AN OVERVIEW OF CASSANDRA‐II

A brief non‐technical overview of the CASSANDRA‐II system is presented. The system performs knowledge‐based monitoring of aircraft movements in controlled airspace, and reports violations of air traffic control rules to the operator. The system is based on the blackboard model of problem solving, but differs in the relative autonomy of its abstraction levels. Abstraction levels, in CASSANDRA‐II, are equipped with control components which are responsible for scheduling all decisions based on the level contents. The system is designed for continuous real‐time operation; in this context, it is important that computer memory does not become full and halt the execution of the system. CASSANDRA‐II contains special‐purpose, knowledge‐based mechanisms for the removal of out‐dated blackboard information.