Using a Causal model for Air Transport Safety ( CATS ) for the evaluation of alternatives

The development of the Netherlands international airport Schiphol has been the subject of fierce political debate for several decades. One of the considerations has been the safety of the population living around the airport, the density of which has been and still is growing. In the debate about the acceptability of the risks associated with the air traffic above The Netherlands extensive use has been made of statistical models relating the movement of airplanes to the risks on the ground. Although these models are adequate for the debate and for physical planning around the airport, the need has arisen to gain a more thorough understanding of the accident genesis in air traffic, with the ultimate aim of improving the safety situation in air traffic in general and around Schiphol in particular. To this aim a research effort is underway to develop causal models for air traffic risks in the expectation that these will ultimately give the insight needed. In earlier papers we described the model, the underlying concepts and the mathematical principles used in building the model. In this paper the complete model is briefly described and a few examples are given of the use of this model in comparing the risk of alternative solutions for airtraffic problems in and over the Netherlands.