Human reliability and the impact of control function allocation in the design of dynamic positioning systems

The design and function allocation of control in complex technological systems have mainly been technology-driven, resulting in increased automation. A human or user perspective is rarely taken in the technological development. The pertaining attitude seems to be that increased automation will reduce the occurrence of human error and thereby ensure safer design and operation. Increased levels of automation, however, may come with a cost of reduced situation awareness for the human operator. This is also the case in the design of the dynamic positioning (DP) system for vessels. Accident statistics show that the frequency of collisions in certain DP operations is above the acceptance criteria and that a combination of technical and human failures were the main causes in nearly all accidents. This article underlines the importance of considering the role of the human operator and human reliability in the design and operation of DP systems. It presents a functional model of the DP system, and discusses current function allocation of control and its impact on operators’ situation awareness and performance. This article concludes with recommendations regarding function allocation of control and visualization of operational risk to enhance operator performance and reliability.