Is it a plane? Is it a drone? Next time you look up and see vapor trails spreading across the sky, bear in mind that the aircraft you're looking at might just be both. As the aviation industry tightens its belt, its attempts to save money and stay relevant have led to a new rise of "transformers" -- including crop-dusters and business jets given a new lease of life as surveillance aircraft. (edition.cnn.com) 更多...
