Knowledge-based systems (KBS) are advanced systems for representing complex problems. Their architecture and representation formalisms are the groundwork of today’s systems. The knowledge is usually derived from expertise in specific areas and has to be validated according to a different methodology than is used in conventional systems because the knowledge is symbolic. This paper describes the design, definition and evaluation of a knowledge-based system using the CommonKADS (CKADS) methodology to formally represent contextual information for the Appear platform. We also evaluate the context-aware information system from the user’s point of view using a U2E system and also validate it through a simulated example in a realistic environment: an airport domain, which is a significant step towards formally building KBS applications.