A theory of safe separation standards for air traffic control

Expressions for collision risk are given in terms of elementary probabilities and of frequencies with which aircraft pass each other in the three dimensions of space. Techniques are proposed for setting confidence limits to estimates of the probabilities, including those that depend on the occurrence of large, rare flying errors, so that similar confidence may be placed in estimates of collision risk. The large errors are represented by three alternative mathematical deseriptions, so that the decisionmaker, when considering proposals for separation standards, can compare the effect of alternative key assumptions on the estimated risk of collision.