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By ALAN SORUM
Council project manager

In 2006, the council acquired a vessel location monitoring technology known as Automatic Identification System that enabled the council to monitor tanker traffic in Prince William Sound. Recently the council expanded coverage to access the system's data for the waters of Cook Inlet.

Image: Screenshot of the Automatic Identification System showing Prince William Sound and Cook Inlet.

Some tanker traffic moves from the Sound to terminals in Cook Inlet, namely the vessels operated by Tesoro. They often come in and out of the Sound carrying loads that can include diesel fuel, crude oil and jet fuel. Council staff is now able to monitor the activity of equipped vessels in all of South-central Alaska.

This vessel tracking system has transponders that receive and transmit vessel navigation information about marine vessels that is shown on electronic charts or radar displays. Each vessel equipped with the system and within range of its receiver broadcasts its name, position, speed over ground, course, radio call sign, rate of turn and other data to the transponders. This technology was previously only available to the Coast Guard's Vessel Traffic Service facilities, but now operators of any vessel equipped with this system can access the information at the press of a button.

The type of signals used by this system can only transmit in a straight line and can't curve to match the earth's surface or obstructions like mountains. This limits the useful range of the system to less than 50 miles. One strategy used to circumvent this shortcoming has been employed by the Marine Exchange of Alaska. They installed receivers at key high points across Alaska and relay the data received via the Internet to their office in Juneau.

The Marine Exchange broadcasts a feed of this navigational data to the Internet, making this available to organizations like the council, shippers and Coast Guard. Through this system, the council has been able to track tankers and other equipped vessels in Prince William Sound for several years.

Large monitors displaying navigational charts with the system's data are installed in the public areas of council offices in Anchorage and Valdez. Take some time during your next visit to see this safety technology in use.

The Automatic Identification System marks an excellent step forward helping vessels avoid collisions at sea.