Airport projects can have a significant impact on sustainable development. In Germany, as in many other developed countries, airport development is confronting a dilemma because, on the one hand, airports are important infrastructural components and, on the other hand, airport development faces strong resistance from local populations and interest groups. Thus, uncertainties and long time periods, up to 20 years from the beginning of planning to breaking ground, are quite normal. To ease airport development in Germany, administrative procedures and public participation were enhanced. Nevertheless, even with improved public participation, siting decisions in the case of Berlin Brandenburg Airport (BER) were lengthy as usual and remain controversial today due to the selection of Schönefeld as the site. Against this background, it seems that public participation in the case of the BER site selection did not particularly deliver the hoped-for results, but why? To answer this question, Creighton’s principles of effective public participation are employed as benchmarks. Moreover, the benchmarking indicates that public participation was not effectively applied. Thus, the possible benefits of public participation could not or could only be partly reaped. Furthermore, from a broader politico-economic perspective, the analysis exposes that public participation was just “a small cog in the machine” of the BER site selection process. It seems that other factors had a more substantial influence on the siting decision than public participation and led decision makers, in addition to regular challenges, into a predicament that might have made Schönefeld the only possible siting solution. In this context, different counterfactual scenarios are discussed to show under which circumstances other outcomes might have occurred regarding the BER site selection.