When atmospheric volcanic ash from an eruption in Iceland drifted over Europe in April 2010, Europe’s aviation system was caught like a rabbit in the headlamps.

Extensive ash in European airspace was a first in modern aviation history. But when volcanic ash drifts into the continent’s airspace again, the European Aviation Safety Agency has no intention of being unprepared.

The agency has issued a special information bulletin to all operators reminding them of the systems and procedures devised since the 2010 ash event, with the intention of avoiding the paralysis that afflicted almost all flying in European airspace for an entire week.

Today, atmospheric ash clouds can be better tracked and identified, and the risks to aircraft associated with ash of varying concentrations are better understood by both authorities and airlines.

Also, a special unit – the European Aviation Crisis Co-ordination Cell (EACCC) – was set up following the 2010 event.

The unit maintains an integrated system for communicating ash data and advisories to air navigation service providers (ANSPs) and operators. Once the data and risk assessment has been supplied to the airlines, the fly/no-fly decision rests with them, not with the authorities.

The EACCC carries out regular exercises annually. The last was in April.

These measures should all help overcome the major factors in 2010’s systemic paralysis – a result of ANSPs reacting nationally, while the ash cloud was hardly going to respect borders.

Now, however, not only are ANSPs and aviation authorities linked to the EACCC, but they all have access to real-time ash cloud information and decision guidance. This is offered via Eurocontrol’s network-operations portal, which includes a web tool dubbed EVITA – European crisis visualisation interactive tool for air traffic flow control.

ANSPs can use all these tools to best plan use of their airspace as a part of the whole European system.

The EACCC is critical to the success of the whole operation, and gets its authority and control from Eurocontrol’s Network Manager, under EU rules adopted following the 2010 incident.

The Network Manager is a new version of the operation that used to be known as the Central Flow Management unit.

EASA is also a permanent member of the EACCC team. As a result, the EACCC has the direct authority of the EU, which is important when it demands co-operation from national ANSPs and aviation authorities.

In April 2010 – in the absence of leadership from EASA and Eurocontrol, which simply had not foreseen such an event – the member states’ aviation agencies reverted to looking after their own backyards, and there was a total lack of network co-operation.

Since then, EASA has also developed detailed advice about operations in atmospheric volcanic ash which was absent in 2010.

The simple answer is to avoid visible ash, and to be guided by an ash-risk zoning system to be published by volcanic ash advisory centres in London and Toulouse.

EASA advises operators to avoid operations in visible volcanic ash or – in cloud or at night – avoid operations where ash is forecast to be present.

The agency also says the forecasted presence of volcanic ash should be presented graphically in the form of a zoning system depicting areas of low, medium and high concentrations in three altitude bands.

The EACCC will do this using information from the advisory centres.

States are also asked not to close their airspace just because ash is forecast to be present in it – although they may close airspace close to an active volcano. Airlines are deemed fully responsible for what they do with the information provided. It is advisory, not compulsory – but if they ignore it and things go wrong, they will not be well placed.

EASA recommends that an operator should only enter areas with medium or high forecast ash contamination if they have “established a volcanic ash safety risk assessment [VA SRA] for such operations”.

This means airlines must obtain damage resistance information from the airframe and engine manufacturer – which may be reluctant to provide it. In addition, for European operators, “a VA SRA should be developed and agreed with the respective [national aviation authority], in accordance with the guidance provided”.

Non-European operators, EASA says, “should establish their VA SRA in accordance with ICAO Document 9974, Risk management of flight operations with known or forecast volcanic ash contamination”. EASA says it will compile a list of operators “known to have developed an acceptable VA SRA” in association with their national aviation authority.

Keeping the 2010 event in mind, EASA adds: “Airspace closure should be an action of last resort, contemplated only in situations in which the VA SRA approach can no longer be relied upon to secure safe operations.”

Operators will naturally want to know the reliability of the ash distribution forecasts from volcanic ash advisory centres, which are based on computer models of known eruption output and the winds that distribute the ash at various levels.

Measurements can be taken by aircraft equipped with special sensors to validate the models. These are often piston-powered aircraft, which have a much lower vulnerability to ash damage than turbine engines.

Meanwhile, horizontal ash drift can also be tracked by satellite under certain conditions.

Since the Eyjafjallajokull eruption in 2010, the UK has equipped a special aircraft to back up the Dornier 228 it previously used for atmospheric measurements.

This aircraft – the Met Office civil contingencies aircraft – is a Cessna 421C. A high-performance piston twin, the aircraft bristles with external sensors and internal computing power.

Several European countries also have research aircraft similarly equipped, and these will be capable of gathering data about the nature and behaviour of the ash clouds – both for tactical operational use and to extend scientific knowledge of the phenomenon.

The ash distribution models published by volcanic ash advisory centres following the Eyjafjallajokull eruption were found to be remarkably accurate in lateral distribution, but the height of ash cloud layers was more difficult to predict.

However, if clouds can be “seen” – as a pilot can see storm clouds on weather radar – aircraft could fly not only around them, but also above or below them.

Even before 2010, Fred Prata of the Norwegian Institute of Air Research was working on systems for tracking and detecting atmospheric volcanic ash.

Since then, working with EasyJet and Airbus, this research has resulted in a system dubbed AVOID – airborne volcanic object identification and detection.

Basically a smart infrared detector, an AVOID prototype has been validated in airborne trials with real volcanic ash, and a company called Nicarnica Aviation has been set up to market it.

Nicarnica has linked up with Israeli manufacturer Elbit Systems to put AVOID into production, and EasyJet hopes to be able to fit it to some of its fleet next year.

EasyJet says that in the early models, its pilots will see the ash picture on the displays of their Class 2 tablet electronic flightbags. Airbus says it would ultimately like to be able to integrate the visual information into its main avionics display.

The need for systems like AVOID is beginning to look increasingly urgent.

Source: Cirium Dashboard