Huge eyeballs painted on jet engines have reduced mid-air collisions with birds by 20 percent over the past three years, Japan's All Nippon Airways (NA), said. It was not known why the trick worked, but an airline spokesman said the eyes seemed to trigger an instinct in the birds that made them veer away from the approaching aircraft. The airline has received requests for information about the black-and-white eyeballs from a number of firms, including Air France, Boeing and Lockheed.