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

Under present arrangements, U.S. 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.