Since the 2010 volcanic ash crisis, measures have been put in place to ensure that the UK, and the aviation industry worldwide, is prepared for a similar event. The following arrangements now apply in UK airspace, and across much of Europe, in case airspace is affected by volcanic ash.
Areas of ash are identified using information provided by the Met Office's Volcanic Ash Advisory Centre. They supplement this with annotated satellite information showing the likely location(s) of the ash, and forecast ash concentration charts which provide information on the concentrations of volcanic ash you are likely to encounter in that airspace, as described below.
Any UK airline wishing to operate in areas of airspace forecast to be, or aerodromes/operating sites known to be, contaminated with volcanic ask will need to complete an assessment of the safety risks related to known or forecast volcanic ash contamination as part of its management system.
|Airspace contamination level||Ash per m3 of air||Information provided by||Advice|
|Low||Greater than 0.2 but less than or equal to 2.0 milligrams||SIGMET and Volcanic Ash Advisory Centre graphics||
|Medium||Greater than 2.0 but less than 4.0 milligrams||Volcanic ash supplementary products issued by the UK Met Office and Météo-France||
|High||Equal to or greater than 4.0 milligrams||Volcanic ash supplementary products issued by the UK Met Office and Météo-France||
* Non-UK airlines can apply to their own national regulator for similar safety cases.
The new regime maintains high levels of safety while reducing disruption. According to the European air traffic control body Eurocontrol, only 900 of the 90,000 flights due to take place in Europe during the Grimsvotn eruption (23-25 May 2011) were cancelled. Work continues to implement one common regime worldwide and the CAA is directly involved in driving this work in Europe and through the International Civil Aviation Organisation.
Safety cases have been used to set out how they will safely deal with unusual or challenging issues for main years. They set out the measures that airlines will put in place to mitigate risks, in this case of flying through ash. They also include input from aircraft and engine manufacturers, which is important as they can advise on the levels of ash that their engines can safely cope with.
A safety case needs to show that the airline understands the hazard and its own limitations, and that it has in place robust procedures and plans to safely fly in the unusual situation. These procedures may include extra training for crews, additional maintenance inspections, and guidance for pilots as to how they shout react in certain circumstances.
Safety cases are put together by the airlines and presented to their regulator (the CAA for the UK) for acceptance.
The Met Office uses a computer modelling system known as the NAME model to predict where ash will be present and in what density.
The model has been widely endorsed by the international meteorological community and has been tested and proven during previous eruptions and events including Chernobyl and Buncefield.
The Met Office model forecasts the presence of ash, and makes use of a range of information sources including at the source of the volcano, satellite images, test flights, weather balloons and ground based instrumentation.