The volcanic eruption at the Cordon Caulle complex in Chile during June 2011 ejected volcanic ash some 15,000 metres up into the atmosphere, with the finer ash particles being caught up in the upper level westerly winds.
The massive eruption from Chile's Puyehue volcano produced a massive ash cloud. (Image from Wikipedia Commons - click to enlarge)
Many millions of these tiny particles travelled across the southern Atlantic Ocean, to the south of Africa and then over the southern Indian Ocean and southern parts of Australia and New Zealand.
The ash cloud dispersed over 9000 km at high altitude across parts of the southern hemisphere being detected over New Zealand on Sunday 12th June. (Click to enlarge)
This produced significant disruption to international airline flights across the Southern Hemisphere.
The recent eruptions over Iceland produced similar chaos over the northern hemisphere during April of 2010 when many flights over northern Europe were cancelled.
Volcanic ash clouds tend to stay in the same hemisphere as the volcano of origin, but can stay aloft for several weeks, circumnavigating the Earth at the same time.
Volcanic ash is hazardous to high flying jet aircraft, because particles injected into the engine can produce component failures and flame-outs - or engine stalling. Instrument malfunction can also occur through a clogging process where ash accumulates in sensors such as pitot tubes, producing erroneous readings of air speed.
The first documented case of a modern jet plane encountering a volcanic ash cloud was in 1982, when British Airways Flight 9 flew into ash debris from the active volcano Mount Galunggung, over Indonesia.
Artists impression of Flight BA 9, descending with all four engines stalled and the fuselage glowing with static electricity after flying into a volcanic ash cloud in 1982. (Image form Wikipedia Commons - click to enlarge)All four engines stopped, and a complete disaster was only narrowly averted when a successful restart was made at lower altitude and the aircraft was able to land in Jakarta.
