Airport Capacity according to ICAO Rules: Some Quantitative Evaluations

The basis of a planning process is the evaluation of capacity, both in case of exnovo infrastructures and extensions of existing ones. Therefore, the evaluation of capacity is particularly important for an airport so that a correct infrastructure dimension can be obtained. At the beginning of the seventies studies on airport capacity started to be developed due to the increase of air traffic. In fact, as the first wide body together supersonic aircraft came into service in that period air traffic started to rise up significantly. The first scientific and interesting study is probably from R. M. Harris “Models for runway capacity analysis”, report FAA-EM/73-5, McLean, 1974. He developed a model for space distances of couples of aircraft in landing phase on the approach path of a runway. He defined runway capacity in overflow condition on the basis of such distances, pointing out that these conditions happen when at least two aircraft are on the approach path. The most important work probably developed until now concerning airport capacity was the FAA Advisory Circular "Airport Capacity" New York, 1978/1994. The airport capacity for what concern the air side of the airport itself is defined as the less value among runway, taxiway and gate capacity. Several diagrams were showed in the AC. For instance, runway capacity could be obtained under certain input data like the percentage of wide body aircraft, the percentage of arrivals, the touch and go amount etc. Several other works have been developed since then. Many papers concern optimization of arrivals on a runway depending on the interarrival time between an aircraft and the trailing one. As runway capacity depends directly on interarrival times it’s interesting to focus on this. In many works interarrival time is assumed to depend on the weight of the leading and the trailing aircraft. FAA also developed specific rules on this, as known. Nevertheless, interarrival distances applied in the States by Air Traffic Control (ATC) are not valid in the rest of the world. In fact ICAO ATC rules showed in Annex 2 are different from FAA ones. Of course, the applied aircraft distances influence runway capacity directly. The aim of the present paper is to understand until which moment the difference of rules can influence distance times between aircraft and capacity. Several experimental data have been collected on the Naples International Airport, located in southern Italy, during a 30 day period in order to develop the present work. The exact Greenwich Civil Time (GCT) of landing and taking off aircraft have been measured and interarrival and interdeparting times have been subsequently calculated. These measures provided statistic means, standard deviations and percentiles of distance statistic distribution for couples of aircraft. The couple can consist of different weight class aircraft or aircraft belonging to the same weight class. Distance times between two aircraft within 7 minutes have been considered to get a true runway capacity value in the Naples International Airport, both for departing and arriving aircraft. Results obtained in this way have been compared to other authors ones through statistic percentiles and the sampling distributions compared to known ones with a correlation test to understand what can be the influence on runway capacity. Results also show a substancial difference in terms of distance times and this can be reflected on airports subjected to different rules. This matter is very interesting and its further develops are showed in the paper.