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Commercial airplanes generally travel airways similar to roads, although they are not physical structures.
Airways have fixed widths and defined altitudes, which separate traffic moving in opposite directions.
Vertical separation of aircraft allows some flights to pass over airports while other processes occur below.
Air travel usually covers long distances, with short periods of intense pilot activity at takeoff and landing and long periods of lower pilot activity while in the air, the portion of the flight known as the “long haul.”
During the long-haul portion of a flight, pilots spend more time assessing aircraft status than searching out nearby planes.
This is because collisions between aircraft usually occur in the surrounding area of airports, while crashes due to aircraft malfunction tend to occur during long-haul flight.