Monitoring principles in aviation and the importance of operator redundancy

The aim of this paper is to discuss developments in aviation with respect to their affect on redundancy and dependability of the complex human-automation system. With the improvement of technical systems and increasing automation in aviation, the attempts to reduce the number of human operators in the flight guidance system is still one goal of current research. Single pilot cockpit or single controller working positions are the key words for pinpointing this issue. For technical systems, the developments aim at the integration of a higher level of redundancy to improve the dependability. A contrary trend is determinable for the human operator by transitioning to single operator systems. To be able to evaluate this process, this paper analyses three different monitoring principles that form the basis for redundancy and thus dependability. These monitoring principles are (a) the automation-automation, (b) the human-automation, and (c) the human-human. Research that focuses on single operator systems consequently eliminates the human-human monitoring principle. The authors argue that the consequences of this elimination are currently not understood sufficiently and may have a great impact on the dependability of the overall system, as some highly valuable aspects of the human-human monitoring principle would be irreplaceably lost with the transition to single operator systems.