About the volcanic eruption in Iceland that has brought a halt to air traffic over the North Atlantic and much of Europe, this morning's ten-minute set of links and tips.
- Is this a known issue in aviation weather, aviation safety, and so on?
Yes, indeed. Among the list of weather-condition abbreviations that pilots are supposed to know in order to read METARs (don't ask, a readout of local weather conditions) , is "VA," for Volcanic Ash. A description of the oddity of METAR abbreviations is here, including why "BR" means Mist (Americans are taught to remember, "Baby Rain," but that's not the reason) and "GR" means Hail.
For the basic USGS background on the problem, see here and here; for a conference on the topic, here.
- Why does it matter in theory?
The reasons laid out in newspaper stories worldwide in the past 24 hours are actually true! The volcanic ash particles are extremely fine bits of pumice with tremendous abrasive potential. Even in concentrations too low to be visible as a big threatening "plume," they can in theory cause big problems for: the turbine power plants (aka jet engines) of modern airplanes, operating at tremendous speeds and pressures with very fine tolerances among all the moving parts; the leading edges of the wings, whose precise contours affect the flow of air over the wing and therefore the plane's ability to fly; pitot tubes (for gauging air speed) and other external devices; the plane's paint job; and windows in the cockpit, conceivably making it impossible for the pilots to see.