Hours-long GNSS interference reported in Strait of Hormuz

UK Maritime Trade Operations (UKMTO) has issued an advisory on electronic interference in the Strait of Hormuz area.

The UKMTO report dated May 18, 2025 claims that the GNSS interference lasted several hours and affected the navigation-related systems of vessels operating in the strait at the time.

Combined Maritime Forces' Joint Maritime Information Center (JMIC) has received reports from vessels in the area experiencing interference affecting navigational systems drawing positional data from multiple GNSS such as ECDIS, ARPA, AIS, and GMDSS stations.

GNSS interference is being reported at higher than normal levels from both the Red Sea area and Strait of Hormuz. JMIC has assessed that there are no linkages between GNSS interference in these two areas and will continue to monitor the situation.

JMIC said commercial shipping may be affected by GNSS interference. Whatever its origin, it is more likely to occur in military operating areas, exercise areas and in self-defence; however, spoofing also remains a concern.

JMIC highly encourages all vessels transiting the Red Sea and Strait of Hormuz to continue vigilant watchstanding to include recognising GNSS interference.

It is also recommended not to rely entirely on electronic navigation methods or autopilot when transiting through areas prone to GNSS interference and it would be prudent for mariners to consider using traditional non electronic means of position fixing to crosscheck the vessels position when in coastal or congested waters.

Crews of vessels operating anywhere within the UKMTO voluntary reporting area that experience disruptions to electronic navigation systems such as GNSS, AIS, or other positioning, navigation and timing systems are strongly encouraged to note the location and time of the disruption and take photos or video if their ships' electronics or navigation system (if impacted), and report to UKMTO as soon as practicable.