Collaboration is the key to integrating unmanned aircraft into the airspace, keynote speakers from three countries said at the opening of the Second Global Remotely Piloted Aircraft Systems Symposium, held at the Montreal headquarters of ICAO, the International Civil Aviation Organization.   Alessandro Cardi, deputy director general of Italy’s ENAC aviation authority, said his country began its regulatory work with mid-size UAS, such as the Piaggio P1HH Hammerhead, unveiled a few years ago at the Paris Air Show.   For that aircraft, and others of a similar size such as the Falco UAS, Italy is using segregated airspace for such operations as humanitarian missions and commercial cargo delivery demonstrations.