14 October 2026 | Maritime News, Navigation & Safety
The Maritime and Coastguard Agency (MCA) has issued new guidance urging the maritime industry to
prepare for a future in which GPS and other satellite navigation systems may not always be available
or reliable. With incidents of satellite interference increasing worldwide, the message is clear: modern
mariners must retain the knowledge and practical skills to navigate safely without relying entirely on
electronic positioning systems.
For decades, GPS has transformed maritime navigation. From recreational yachts and commercial workboats to the
world’s largest merchant vessels, satellite-based positioning has become an integral part of everyday operations.
But what happens when that technology fails?
In its latest guidance, MGN 719 (M+F) – Operating in GNSS Denied and Degraded Environments, published on 1
October 2026, the MCA highlights the growing risks associated with satellite navigation interference and encourages
maritime operators to strengthen their contingency arrangements.
The guidance represents an important reminder that technology, however advanced, should never replace
fundamental navigational competence.
Why Is the MCA Warning About GPS Reliability?
Global Navigation Satellite Systems (GNSS) provide the positioning, navigation and timing information upon which
much of the modern maritime industry depends.
These systems include:
ASTRONAV UK | Editorial article and developer annex 1• GPS – United States
• Galileo – European Union
• GLONASS – Russia
• BeiDou – China
Although these satellite networks have transformed navigation, they remain vulnerable to interference, disruption
and manipulation.
The MCA reports a marked increase in GNSS interference in recent years, particularly in areas such as the Baltic
Sea, Black Sea, Gulf region and parts of East Asia.
Two of the principal concerns are GPS jamming and GPS spoofing.
GPS Jamming
Jamming occurs when interference prevents a satellite receiver from receiving or correctly processing the signals it
needs.
This can result in a loss of positioning information, degraded accuracy or interruptions to navigation systems.
GPS Spoofing
Spoofing presents a potentially more deceptive risk.
Rather than simply blocking a signal, spoofing involves transmitting misleading positioning information that can
cause navigation equipment to display an incorrect location.
A vessel may therefore appear to be following its intended route while its displayed position is inaccurate.
For mariners relying heavily on electronic charts, integrated bridge systems or automated navigation equipment, the
consequences could be serious.
It’s Not Just GPS: The Wider Maritime Impact
Satellite positioning information supports considerably more than a vessel’s chartplotter.
Modern maritime operations frequently depend on GNSS information for electronic chart systems, AIS, integrated
bridge equipment, autopilots, dynamic positioning and some communications and safety systems.
Ports, vessel traffic services and shore-based operations can also depend on satellite-derived positioning and
timing.
The financial implications of a prolonged disruption are significant.
According to figures referenced by the MCA from a 2023 UK government assessment, a seven-day GNSS outage
could result in approximately £1.5 billion in losses across the UK maritime sector, including shipping, port
operations and fishing.
However, beyond the financial consequences lies a more fundamental concern: the ability of mariners to maintain
safe navigation when familiar technology becomes unavailable or unreliable.
The Return of Traditional Navigation Skills
ASTRONAV UK | Editorial article and developer annex 2One of the most important elements of the MCA’s guidance is its emphasis on maintaining proficiency in alternative
methods of navigation.
The agency recommends that mariners practise navigating safely using information that does not depend entirely on
satellite positioning.
These methods include:
• Celestial navigation: Using observations of the Sun, Moon, stars and planets to establish a vessel’s position.
• Dead reckoning: Estimating a vessel’s position using a known starting point, course, speed and elapsed time.
• Visual navigation: Using identifiable landmarks, bearings and traditional chartwork to establish position.
• Radar navigation: Using radar ranges and bearings to obtain independent position fixes.
• Estimated positions: Accounting for factors such as tide, current and leeway when determining a vessel’s likely
position.
These are not outdated techniques. They remain valuable components of competent seamanship and effective
navigational risk management.
Importantly, the MCA is not suggesting that mariners abandon modern electronic navigation.
Instead, the message is one of resilience: navigators should understand the limitations of their equipment and be
capable of continuing safely when satellite-derived information cannot be trusted.
Why Celestial Navigation Still Matters in 2026
For generations, mariners crossed oceans using the Sun, stars, accurate timekeeping and mathematical
calculations to determine their position.
Long before GPS became commonplace, celestial navigation provided an independent method of ocean navigation.
Today, it remains particularly relevant to offshore and ocean-going sailors.
By using a sextant to measure the altitude of a celestial body above the horizon, together with an accurate time
reference and appropriate nautical publications, a navigator can calculate a line of position.
Combining suitable observations allows the navigator to establish an estimated geographical position independently
of satellite positioning.
Celestial navigation does, of course, have limitations. It requires training, practice, suitable visibility and the correct
equipment. It is not a direct substitute for every function provided by modern electronic systems.
Nevertheless, for vessels undertaking extended offshore passages, it provides an additional method of position
fixing that does not rely on receiving satellite navigation signals.
The real value lies not simply in knowing how to use a sextant, but in understanding the principles of navigation and
maintaining the confidence to apply them.
Could You Navigate Without Your Chartplotter?
Consider a relatively simple scenario.
ASTRONAV UK | Editorial article and developer annex 3 You’re undertaking an offshore passage, several hundred miles from land. Your vessel is equipped with a modern
chartplotter, AIS, autopilot and satellite-based navigation equipment.
Suddenly, your GPS position becomes unreliable.
Your electronic chart may no longer show an accurate position, and other connected systems could be affected.
Would you know how to establish your position independently?
Could you maintain a reliable dead reckoning plot?
Could you use celestial observations to support your estimated position?
Would you recognise the difference between a genuine loss of satellite signal and a potentially misleading position
caused by spoofing?
These are practical questions worth considering before an equipment failure or interference event occurs.
Navigation is not simply about knowing where you are. It is about understanding how you arrived there, where you
are heading and how to verify your position using the information available.
What Should Yacht Owners, Skippers and Maritime Operators Do?
The MCA’s guidance encourages a proportionate approach to GNSS resilience, taking account of the vessel, its
operating environment and the equipment fitted.
For yacht owners, professional skippers, commercial operators and offshore crews, there are several sensible
measures worth considering.
1. Understand your equipment. Identify which navigation and safety systems depend on satellite-derived
positioning or timing.
2. Maintain independent navigation skills. Continue practising traditional chartwork, position fixing, compass
navigation and dead reckoning.
3. Review contingency procedures. Consider how you would respond to a loss of GPS or conflicting positioning
information.
4. Cross-check your position. Use independent navigational observations wherever practicable rather than relying
on a single electronic source.
5. Practise realistic scenarios. Incorporate GPS disruption into passage planning, crew training and navigation
exercises.
6. Consider celestial navigation training. For offshore and ocean-going mariners, developing competence in
celestial navigation can provide an additional layer of navigational resilience.
The objective is not to create unnecessary concern about satellite navigation, but to ensure that mariners remain
prepared for circumstances in which it cannot be relied upon.
The Future of Navigation: Technology and Traditional Seamanship Working
Together
The maritime industry is already exploring alternative positioning technologies.
ASTRONAV UK | Editorial article and developer annex 4The UK Government is developing plans for an enhanced Long-Range Navigation (eLORAN) system, intended to
provide an independent terrestrial alternative to satellite-based positioning and timing.
Other technologies under consideration include automated celestial navigation, visual position fixing, inertial
navigation systems and alternative radio-based positioning methods.
However, many of these technologies remain under development and may not be widely available in the immediate
future.
For today’s mariners, the most accessible form of resilience remains a combination of reliable equipment, sound
procedures, navigational awareness and practical competence.
Technology will undoubtedly continue to advance, but the fundamental principles of navigation remain unchanged.
AstroNav UK’s Perspective: Good Navigators Should Never Depend on One
System
At AstroNav UK, we believe that modern technology and traditional seamanship should complement one another.
Electronic navigation systems are extraordinary tools, but understanding the principles behind navigation is what
allows mariners to use those tools effectively, recognise their limitations and respond confidently when something
goes wrong.
From basic chartwork and traditional position fixing through to advanced celestial navigation, maintaining these skills
is an important part of developing capable, confident and resilient navigators.
Whether you’re a recreational sailor, an aspiring Yachtmaster, a professional skipper or an experienced mariner
preparing for ocean passages, the ability to navigate independently of satellite technology remains a valuable skill.
The MCA’s latest guidance reinforces something that experienced navigators have understood for generations:
The best navigation system is not necessarily the most advanced. It’s the one you understand, can verify
and can continue to use when circumstances change.
Final Thoughts: Are We Becoming Too Reliant on GPS?
The MCA’s warning is not a prediction that GPS will disappear, nor is it a call to abandon electronic navigation.
It is a recognition that satellite systems can be disrupted and that the maritime industry must be prepared.
As navigation technology becomes increasingly integrated and automated, maintaining independent navigational
skills becomes even more important.
Celestial navigation, traditional chartwork and dead reckoning should not be viewed merely as historical practices.
They remain practical tools that contribute to maritime safety, navigational resilience and professional seamanship.
The question every mariner should ask is simple: if your GPS stopped working tomorrow, would you still
know where you were?
Learn More About Celestial Navigation
AstroNav UK provides maritime training covering traditional navigation, celestial navigation and advanced
Yachting qualifications, including the IYT Master of Yachts Unlimited programme.
ASTRONAV UK | Editorial article and developer annex 5 For those interested in developing their knowledge of astronavigation, from introductory principles to advanced
ocean navigation, visit www.astronav.co.uk.
Official Reference
Maritime and Coastguard Agency, MGN 719 (M+F) – Operating in GNSS Denied and Degraded Environments,
published 1 October 2026.
Read the official MCA guidance
This article is provided for general information and maritime education. Mariners and operators should consult the full MCA
guidance and apply appropriate procedures for their vessel and operating environment.