Understanding of navigational information systems

Navigational information systems became one of the main devices on ship’s bridge supporting navigators in evaluation of navigational situation and undertaking decisions. For instance ECIDS supports navigation by gathering information and automating some process like plotting of position of own ship and other objects on the scene. Any navigational information system has got advantages and limitations. Their understanding should help navigators to perform watches in a safer way. This article presents a discussion on some deficiencies of navigational information systems. Discussion is underlined by three accidents, which show when misunderstanding or overreliance may lead to catastrophic consequences.