What are advantages / limitations of AIS?

Advantages of AIS
  • The system is fully automated with absolutely no human intervention.
  • Unlike Radar, It is not affected by rains or Sea.
  • Its propagation is better than that of radar, due to the longer wavelength.
  • It’s possible to “see” around bends and behind islands if the land masses are not too high.
  • Additional safety at night time.
Limitations of AIS
  • The system coverage range is similar to other VHF digital applications which depends upon the height of the antenna. Typical Range 20 NM.
  • With the help of repeater stations, the range can be increased.
  • Some vessels like fishing vessels leisure craft and vessels below 500 GRT may not be fitted with AIS.
  • Accuracy of the info received is only as accurate as what is entered in the static/voyage or safety messages data.
  • The OOW should always be aware that AIS fitted on other ships under certain circumstances, can be switched off on the master’s professional judgment.


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