Recently, the Maritime Administration (MARAD) issued a navigation warning that it will be in the eastern Mediterranean waters between March 18-22 this year (32-24.0N, 029-29.9E, almost in the north of Egypt. Not far away. A series of accidents at sea have occurred.
Although the specifics of these accidents have not yet been confirmed, MARAD said that the essence of the accident is that the GPS signal was interfered. At the same time, Egypt also reported a number of interference incidents with GPS signals, including misplaced or non-displayed locations. 90 deg. elbow
Do not know if you still remember, in July last year, MARAD also issued a navigation warning, pointed out that in the Black Sea, the GPS of about 20 ships encountered a strange prank "interference", resulting in the display of the ship's position is not Quasi, lost ship position, etc.
One of the most serious ones caused a serious shift in the positioning of a ship. It was simply positioned on land, and it was close to 25 nautical miles from the actual ship's position. slip-on flange
MARAD suggested that if GPS signals are found during navigation, please report them to the USCG's Navigation Safety Center (NAVCEN) in a timely manner. At the same time, NAVCEN recommends not relying too much on electronic equipment. The position of the vessel should be determined through various methods at any time.
In addition, in a series of GPS signal interference incidents last year, one of the captains' measures was approved by NAVCEN. Here's what to share with you:
After discovering the loss of its own GPS signal, the captain used the radar to mark the position and distance of the relevant coastline-related area on the paper chart. At the same time, the electronic chart (ECDIS) is switched to the Dead Reckoning mode, and the radar signal is superimposed to confirm the position of the ship.
As the ship was waiting to drift outside the port area at the time, the captain regularly entered an offset on the ECDIS to match the radar coverage. At the same time, he constantly compares paper charts with ECDIS as another verification method. welding overlay flange
The captain indicated that he had also attempted to use the depth sounder to measure the depth of water to check the position. However, at that time, the water depth in the sea area was too deep and the depth sounder could not be used. However, he believed that if the water depth was appropriate, there would be no problem using the depth sounder. butt welding cap
When the ship returned to the pilot station after returning from drifting to driving status, the captain used the Parallel Indexing method on both radars. The master thinks that using the PI method when approaching a coast or a fairway is an effective and accurate method of determining the position, offset, and turning point.
Finally, the captain reported that although the ship did not have any satellite positioning system available at the time, the above method worked well in dealing with this situation.