A tug boat removes fuel from USS Guardian after grounding itself on Tabbutaha Reef in 2013 when digital charts were incorrect. Image source: NOAA.
Worldwide, countries recognise the need for backup navigational systems to the primary satellite-based GPS. But not all backups are equal. The underlying concern with the world’s overwhelmingly dominant navigation system, GPS, is that the satellites are susceptible to tampering.
With relatively weak signals they require very little power to be jammed or spoofed. While illegal in most places, jammers are available online for purchase and can produce enough interference to disrupt aviation and mobile phone signals. South Korea has been the victim of countless GPS jamming attempts by their neighbour to the north, but these satellites can also fail simply due to solar weather.
One solution taken up wholeheartedly by South Korea is a land-based system based on WWII technology called LORAN. LORAN stands for LOng RAnge Navigation system, and its modern manifestation, Enhanced LORAN (eLORAN), provides accurate 2D positioning, navigation, and timing (PNT) services. The system comprises a network of high-powered antennae and powerful transmitters – more than 1 million times the power of GPS.
eLORAN meets the accuracy, availability, integrity and continuity performance requirements for maritime harbor entrance and approach maneuvers, aviation non-precision instrument approaches, land-mobile vehicle navigation and location-based services. The downside to eLORAN is the fact that the network is yet to be built in places like the US, and only limited extend in the north eastern Atlantic.
SO while the International Maritime Organisation recommends the use of at least two independent dissimilar PNT sources to make it robust and fail safe, the UK, Ireland and Europe have abandoned their eLORAN plans and have reverted back to an exclusively satellite-based backup navigation strategy with the Galileo satellite constellation and the Global Navigation Satellite System (GNSS). While the GNSS offers redundancy in the form of several satellite networks, it does not fit the directive of the IMO to adopt an independent and dissimilar source of PNT.
To read about the ongoing GNSS enhancements, see this week’s related article on Galileo’s ground control milestone here.
Norway’s Ministry of Transport and Communication said eLoran was “outdated and had very few users”, adding that lighthouses, markers, and radar beacons provided sufficient navigation safety in waters near the shore.
However, to expect that human judgement is a sound navigational backup system may be naïve in the wake of USS Guardian grounding on a World Heritage site coral reef near the Philippines. While relying exclusively on out-of-date digital charts, the navigation team failed to see the misplaced reef and ran the minesweeper so far aground that the ship had to be dismantled to avoid further reef damage.
Presently, South Korea and Russia are still pushing ahead with eLORAN and the US is currently considering their own program of backup navigation using the land-based system. Until the UK, Ireland and Europe dismantle their eLORAN network entirely, there is the possibility that future uptake of the system by counties like the US will provide the necessary participation to reopen transmitters in the eastern Atlantic.
