The now universal use of GPS by vessels of all description has made a significant contribution to the safety and accuracy of marine navigation.

However, continuing news reports of alleged jamming of GPS signals by North Korea, as well as the potential for other sources of signal interference is of widespread concern to governments and to the shipping and aviation industries as a whole.

These reports serve to highlight the risk of vessels being solely reliant on GPS for position fixing and reinforce the importance of utilising all available aids to navigation as required by SOLAS and STCW regulations.

In particular, navigating officers should be encouraged to practice traditional methods of navigation, including celestial observations.

In the Club's latest publication 'Hellas Highlights', David Nichol, UK Club Risk Assessor, highlights some of the common contributory factors identified in casualty reports noting that ''the exclusive use of GPS in coastal or confined waters may not be appropriate and is often a contributory factor in ship groundings''

Mr Nichol advises that in these circumstances ''full use of radar ranges and bearings, visual bearings and transits should also be used as a primary means of fixing the ship’s position. The advantage of cross checking the position using these alternative methods is that it will give the OOW a better situational awareness and sense of orientation of where the ship is located relative to the topography of the coastline and the proximity of hazards. GPS is not infallible. The OOW should be aware of the equipment’s limitations and potential for signal degradation, interference from external sources, as well as the possibility of differences existing between the GPS datum and the datum of the chart in use, causing plotted positions to be discrepant. GPS is an aid to navigation, not a single means of navigation. Furthermore, the value of the “Mark 1 eyeball” should never be underestimated!''

Source: The UK P&I Club