Timing tasks-a concept to reduce operator's workload in complex missions

Distribution of tasks among different operational phases of complex human-machine systems is proposed as a means to balance operator's workload over the operation cycle. The objective of this approach is to enable novice users to bring forward the execution of predictable tasks. This approach is motivated by the observation that expert user can indeed anticipate a situation so as to bring forward tasks. An analysis of tasks in complex environments such as power plants and flight decks is presented and prerequisites for the approach of task timing are identified. Expert systems are described as one possible way of providing novice users with the experienced user's knowledge required for executing tasks in advance. As an application example, task analysis of the approach phase of flights in commercial aviation is outlined. An expert system is introduced that supports route planning tasks in an earlier flight phase in which more mental resources are available than in the high-work-load approach phase.