Britain’s Maritime and Coastguard Agency (MCA) has urged shipowners and seafarers to prepare for operating without dependable GPS and other satellite-derived navigation services as jamming and spoofing become more widespread.
In Marine Guidance Note MGN 719, the MCA said interference affecting global navigation satellite system (GNSS) signals has been reported across the Baltic, Black Sea, Middle East Gulf and parts of East Asia. The agency warned that positioning, navigation and timing information derived from satellites can no longer be assumed reliable in all operational areas.
The risks extend beyond a vessel’s electronic chart display and information system. The guidance identifies a range of shipboard equipment that may be vulnerable where satellite signals are disrupted or manipulated, including ECDIS, AIS, autopilots, dynamic positioning systems, radar, gyrocompasses and GMDSS communications equipment.
Operational context
The MCA also highlighted potential shore-side exposure. Vessel traffic services, pilotage systems, port management platforms and automated logistics systems may be affected where they depend on GNSS-based timing or positioning data.
Operators are advised to establish which onboard systems rely on satellite-derived information and to introduce procedures for identifying interference. The notice also calls for crews to practise alternative methods of navigation regularly, including radar fixing, visual bearings, celestial navigation and dead reckoning.
The agency’s warning follows a rise in reports of GNSS disruption affecting commercial shipping. Windward data cited in the source showed an average of 5,131 GPS jamming incidents per day during the third quarter, affecting more than 124,000 individual vessels. Separately, research by the Royal Institute of Navigation found that 14% of respondents to a survey had experienced an unsafe or unlawful situation linked to GNSS interference.
Recent cases have illustrated the operational implications of spoofed data. Four tankers in the Black Sea were reported to have broadcast positions indicating they were in Lima, Peru, more than 12,000 km from their actual operating region. Monitoring in the Gulf of Oman also identified 1,702 impossible position jumps involving 379 vessels during one week in September.
The MCA cited earlier UK government research estimating that a seven-day GNSS outage could cost the British maritime economy £1.5bn, including £1.3bn related to port operations.
The UK is developing an enhanced Loran, or eLoran, network as a terrestrial backup for satellite navigation. However, the guidance notes that alternatives will take time to become broadly available. The planned network is expected to provide an initial timing capability in 2028, while full positioning and navigation services are targeted for 2030.
Until such alternatives are established, the MCA’s message is that navigational resilience will depend on operators understanding satellite dependencies and ensuring crews retain practical skills for navigating when GNSS services cannot be trusted.