A generalized model is presented to incorporate objective (hard) and subjective (soft) hazard information in automated decision-aiding systems. The model may be used with more than one hazard, of more than one type, in a given problem. Uncertainties in state measurements, dynamics, hazard extent, and hazard severity are included, as is consideration of the fact that different operators may have different concepts of what is an acceptable or unacceptable risk. By examining the tradeoffs created by these uncertainties, appropriate decision thresholds can be selected. Using an aviation case study, information gained from observation of aircraft behavior in the presence of weather was used to develop a model of weather as a soft hazard. This information could then be used in a decision aid to provide feedback on route acceptability.
IntroductionReal-time decision aiding and alerting systems are often used to assist human operators in controlling processes efficiently and in preventing undesirable incidents from occurring (such as a collision in a vehicle control application, or exceeding temperature limits in process control). There are a number of types of real-time decision aids, ranging from process status displays, to planning tools, to safety-and time-critical warning systems. However, all decision aids can be broadly classified as either active or passive. Active systems generate discrete decisions or commands that are communicated to the operator with the intent of modifying the process' future state trajectory (e.g., a traffic conflict resolution command). Passive systems provide process and environment state information to the operator (e.g., depicting precipitation levels on a weather radar display) without explicit decisions being made by the automation. Thus, an active system acts as an automated decision maker (which may agree or disagree with the human operator's decisions), while a passive system acts as an automated decision supporter.