A Dolly
A converter dolly that is towed from a single hitch on the centerline of the towing unit.
Negotiated priveleges, between countries, that allows for foreign airlines to fly over, land in or out of another country. These freedoms were initially developed in 1944 and currently consist of nine (9).
Further information, including pictures, can be found at http://people.hofstra.edu/geotrans/eng/ch3en/conc3en/airfreedom.html