volcanic ash near active volcanoes can damage propellers, engines and cockpit windows. In 1982, British Airways Flight 9 flew through an ash cloud and temporarily lost power from all four engines.Prior to 2010 the general approach taken by airspace regulators was that if the ash concentration rose above zero, then the airspace was considered unsafe and was consequently closed.[21] Volcanic Ash Advisory Centers enable liaison between meteorologists, volcanologists, and the aviation industry