Context
Air routes are practically unlimited:
North Atlantic.
Inside North America and Europe.
Over the North Pacific.
Inside Asia.
Multidimensional constraints:
Site (a commercial plane needs about 3,300 meters of track for landing and take off).
Climate, fog and aerial currents.
Air activities are linked to the tertiary and quaternary sectors:
Finance and tourism that require movements of people.
Accommodating growing quantities of high value freight.