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Home > Crew Matters > Finger on the button: the frailty of the satellite system

Finger on the button: the frailty of the satellite system

We input our unique four numbers, reach for the hand sanitiser as the keypad is cleansed with an antibacterial wipe, wait as the little slip of paper appears through the serrated teeth and rarely think any more about it. Yet the payment we have just made has engaged the functionality of the very same system that was built half a century ago, to provide safety and navigation information at sea.

Originally developed by the US Navy in the 1970s for ship positioning and navigation, the precise timing of the Global Positioning System (GPS) is invaluable to modern electronic commerce. For example, bank transfers and payment card transactions would be greatly hobbled if the system were to shut down, which it does, from time to time.

I smiled as I read this quote from Global Defence Technology where “GPS has been likened to the equivalent of relying on the light from a 25w bulb shining in Sydney to see your way around New York”. Let’s take a moment to consider the interruptions that can wreak havoc with GPS reception, from sunspots and natural events in the ionosphere to civilian and military transmissions, in addition to the often criminal activities of foreign militaries and terrorists.

Consider now the impact on our daily lives should the GPS signals be suddenly disabled. Ships and aircraft, truck and taxi could be ‘lost’; the financial and communication activities, public utilities, security and humanitarian operations and emergency services may well come to a standstill. GPS is everywhere and in everything. As the presidential election of the USA finally concludes, were the subscribers of the Official Trump 2020 App aware that their precise location was being accessed through the GPS?

So, why does a system, that is so deeply integrated into so many aspects of our lives, have such frailty?

As the use of the satellite-based system continues to expand, the implications of potential signal failure become even greater and the continued use of what is, arguably, an old fashioned piece of kit raises the increasingly frequent use of the term ‘single point of failure’ (SPOF).

An SPOF exists when the loss, or malfunction, of just one crucial element within the system, can incapacitate the whole of the rest of it. The system is vulnerable.

The GPS service is provided by the United States government. They can selectively degrade the service at any time and deny access to the system as and when it so chooses. This was well documented in the case of the Indian military in 1999 whilst fighting in the Kashmir region during the Kargil conflict. Periodically, the GPS signals in selected areas are degraded for a short time, but advance notice is usually provided. This is when an interruption is controlled. There are many occasions where interference comes from unwelcome sources.

GPS interference occurs frequently in locations like Chinese waters, the Black Sea and the eastern Mediterranean. The blame for such incidents has been laid at the doors of the Russian and Chinese governments. Whilst the interference may have been without the intention of harm, and probably as tests and demonstrations of their own system’s capabilities, if international tensions were to rise dramatically, it should be assumed that GPS interference will become more widespread. 

The system can be relatively easily ‘jammed’ and the effects are dramatic. A decade ago, a ‘friendly’ test was conducted aboard the Trinity House vessel ‘Galatea’. Using a jammer, with less than a thousandth of the power of a mobile phone, effectively forced false positions to be displayed on electronic charts and relayed the false information through the automatic identification system (AIS) to nearby shipping. The distress and safety system and helicopter deck stabilisation failed, clocks could no longer provide the accurate time and the ship’s radar and gyrocompass became useless.

In addition to ‘jamming’, there’s also ‘spoofing’. This involves sending false signals to one or several receivers, thus tricking ships into following bogus track lines if it relies wholly on its GPS receiver. As so many vessels place excessive reliance on their use of GPS and electronic navigation equipment, this creates a very clear danger. Worryingly, the technology to spoof the GPS signals is not difficult to obtain.

The above highlights the need for a backup system that can stand in for GPS, when the GPS signal is unavailable or unreliable, and continual development of a system pioneered over 50 years ago.

Something must be done soon, before the entire positioning, navigation, and timing system on which the modern world relies becomes further unreliable.  Failure, or unavailability of GPS without a reliable alternative, is a super-high consequence problem.

It remains an official policy of the United States Government to fully develop and implement an accurate back-up system, but funding and urgency for such action has lagged. Let us hope the new occupant of The White House will spend less time on the golf course and more attention on such matters of national and international security.

We can, of course, take matters into our own hands and be aware of the frailty of the system whilst we are out at sea. We all press the ‘ok’ button on the chart plotters to proceed beyond the disclaimer that the equipment we are about to rely on is a secondary aid to navigation, but perhaps we should all just brush up on our paper chart skills of traditional navigation?

Anacronyms and alternatives

GNSS: Global navigation satellite system, the general term describing any satellite constellation that provides positioning, navigation, and timing services on a global or regional basis.

PNT: positioning, navigation and timing.

While GPS, Global Positioning System, is the most prevalent GNSS, other nations are seeking independence and preparing, or have launched, their own, alternative, systems to provide complementary, independent PNT capability. The main ones are Russia’s GLONASS, China’s BeiDou (roughly translates as ‘the big dipper’), India’s IRNSS and Japan’s QZSS alongside the European Union’s collaboration on GALILEO.

Brexit and the billions

The Galileo system is a joint investment of all European nations, including the United Kingdom. It was announced earlier this year that the UK will not use Galileo for defence or critical national infrastructure, and that, through its new independence from the EU, it will no longer play any part in the development of Galileo or European Geostationary Navigation Overlay programmes. So, whilst attempting to avoid a political slant I do find it a dreadful waste of the reported £5 billion invested, to walk away from a united project in the skies. Brexit has a lot to answer for.

Linda Revill
Independent Writer