Situation awareness is the perception of environmental elements with respect to time or space, the comprehension of their meaning, and the projection of their status after some variable has changed. It is a field of study concerned with perception of the environment - critical to decision-makers in complex, dynamic areas ranging from aviation, air traffic control, ship navigation, industrial plant operations, military command and control, etc. Having complete, accurate and up-to-the-minute situation awareness is essential where technological and situational complexity on the human decision-maker are a concern.

• Provides guidance to design, build, operate, and maintain effective HMIs which result in safer, more effective and efficient control of the process, in both normal and abnormal situations
• Improves user abilities to detect, diagnose, and properly respond to abnormal situations
• Enables users to be more effective in achieving:
• Improved safety
• Quality
• Production
• Reliability
• Is applicable to continuous, batch, and discrete processes – in fact any process using an HMI for interfacing to a controlled system

• Graphics are easy to read and intuitively understandable
• Graphics show the process state and conditions clearly
• Graphic elements used to manipulate the process are clearly distinguishable and consistently implemented
• Graphics do not contain unnecessary details and clutter
• Graphics convey relevant information, not just data
• Information has prominence based upon its relative importance
• Alarms and indications of abnormal situations are clear, prominent, and readily distinguishable

• Graphics functions are standardised, intuitive, straightforward, and involve minimum keystrokes or pointer manipulations
• The HMI is set up for navigation in a logical, hierarchical and performance-orientated manner

• Graphic elements and objects (wizards/controls) behave and function consistently in all graphics and all situations
• Important actions with significant consequences have confirmation mechanisms to avoid inadvertent activation
• Design principles are used to minimize user fatigue, since operators use the HMI constantly

• Grey backgrounds are used to minimize glare, along with generally low-contrast graphic elements. The best RGB colours for backgrounds are:
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• Process lines and outlines of vessels and equipment are dark grey or black. Emphasis is provided by differences in line thickness, not colour
• No gratuitous animation, such as spinning agitators or pumps, moving conveyors, splashing liquids or sprayers. Animation is only used to highlight abnormal situations
• Depiction of process values is done in the context of information presented and not just simple numbers on a screen
• Important information and key performance indicators have small, in loco trends
• Colour is used only to indicate alarm conditions
• Equipment is depicted in simple 2-D low contrast, not brightly coloured 3-D with shadowing, etc.
• Layout is consistent with the accepted mental model of the process which is often not the same as the P&ID layout
• Navigation methods are logical and consistent
• Graphics are hierarchically structured, supporting progressive exposure of detailed information
• Access to displays requires the minimum number of keystrokes or clicks
• Techniques are used that minimize the possibility of operator mistakes
• Validation and security measures are implemented
• Graphics are layed out such that wherever possible process flows from left to right. Gases flow upwards and liquids flow downwards
• Measurement units are shown in low contrast lettering if shown at all

• Priority 4 – Highest: Red
• Priority 3 – High: Yellow
• Priority 2 – Normal: Orange
• Priority 1 – Low: Magenta
• Priority 0 – Lowest: Blue

With regard to audible alarm annunciation, where used, each one of the different alarm priorities should have its own unique alarm sound. For example – Priority 4 Highest – railway crossing bell. The sounds chosen must not be used by any other process or interface in the control room.

An example of this can be seen in theObject Modelling Quick Start Guide, where we create various alarm indications for a hypothetical Pressure Relief Valve.

• The Y-axis span automatically ranges itself to a predetermined scale or predetermined amount relative to the current value, which is rarely the full range of the value being trended
• The time base of the trend is appropriate to process conditions. The slower the scan rate of value trended, the longer the trended period
• Normal bounds, quality limits, or desirable operating ranges are shown on the trend
• Manual alteration of the range and time base are possible and persist to subsequent invocations of the display. A “re-trend” mechanism exists whereby the trend is reset to its default configuration

When precision is not essential, and simple direction, magnitude, and amount of change is sufficient, a small unlabelled trend is placed next to a process value. The shaded area of a spark line trend represents the normal operating range. Clicking on the spark line brings up the normal range and time, e.g. +- 2° C / 1h

There are several methods to display the analog value of a vessel. The goal is to depict the level without undue emphasis or distraction. A trend line is used to display the value: Vessel is shown as 2-dimensional Outline is thin (1-pixel) black line Trend timespan is configurable 3 different sizes are available (small, medium, large) With either 2 or 4 alarm set points Vertical orientation only

The purpose is to represent the operating state of an analog value graphically so as to be assimilated at a glance: 3 different sizes (small, medium, large) 2 different orientations (vertical, horizontal) Normal operating range is pale blue Inner alarm limits are light grey Outer alarm limits are dark grey Current value shown as dark blue index Trending direction show as directional grey arrow

A controller is thought of and depicted as a physical entity. This way, proper information about its operational status can clearly be shown: Process value – expressed in engineering units Set point value – expressed in engineering units Output value – expressed as a percentage Mode – digital value showing Auto or Manual

Minimum of 3 and a maximum of 17 process variables Captures and saves process variable values for future reference Recalls pre-captured patterns and superimposes them under real-time pattern Indicates alarms. When any of the process variables goes into alarm, the shape changes colour based on the highest priority in force. The reading(s) in alarm are highlighted The name of each variable and its value can be seen as a tool-tip when the mouse hovers over the relevant axis

This trend is used to give operators an indication of how they are performing against a set target. It is also dynamic in that it can be reset with new target value after a process change so that operators are then able to see performance relative to the new target.

Different sizes of various standard ISA shapes are provided, once again making use of pattern recognition so that objects can be recognized at a glance. Labelling is not intrusive or of high visibility. In fact, not every item needs a label identification. In particular, tag names are not routinely displayed as they only add unnecessary visual clutter.