TRADEOFF OF COLLISION RISKS IN AN AIR ROUTE SYSTEM USING SYSTEMATIC OFFSETS FOR GPS EQUIPPED AIRCRAFT

摘要

The advent of GPS equipped aircraft with high navigational accuracy is increasing the vertical collision risk for aircraft flying the adjacent flight levels on the same route. To avoid the increase in the risk, the systematic lateral offset has been proposed. It significantly decreases the vertical collision risk of aircraft pairs assigned on the adjacent flight levels. On the other hand, it might increase the lateral collision risk of the aircraft assigned on the adjacent routes. This paper analytically investigates adverse effects of the offset on the lateral collision risk. The risk ratio, which is defined by the ratio of collision risk for the system with offsets to that for the system without offsets, is investigated to look at the effects relatively. Then, the absolute collision risk values are calculated using the recent parameters for the NOPAC route. The results indicate that the increase of lateral collision risk due to the lateral offset of 2NM is less than 7% compared with the system without offsets, although the vertical collision risk is significantly reduced in the case.