The crew were able to restart both engines on the left wing and landed safely in Ted Stevens International Airport.

Iceland's authorities had been warning airlines for several years, asking them to determine the density of ash that is safe for their jet engines. However, prior to the volcanic events of April 2010, aircraft engine manufacturers still had not defined specific particle levels above which engines were considered to be at risk. The general approach taken by airspace regulators was that if the ash concentration rose above zero, then the airspace was considered unsafe and was consequently closed.

The April eruption of Eyjafjallajökull caused enough economic difficulties that aircraft manufacturers were forced to define specific limits on how much ash is considered acceptable for a jet engine to ingest without damage. On 21 April, the CAA in conjunction with engine manufacturers, set new guidelines which allowed aircraft to fly when there are levels of volcanic ash between 200 and 2000 micrograms (2 milligrams) of ash per cubic metre. These levels were declared by governments, aircraft manufacturers, and airlines not to have safety implications if appropriate maintenance and ash inspection procedures were followed.

From noon 18 May, the CAA further revised the safe limit upwards to 4 milligrams per cubic metre of air space. Any airspace in which the ash density exceeds this limit is categorised as prohibited airspace.

To minimise the level of further disruption that this and other volcanic eruptions could cause, the CAA announced the creation of a new category of restricted airspace called a Time Limited Zone (TLZ). Airspace categorised as TLZ is similar to airspace experiencing severe weather in that the restrictions are expected to be of a short duration; however, the key difference with TLZ airspace is that airlines must produce certificates of compliance in order for their aircraft to enter these areas. Flybe was the first airline to conform to these regulations and their aircraft will be permitted to enter airspace in which the ash density is between 2 mg and 4 mg per cubic metre.

Airspace restrictions in Europe

Under international regulations, all scheduled passenger flights operate under the instrument flight rules (IFR) which requires clearance to be obtained from air traffic control. From 14 April onwards, the controlled airspace was closed in several European countries and no IFR clearances were granted. The airspace of Iceland itself was hardly disrupted in this period (although a change in the wind direction on 23 April caused the main airport to be closed).

By 23 April, the restrictions were lifted over much of Europe through the introduction of new guidelines on volcanic ash density. After this date there were sporadic closures from time to time, notably in the UK, Ireland, and Iceland, but not a blanket shutdown.

Disruptions outside Europe: Canada

Almost every country with an international airport experienced some disruption due to flights to or from Europe being cancelled. Canada was the only country outside Europe recorded as having cancelled any flights due to a risk from ash clouds in its own airspace.

The Canadian airspace was never closed or restricted because of volcanic ash. Although the UK Met Office map of 21 April shows the ash cloud reaching Labrador, Newfoundland, the Maritime provinces, far eastern Quebec, and the Gulf of St. Lawrence, concentrations were expected to be sparse."Canada Sees 'Low Risk' From Volcanic Ash Drifting West"
''The Wall Street Journal'', 20 April 2010

On Monday, 19 April, the combination of heavy fog with a warning by Transport Canada and Nav Canada of a 30% risk of volcanic ash reaching St. John's led to the cancellation of several flights scheduled to leave St. John's International Airport, Gander, and Deer Lake. Because of the heavy fog, it is unclear if the ash cloud warning was really the cause of the cancellations and delays in Newfoundland, and most flights returned to their normal schedule within the day. Air Canada said their flights were "subject to some delays due to inclement weather, unrelated to ash cloud." On Tuesday, 20 April, two Air Canada Jazz flights between the Magdalen Islands and Quebec City cancelled stop-offs in Gaspé because of ash over the Michel-Pouliot Gaspé Airport.

Attempts to reopen airspace

Most airspace started to close from 15 April. However, in the days following there were brief windows free of the cloud at different locations which were exploited to make a few aircraft movements. There then followed test flights and pressure grew to re-evaluate the criteria for safe levels of ash to fly through.

On 16 April a 30-minute break at Manchester allowed two flights to land, and one aircraft to be moved to Florida, empty (as there was no time for passengers to board). At Glasgow, an Air Transat flight to Toronto took off while a British Airways flight from New York, and a Thomas Cook flight from Orlando and Icelandair flights from Keflavik landed.

On 17 April 2010, the president of German airline Air Berlin, in an interview with the newspaper Bild am Sonntag, stated that the risks for flights due to this volcanic haze were nonexistent, because the assessment was based only on a computer simulation produced by the VAAC. He went on to claim that the Luftfahrt-Bundesamt

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