Design Pattern: PF(2) Spatial dedication and continous visibility


Under all controlled process conditions, even during minor disturbances, the human operator would like to know all key alarms that are directly safety related and important process alarms related to safety critical systems.


The human operator needs to know at all times all key alarms in order to decide which alarms to deal with.


Use spatially dedicated, continuously visible displays to support response to all controlled process conditions. Spatial dedication means that the alarm messages always appear in the same position. Continuously visible means a parallel presentation method is used.

Known uses
Fig1.The most relevant alarms (framed in red) are presented at the top of the Westinghouse alarm presentation system interface
Fig2.The most relevant alarms (framed in red) are presented at the right side of the TotalVision Process Human Machine

A spatially dedicated, continuously visible display has generally been found during high-density alarm conditions to be superior to serial visual displays formats such alarm lists. They ensure both an information rate and a presentation form that will remain manageable under all process conditions. They also allow the human operators a rapid detection and pattern recognition. (Alfieri, V. V. (2001). Task models in interactive software systems. Handbook of Software Engineering and Knowledge Engineering)