Thousands of planes are grounded across Europe due to the spread of volcanic
ash following the recent eruption under Iceland's EyjafjallajÃ¶kull glacier.
Volcanic eruptions eject large amounts of ash and trace gases such as sulphur
dioxide into the atmosphere, often reaching the altitudes of scheduled flights.
When flying through a volcanic ash cloud, ash particles enter the jet engines
which can result in engine failure. The ash can also severely damage the
material of the aircraft, clog its sensors, limit the view of its pilots, and
severely scratch, or 'sandblast', cockpit windows, landing light covers and
parts of the tail and wings.
Over 90 aircraft have sustained damage after flying through volcanic ash clouds.
The total cost of damage sustained by aircraft due to volcanic ash clouds from
1982-2000 is estimated at 250 million US dollars.
Every year there are about 60 volcanic eruptions. Ground-based monitoring is
carried out on only a limited number of volcanoes. In fact, most volcanoes,
especially those which are remotely located, are not monitored on a regular
basis. Therefore, observations of sulphur dioxide (SO2) and aerosols
derived from satellite measurements in near-real time can provide useful
complementary information to assess, on a global level, possible impacts of
volcanic eruptions on air traffic control and public safety.
Ensuring that volcanic cloud hazards are addressed, the Volcanic Ash Advisory
Centres (VAACs) were established in 1995 to gather information regarding
volcanic ash clouds and to assess the possible hazard to aviation. To assist the
VAACS in their tasks, ESA started the Support to Aviation Control Service (SACS)
service to deliver SO2 email alerts to them in near-real time. For
each alert, a dedicated map around the location of the SO2 peak value
that triggered the alert is produced and put on a dedicated web page, mentioned
in the email.
In addition to VAACs, the information â€“ derived from the SCIAMACHY instrument on
ESAâ€™s Envisat, GOME-2 and IASI on MetOp, OMI on EOS-Aura and AIRS on Aqua â€“ is
delivered to volcanological observatories, health care organisations,
To know whether aircraft may safely pass under or over volcanic ash clouds and
to forecast better the future motion of the clouds, the VAACs need more accurate
information on the altitude and vertical size of an ash plume.
This is the main focus of ESAâ€™s Support to Aviation for Volcanic Ash
Avoidance (SAVAA) project which aims to set up a demonstration system able to
ingest satellite data and meteorological wind fields, in order to compute the
injection height profile of volcanic emissions, using trajectory and inverse
modelling. The system can then be implemented into the operational environment
of the VAACs.
Furthermore, the SAVAA project is providing complementary data to the SACS SO2
alerts by developing volcanic ash alert services for VAACs based on satellite
data measured in the infrared part of the spectrum.