"SUPER" OR NOT, VOLCANIC ASH IS A SERIOUS THREAT TO AVIATION
April 8, 2005 — "Supervolcano" - a television movie
airing on the Discovery Channel - explores the global impacts of
an extreme volcanic eruption occurring in Yellowstone National
Park. While actual volcanic events typically occur on a much smaller
scale, airborne ash is no less of a serious threat to aviation.
One mission of the National Oceanic and Atmospheric Administration
is to support safe aviation through the detection and forecast of
More than 100 commercial and military aircraft have encountered
volcanic ash clouds in flight. Consequences of these encounters
include degraded engine performance (including flameout), loss
of visibility and failure of critical navigational and operational
instruments. Encounters have resulted in multiple engine failures,
and disastrous crashes have been only narrowly averted. In addition
to the threat to lives, aircraft damage with its attendant economic
loss can be severe.
While the obvious strategy for an aircraft is to avoid flying
into an ash plume, avoidance requires knowing where an ash plume
exists. Often, ash plumes simply look like normal clouds and many
encounters occur at night.
Pilots, dispatchers and air traffic controllers must be quickly
informed of pre-eruptive volcanic activity, explosive eruptions
and the location and direction of ash plumes anywhere they may
occur around the globe.
On average, 15 major explosive eruptions — those powerful
enough to inject ash above 25,000 feet — occur each year.
Ash plumes from a major eruption can affect aircraft thousands
of miles downwind. For example, when Mt. St. Helens erupted in
1980, the plume reached an altitude of 90,000 feet in 30 minutes
and was 50 miles wide.
NOAA Volcanic Ash Products
NOAA operates two Volcanic Ash Advisory Centers – one in
Anchorage , Alaska and the other in Camp Springs , Md. The centers
issue advisory statements, including graphics and text messages
about the location and size of the ash clouds, which are distributed
through several global networks and posted online in real-time.
NOAA's National Centers for Environmental Prediction, also
in Camp Springs , runs a Volcanic Ash Forecast Transport and Dispersion
model that projects the trajectory and location of the clouds at
different altitudes on certain time scales.
These advisories and dispersion model forecasts are sent to the
Federal Aviation Administration, the U.S. Geological Survey, National
Weather Service Forecast Offices, climate analysts and scientists
throughout the world.
NOAA scientists and researchers use geostationary and polar-orbiting
satellite imagery to track volcanic ash eruptions and ash clouds.
NOAA also operates moored and free-floating data buoys in the world’s
oceans, research ships and aircraft, and land-based environmental
stations – all provide data that is used to track near term
events like a possible eruption or to help combat wildfires, or
for the long-term observation of the planet.
On the Web :
Volcanic Ash Advisory Centers
Washington , DC : http://www.ssd.noaa.gov/VAAC/washington.html
Anchorage , Alaska : http://www.alaska.net/~aawu/vaac.html
Volcanic Ash Transport And Dispersion (HYSPLIT Model): http://www.arl.noaa.gov/ready/ash.html
Carmeyia Gillis, National Centers for Environmental Prediction,
(301) 763-8000 x7163
Chris Vaccaro, NOAA's National Weather Service, (301) 713-0622