WAYPOINT - How far can you trust your data?
Dr Andy Norris, an active Fellow of The Nautical Institute and the Royal Institute of Navigation, looks at four key concepts of data integrity and its undoubted role in successful passage planning.
Passage planning is a necessary and demanding task, but it is obvious that a good plan both simplifies and lessens the risks of the associated watch-keeping duties. However, passage planning must take into account the reliability of all the data used for the task. In ‘IT-speak’ we tend to call this data integrity; a concept which is equally important when watch-keeping decisions are being made.
Intelligence from such sources as charts, sailing directions, maritime safety information, meteorological data and lists of radio signals all require just as much data integrity wariness by the user as the data coming from equipment such as the Global Navigation Satellite System (GNSS), radars, and gyros.
In short, data integrity incorporates four concepts: validity, plausibility, comparison and latency. These concepts are examined in fuller detail in the box on the right
eNavigation gives the possibility of all data being used for marine navigation to be electronically marked with integrity information, whatever the data source. This would ease both human instigated and automatic checks to help ensure its appropriate use. For instance, it could include such items as accuracy limitations, original source of data and time/date validity information. For any data it should be easy to select the option to view such information. Automatic indications could be given if user preset limits concerning data integrity were encountered. As a simple example, the user could perhaps set a visible indication on the chart display if the hydrographic survey of an area was particularly old.
To sum up, my advice would be to always treat data with appropriate caution, not least when passage planning. Apply the concepts of validity, plausibility, comparison and latency to help ensure that any risks are minimised.
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