British authorities scaled back their assessment of the danger volcanic ash poses to jetliners on Tuesday, easing Europe's worst air traffic disruption since World War II but raising the prospect that millions of passengers have been stranded and more than $1 billion in economic activity lost partly because of the overestimated risk.
The British Civil Aviation Authority said new test flights conducted by airlines and reviewed by jet engine makers indicated that commercial airliners could fly safely in low levels of ash -- a position that airline industry officials and some European government authorities have been arguing for days.
Previously, British authorities maintained that virtually any volcanic ash was a threat to aviation. While that position was consistent with international standards, industry officials said civil aviation authorities were being overly cautious. They argued that in recent days ash clouds had cleared enough over Europe for planes to safely navigate around them.
