Free-flight and en route air safety: A first-order analysis

Under present arrangements, US commercial planes do not travel ‘as the crow flies’ from origin to destination; rather they are generally restricted to paths within a grid. New technologies, however, raise the possibility of moving to a ‘free-flight’ regime under which planes could fly directly from point to point. Striving for general insight rather than definitive conclusions, we use geometrical probability to assess how free-flight could affect the safety and efficiency of en route air traffic operations. We work with two air traffic control sectors: one hypothetical and the other based on actual traffic patterns over Albany, New York. Though tentative, the results suggest that – so long as certain operational constraints are retained – the changed geometry of flight paths after a transition to free-flight might tend in itself to diminish mid-air collision risk. Much depends, however, on whether the human/technological capabilities of future air traffic control can match the extraordinary effectiveness of the existing system.