The effect of GPS-based surveillance on aircraft separation standards

The current aircraft separation standards are based in part on the surveillance accuracy of radar measurements. In this study we estimate the effect of GPS-based surveillance on the separation standards. We assume that every aircraft periodically broadcasts its position as derived by an onboard GPS receiver. The position reports are received by ground controllers and are used for aircraft tracking and conflict resolution. Based on the probability distribution functions of GPS and radar measurement errors, we compute the probability of close approach between aircraft and derive the new separation standard that will keep the current safety level. By applying similar arguments, we can estimate the effect of GPS-based surveillance on the minimum runway separation that is required for conducting independent parallel approaches under instrument meteorological conditions. We analyze the various elements of the required runway spacing and study the possible use of velocity estimate in predicting future conflicts. The trade-off between the probability of false alarm and the probability of late alarm and its effect on the required spacing is studied by using a Monte Carlo simulation.