Mass global positioning system spoofing at ports in PRC

American Club has noted that there had been an increase of GPS spoofing incidents in and around coastal areas and ports in the People’s Republic of China (PRC) during the past year.

In July 2019 an American containership transiting the Huangpu River near the port of Shanghai experienced nearby ships appearing and disappearing from its ECDIS display. The vessel proceeded into port and later lost signals on both GPS units just before berthing.

A formal report was filed with the US Coast Guard following this incident. Following these reports the Centre for Advanced Defence Studies examined AIS data in the area. It was discovered that hundreds of ships had been spoofed and that the activity had been continuing for months, affecting ships across Shanghai simultaneously and mostly vessels navigating the Huangpu River.

Weeks’ worth of data revealed the spoofed ships’ GPS signals congregated into large circles, later dubbed “crop circles”.

The Club observed that this tactic was unlike traditional spoofing, which moves signals to the same position, thus creating a confusing traffic situation for ships’ pilots.

The Club said that it was likely that the kinds of mass disruptions as seen in the Black Sea and PRC maritime regions were occurring elsewhere, but these would have been places where the spoofing would have been difficult to detect.

An article was published in the November 2019 edition of MIT Technology Review, entitled “Ghost ships, crop circles, and soft gold: A GPS mystery in Shanghai”. It provided a summary of the kind of possible technologies likely being used and possible reasons for observing this activity in the Shanghai region.

American Club warned that GPS jamming and spoofing could create confusion in a ship’s wheelhouse, particularly when the vessel was transiting a busy port. Vessels were advised to take precautions if experiencing jamming or spoofing.

If a GPS malfunction does occur, vessel Masters were reminded to take the following measures:

  • plot the vessel’s last known position;
  • switch to the primary/secondary navigation device;
  • make a log entry detailing the time and location of the failure;
  • use all available means of navigation to navigate safely; and
  • report all failures immediately to the appropriate authorities.

For the US the USCG Navigation Centre maintains a listing of GPS status reports received, as well as instructions on how to file a report at