Switching off AIS

It is a widely known fact that some vessels switch of their AIS transponders, sometimes when within the ports, making tracking quite unreliable at times.

What is the reason for switching off the AIS and how prevalent is this practice?

The practice of switching off AIS transponders varies depending on the region, type of vessel, and the specific circumstances. In high-risk areas for piracy, it might be more common. Similarly, vessels involved in illicit activities in certain regions might frequently turn off their AIS.

  • Security Concerns: In areas with a high risk of piracy or maritime terrorism, ships might turn off their AIS to avoid detection by potential threats. This is especially common in regions known for piracy, such as the Gulf of Aden or the waters off the coast of Somalia.
  • Illegal Activities: Vessels involved in illegal activities, such as smuggling, illegal fishing, or sanctions evasion, might turn off their AIS to avoid detection by authorities.
  • Avoiding Tracking: Some vessels might not want their movements to be tracked for competitive reasons. For example, a commercial ship might not want competitors to know its routes or destinations.
  • Technical Issues: Sometimes, the AIS might be turned off due to technical problems or maintenance. It’s also possible that the system might malfunction or experience a power failure.
  • Port and Harbor Operations: In congested ports or harbors, ships might turn off their AIS to reduce the clutter on the AIS displays of other vessels. However, this is less common since port authorities usually want to track all vessels in their jurisdiction.
  • Privacy Concerns: Some private yachts or vessels might turn off their AIS for privacy reasons, especially if they don’t want their movements or locations to be publicly known.

Hi Aydin, one of the reasons comes to my mind is for commercial purposes. Maybe operator does not want to decrease the amount of port dues, as it is calculated based on time vessel spends in the port