AIS text messaging Marine Safety Alert

By Brian at May 31, 2010 07:05
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The Coast Guard posted a Marine Safety Alert (.pdf) on AIS text messaging that Jorge Arroyo mentioned during his presentation at the RTCM Annual Meeting a couple of weeks ago (noted in this post). The alert covers three areas of AIS use by vessels:

  • Navigation -  while AIS can serve as a valuable situational awareness tool to aid in collision avoidance, the "use of AIS text messaging does not relieve the vessel of other requirements, such as the Vessel Bridge-to-Bridge Radiotelephone regulations or of the requirements to sound whistle signals and display lights or shapes in accordance with the International or Inland Navigation Rules."
  • Emergencies - the alert warns against the use of AIS text messages for distress communications, particularly as a substitute for communications via GMDSS equipment.
  • Proper operation - the alert notes that "AIS is only as good as the information provided and exchanged, therefore, users must ensure their unit is always in effective operating condition and broadcasting accurate information" and reminds operators of their obligation to keep dynamic, static and voyage-related AIS data up-to-date.  It provides a link (.pdf) to a guide on shipboard AIS data entry.

There have been stories floating around that AIS has been improperly used in the manner cautioned against in the alert, including at least one investigation (.pdf;  see p. 28) that mentions vessels attempting to contact each other via AIS rather than by radiotelephone resulting in a collision - the so-called "AIS-assisted collision" that has been speculated about since the introduction of AIS.

The use of AIS in emergencies touches on the contentious issue of a navigation system being used for distress purposes - something that we'll likely see more about, as AIS SARTS, AIS equipped EPIRBS and other distress equipment is integrated with AIS.

The complaint heard most often about AIS is thet you can't trust it - we've all heard stories of incorrect vessel names, MMSIs and other data, as well as vessels apparently sailing "sideways" due to improper entry of dimensions or incorrect heading input devices.  This alert is a welcome reminder about these problems and hopefully will help mariners comply with the requirement for proper operation of AIS equipment.