ON AN ABSOLUTE SAFETY CRITERION FOR THE PROBABILITY OF THE COLLISION BETWEEN AIRCRAFT

摘要

The safety of separation of aircraft can be assessed by calculating the probability of collision is the worst possible case, which for certain scenarios can be related to the probability of coincidence, as an alternative safety metric. Examples of safety metrics in the case of two aircraft flying always at minimum separation distance, are: (ⅰ) the maximum probability of coincidence P_0, at the one point; (ⅱ) the one-dimensional cumulative probability of coincidence P_1 along the line joining the two aircraft; (ⅲ) the three-dimensional probability of coincidence P_3 over all space; (ⅳ) a two dimensional probability of coincidence P_2. The latter two are defined in the present paper. It is shown that the general formula for P_n which holds for n = 0,1,3 also holds for n=2. The ICAO Target Level of Safety of probability of collision is comparable to P_1. Since P_2 has no dimensions, it can lead to an absolute safety standard, which is independent of time or distance flown. A value of this absolute safety standard is proposed, which is consistent with the ICAO TLS standard for the usual flight separation rules.