The Airborne Metro is an ambitious travel concept designed to make flying around the world a faster and more efficient process. The benefits are -- Overall carbon fuel economy and in climate impact. Reduction in airport congestion. Reduction in noise at airports.
The Airborne Metro would be powered by nuclear energy so that it would never have to land. The idea behind the concept is to save jet fuel on conventional aircraft by letting them hitch a ride on the metro
This vast concept envisages an era when climate changing emissions, ground congestion and noise pollution will no longer be acceptable at their presently forecast levels. It seeks to sustain the apparently unlimited demands of people for travel without the huge penalties that these are beginning to impose.
The concept depends upon the feasibility of very large flight vehicles, perhaps carrying over 3000 passengers and for these eventually to be nuclear powered. These large "Air Cruisers" would stay aloft on a semi-permanent basis receiving their loads of passengers, freight and supplies in mid-air.
The concept does not require every airport or airline to be compatible with the cruiser concept but most of the large hubs would need to be capable of working in this way.
Reference: innopedia.wikidot and dvice