LoNG RAnge Navigation (LORAN) is a radio navigational system for guiding ships and aircraft. Pairs of transmitters emit signal pulses that are picked up by an aircraft or ship's receiver. By measuring the difference in time between the signals reaching the receiver, the vessel's position can be plotted. The transmitters are about 970 kilometers (600 miles) apart. The range of the system is 1,800–4,500 kilometers (1,100–2,800 miles).

 

In recent decades, 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 satellite navigation 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.