The infrastructure of the global aviation system consists
of two principal elements, airports and air traffic
management (ATM) systems. Airports can be further
subdivided into airside facilities (runways, taxiways,
aprons, aircraft stands) and landside facilities (passenger
and cargo buildings, curbside), while ATM
systems are now viewed as being comprised of a tactical
subsystem—air traffic control (ATC)—and a strategic
one—air traffic flow management (ATFM).