New Delhi, June 21 -- Last December, the UK's second-largest airport Gatwick lay shut for several days as drones, or unmanned aerial vehicles, were found hovering around the airfield, raising a security alarm. The disruption was so severe that the authorities had to call in the army. It is situations like this that India needs to prepare for, as private drones take to the skies. The country's aviation regulator, the Directorate General of Civil Aviation has permitted two Bengaluru-based companies to make and sell these remote-controlled flying devices....