| In April, ash from Icelandic volcano Eyjafjallajokull | | | | function of propeller or jet aircraft. It is so fine |
| (pronounced AY-yah-fyah-lah-YOH-kuul) grounded | | | | that it will invade the spaces between rotating |
| flights across the globe heading to and from | | | | machinery and jam it. The silica melts and fuses |
| Europe for days. Although no aircraft were | | | | on to the turbine blades and nozzle guide vanes |
| actually affected, airline companies kept their | | | | (another part of the turbine assembly), which in |
| planes grounded, based upon government safety | | | | modern aircraft operate at a much higher |
| policy. The effects of this cost the airlines billions | | | | temperature than that needed for the silica to |
| of dollars, and after being grounded for days, | | | | melt. Aircraft avionics and electronics can also be |
| they complained that the government agencies | | | | damaged. Flying through the ash cloud presents |
| making the decisions overreacted to the problem. | | | | the danger of engine failure, among other |
| Volcanic ash is formed during explosive volcanic | | | | potential problems. |
| eruptions, which create particles consisting of small | | | | Considering that most airlines are already losing |
| tephra, or bits of pulverized rock and glass. This | | | | significant amounts of money and we are still not |
| can be a major hazard to aircraft because it is | | | | yet out of the woods from the global financial |
| invisible to aircraft weather radar and is often not | | | | crisis, it is no surprise that they protested having |
| immediately noticed by pilots. Volcanic ash is hard, | | | | to have tens of thousands of flights grounded for |
| does not dissolve in water, is extremely abrasive | | | | days. While it is certainly open for debate whether |
| and mildly corrosive, and conducts electricity when | | | | the governments involved in Iceland's ash |
| wet. | | | | problems overreacted when confronted with |
| Aircraft avoid any airspace that has volcanic ash | | | | having to decide the best course of action, there |
| in it because the ash can interfere with the | | | | are sound reasons for the concern. |