IMechE director calls for more testing of ash cloud dispersal

The IMechE’s director of engineering has called for test flights to be carried out to verify the theoretical modelling of ash cloud dispersal in the wake of the Grimsvötn volcano eruption.

Grimsvötn, Iceland’s most active volcano, began erupting on 21 May with the resulting ash plume causing flight disruption over Iceland, Scotland and northern Germany.

‘More test flights should be taking place,’ said Dr Colin Brown, IMechE’s director of engineering. ‘It’s only by flying up to these areas, measuring the amount of ash in the atmosphere and the way it accumulates in engines that work can be done to prevent disruption to air travel due to volcanic ash in the future.’

Ryanair has conducted its own flight verification but did so as it doubted the location of ash concentrations.

Following a direction from the Irish Aviation Authority, Ryanair cancelled all flights to and from Scottish airports yesterday, and today issued a statement stating it has grounded flights to and from Bremen, Lubeck, Magdeburg and Berlin in Germany.

The airline, which incurred pre-tax costs of €29.7m (£25.9m) as a result of the Eyjafjallajökull volcano eruption in 2010, described today’s airspace closures over Germany as ‘unnecessary’ and maintains that there was no basis for yesterday’s flight cancellations.

The airline queried whether ‘red zones’ — areas containing high concentrations of ash — existed in Scottish airspace, describing them as ‘mythical’ and ‘another misguided invention by the UK Met Office and the [UK Civil Aviation Authority] CAA’.

Ryanair said it conducted a one-hour verification flight up to 41,000ft in Scottish airspace yesterday and concluded that during the flight there was no visible volcanic ash cloud or any other presence of volcanic ash. The post-flight inspection is said to have revealed no evidence of volcanic ash on the airframe, wings or engines.

The UK Met Office, however, reported yesterday that satellite and Lidar observations confirmed the presence of ash over northern Britain and gave four examples of aircraft encountering volcanic ash. Click here to read more.

Minimising disruption

The UK CAA said on 23 May that the impact of volcanic ash on aviation would depend on weather patterns and the nature and density of ash present in the airspace.

It added that lessons learnt from last year’s eruption at the Eyjafjallajökull volcano should help minimise disruption to air travel.

Since last year, arrangements have been made to mitigate the effects of volcanic ash events.

Areas of high-, medium- and low-density ash will be identified using information provided by the Met Office’s Volcanic Ash Advisory Centre. This is based on data provided from the source of the volcano, satellite and weather balloons, plus ground-based instruments.

Information on the high- and medium-density zones is communicated to the aviation industry and any airline wanting to fly in areas of medium- or high-density ash is required to have a safety case accepted by the CAA.

Andrew Haines, chief executive of the CAA, said: ‘We can’t rule out disruption, but the new arrangements that have been put in place since last year’s ash cloud mean the aviation sector is better prepared and will help to reduce any disruption in the event that volcanic ash affects UK airspace.’

The three levels of ash density are defined as:

Area of low contamination: an airspace of defined dimensions where volcanic ash may be encountered at concentrations equal to or less than 2×10-3 g/m3, but greater than 2×10-4 g/m3.

Area of medium contamination: an airspace of defined dimensions where volcanic ash may be encountered at concentrations greater than 2×10-3 g/m3, but less than 4×10-3 g/m3.

Area of high contamination: an airspace of defined dimensions where volcanic ash may be encountered at concentrations equal to or greater than 4×10-3 g/m3, or areas of contaminated airspace where no ash concentration guidance is available.