US AVIATION REGULATIONS INCREASE PROBABILITY OF MIDAIR COLLISIONS

A purely stochastic Monte Carlo model is used to compare the relative midair collision course probabilities and mean closing velocities of f our systems of rules for aircraft cruising altitudes as a function of altitude error: (1) current U.S. federal rules, (2) random altitudes, and (3) two proposed alternatives to the current rules. This model inc rements error while: (1) counting collisions among cruising pairs of a ircraft following the four rules being tested on random headings betwe en randomly placed airports, and (2) calculating mean closing velociti es for each rule. The calculations verify that: (1) federal rules incr ease collision course probabilities by about four times more than for a chaotic system of aircraft cruising at randomly selected altitudes, (2) risk is directly proportional to the level of compliance, and (3) mean closing velocities resulting from the current rule are slightly l ess than for random altitudes, while being almost twice as high as for the proposed rules. High closing velocities are shown to increase the collision probability.