Current P- and T-notices

Sweden. not area bound. Reports of disturbances in satellite positioning systems.

Time: Unil further notice

Vessels in the Baltic Sea area has reported recurring disruptions in satellite positioning systems, GNSS. This applies to GPS, for example.

The Swedish Maritime Administration advices mariners who navigate with electronic chart systems to be aware that the interference can cause several different problems.

For example can the vessel appear to be in the wrong position. The positional error may be small, but can have major consequences when navigating in narrow waters.

Other vessels may display incorrect AIS transponder information. Incorrect AIS information may create the illusion of being on a collision course with other vessels, or otherwise mislead a navigator about the vessel's current situation.

The GNSS-disruptions can occur for both short and long periods of time. The disruptions can be difficult to detect.

The Swedish Maritime Administration recommends that you always have at least two independent ways of determining the vessels position. This to ensure that the vessel keeps safe distance from shallow areas. It is important not to rely solely on the position indication of the navigation system. For example, passing distance using radar can be used. Visual position determination using landmarks and compass heading can also be used.

Navigation in unknown waters should be done in fairways. In fairways, navigation is assisted with aids to navigation. Paper charts should always be on board.

When navigating at night, sector lights from lighthouses should be used if possible.