In the Black Sea, anomalies were recently recorded that led to the failure of GPS. Difficulties with navigation experienced more than 20 ships. The US Maritime Administration registered an incident in the Black Sea (44-15.7N, 037-32.9E on June 22, 2017 at 0710 GMT).
The sailors reported to the US Coast Guard’s navigational center:
With the approach to the shoreline of Novorossiysk, GPS equipment began to receive a GPS signal with interruptions. The error in determining the coordinates within 100 meters, but the actual location was more than 25 nautical miles (about 46 km).
The GPS equipment was in order. When communicating with neighboring ships, the same problems with navigation were confirmed. That signal was determined correctly, then gave a position on land, which in principle could not be.
At the request of the vessel, the US Maritime Administration replied that the accuracy of the GPS should be about 4 meters. No anomalies associated with weather or space phenomena in that region were recorded.
Navigation experts named these anomalies as professional GPS spoofing. The bottom line is that someone is trying to fool the GPS receiver, giving it a more powerful signal than the GPS received from satellites. They claim that the transmitter sending false data was at a depth of 39 meters underwater, that the signal power of all satellites that uses GPS is the same, and that the WER or Word Error Rate (probability of error in the code combination) is 97 Percent (at a rate of less than 10 percent).
By simulating satellite signals, it is possible to send incorrect coordinates and knock the ship off the intended course. They also argue that Russia has advanced capabilities to block the work of GPS. But at the moment the exact cause of the anomaly has not been established.