A new prompt to test the mission plan
Modern maritime operations depend heavily on Global Navigation Satellite Systems. A position generated by GPS, Galileo, GLONASS or BeiDou may feed not only a vessel's chart display, but also its AIS, route monitoring, autopilot, survey equipment, fleet-management platform and shore-based operating picture.
That dependence becomes particularly important for an uncrewed surface vessel. The remote operations centre may be many miles from the vessel and reliant on data feeds to understand what is happening at sea.
On 1 October 2026, the Maritime and Coastguard Agency published MGN 719: Operating in GNSS Denied and Degraded Environments. It highlights increasing reports of GNSS interference and encourages maritime stakeholders to examine their dependencies, contingency arrangements and ability to continue operating safely when satellite-derived position, navigation and timing information becomes unreliable.
The guidance is not a new USV certification requirement. It is, however, a useful prompt for operators, clients and support providers to test whether their mission plans remain credible when a normally dependable position source cannot be trusted.
A valid-looking position may still be wrong
Jamming blocks or degrades the satellite signal and may cause a receiver to lose its position. Spoofing presents false information that may still appear plausible to the vessel or operator.
An obvious loss of position can trigger alarms. A convincing but incorrect position may be harder to identify.
The MCA's guidance on electronic navigational aids warns that incorrect GNSS information can pass into charts, radar or automatic track-control systems with very little indication to somebody relying on a single receiver. It stresses the importance of checking position by other, genuinely independent means.
For a USV, the same principle should be considered across both the vessel and the remote operations centre. Two different displays do not provide independent verification if both ultimately receive data from the same antenna, receiver or processing chain.
The effect can extend beyond navigation
MGN 719 identifies a wide range of potentially affected systems. These include electronic charting, AIS, radar using GNSS inputs, track control, autopilots, dynamic positioning, route monitoring, communications, port systems, fleet tracking and survey-grade GNSS or RTK equipment.
For survey and inspection missions, degraded positioning may also affect the confidence that can be placed in the location associated with collected data. That does not automatically make every data product unusable, but the operator and client should understand how positioning integrity is checked, recorded and reported.
International concern is also increasing. In March 2025, the IMO, ICAO and ITU reported growing incidents of satellite-navigation jamming and spoofing and called for stronger resilience, conventional contingency infrastructure and better interference reporting.
- Electronic charts, route monitoring and automatic track control.
- AIS, radar inputs, fleet tracking and the remote operating picture.
- Dynamic positioning, timing-dependent communications and port systems.
- Survey-grade positioning, RTK corrections and the location attached to collected data.
Turn resilience into mission decisions
A technical fall-back is only useful when the people running the operation know what it means for the mission. Before departure, the operator should be able to answer five practical questions.
Detection: which indications, alarms and independent observations could reveal a problem? Depending on the vessel and operating area, these may include radar ranges or bearings, visual information, inertial sensors, dead reckoning, comparison between independent receivers or discrepancies between vessel and shore information.
Safe degraded state: what is the vessel intended to do when position confidence falls below an acceptable level? The response may involve reducing speed, leaving automatic track control, adopting an approved degraded mode, returning by an independently verified method or aborting the mission. The correct action must follow the vessel's capabilities, risk assessment and operating environment.
Authority: who can declare the position unreliable, suspend the task, change operating mode and activate recovery support? The remote operator, vessel master where applicable, client representative and supporting personnel should not have to resolve decision ownership for the first time during an incident.
Physical recovery: which recovery locations, towing or lifting arrangements, connection points and support-craft capabilities have been identified? The plan should also consider the time needed to mobilise suitable support.
Communications: how will the remote operations centre, client, support vessel, harbour authority, VTS and emergency services communicate where relevant, particularly if a timing or tracking service also depends on GNSS?
Exercise the recovery chain, not only the software
MGN 719 encourages stakeholders to exercise contingency procedures through drills and training. A useful USV scenario can begin with a discrepancy between the planned track and an independent position source, followed by loss of confidence in the primary GNSS feed.
The exercise should test transfer to the approved degraded operating mode, the decision to continue or abort, stakeholder notification, mobilisation of local marine support and the recovery, tow or safe handover of the vessel.
It should also confirm that contact information is current, support can reach the vessel within the assumed period and the recovery craft has the necessary equipment and information. Testing the complete chain may expose hidden dependencies: navigation, AIS, timestamps and a shore display may appear separate while sharing one GNSS-derived source.
A practical pre-departure checklist
The appropriate controls will depend on the vessel, mission and location. As a practical starting point, the mission team may wish to confirm that it has:
- Mapped vessel and shore systems that depend on GNSS-derived information.
- Identified genuinely independent ways to verify position.
- Defined how interference or conflicting information will be detected and recorded.
- Agreed the vessel's degraded, abort and recovery states and assigned decision authority.
- Identified safe recovery areas, suitable ports and towing or lifting arrangements.
- Established communications and escalation routes with relevant external parties.
- Checked the location, capability and mobilisation time of suitable marine support.
- Exercised the contingency and agreed how any effect on mission data will be assessed.
The wider resilience case
The consequences of GNSS disruption are not confined to one vessel. A UK government study estimated that a seven-day national outage could create £7.64 billion of economic impact across the UK. MGN 719 attributes approximately £1.5 billion of that modelled impact to maritime activity, principally port operations and shipping. These are scenario estimates rather than predictions, but they illustrate the scale of modern dependence on satellite-derived information.
The UK is developing eLORAN as a terrestrial source of resilient position, navigation and timing, with initial timing capability planned for 2028 and full position and navigation capability targeted for 2030. The MCA notes, however, that many complementary technologies will not be available at scale immediately.
Operators therefore still need practical arrangements that work with the equipment, personnel and marine resources available today.
When digital resilience becomes a marine operation
GNSS resilience is not solely an electronics problem. When a USV can no longer establish or communicate a trusted position, the response may require a remote operator, harbour authority, client and local support vessel to act as one coordinated team.
ARC's operational view is that mission planning should connect those elements before departure. The objective is not to place a crewed vessel beside every autonomous platform. It is to ensure that proportionate support, clear activation criteria and a workable recovery route exist before they are needed.
ARC can help operators identify suitable local workboats, guard vessels, pilot boats, tugs and specialist craft for planned support and time-sensitive recovery arrangements.