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The LORAN-C transmitter Port Clarence was a transmission facility for LORAN-C situated at Port Clarence, Alaska at 65°14′40″N 166°53′12″W. It used as aerial a 411.48m high guyed mast, which was built in 1961 and which was the tallest construction of Alaska until its demolition with explosives on April 28, 2010.
LORAN (LOng RAnge Navigation is a terrestrial radio navigation system using low frequency radio transmitters in multiple deployment (multilateration) to determine the location and speed of the receiver.
The most recent version of LORAN in use is LORAN-C, which operates in the low frequency portion of the electromagnetic spectrum from 90 to 110 Kilohertz. Many nations have used the system, including the United States, Japan, and several European countries. Russia uses a nearly identical system in the same frequency range, called CHAYKA.
LORAN use has been in steep decline, with the satellite based Global Positioning System (GPS) being the primary replacement. However, there have been attempts to enhance and re-popularize LORAN, mainly to serve as a backup and land-based alternative to GPS and other Global navigation satellite system (GNSS) systems.
The current LORAN system has been phased out in the United States and Canada. The United States Coast Guard (USCG) and Canadian Coast Guard (CCG) ceased transmitting LORAN-C (and joint CHAYKA) signals in 2010