A JET aircraft may have been almost knocked out of the sky by a previously unknown form of air turbulence, it emerged today. The incident happened over the Rocky Mountains in the US in December 1992. An engine was torn off the DC 8 cargo jet some 10km above the ground.
At first investigators assumed that a "breaking" wave of air - a recognised hazard in mountainous regions - was responsible.
But calculations by Mr Terry Clark, of the National Center for Atmospheric Research in Boulder, Colorado, revealed a previously unknown type of turbulence - a region of highly variable wind speed, shaped like an elongated pancake up to 30km long.
He and his team suspect that this "pancake" is reasonably common and are now trying to work out if it can be predicted, he told New Scientist magazine.