The formalization of Air Traffic Control Regulations for the separation of aircraft during approach and departing phases is discussed. Our aim is to demonstrate rules in Positional-Slotted, Object-Applicative (PSOA) RuleML syntax that capture those regulations. This rulebase is combined with aircraft facts, resulting a complete Knowledge Base for the computation of the required separation of aircraft. We provide examples of queries posed in the open-source PSOATransRun system and we show the capabilities and limitations of the Knowledge Base and PSOATransRun.