LORAN-C and its Application to Aviation

Examines the history and the future of a medium frequency radio naviation system known as the LORAN-C.

The paper explores Loran, acronym for LOng RAnge Navigation, that is a radio-navigation system that served Army Air Corps navigators crossing the Atlantic and Pacific Oceans. The paper examines the history, implementation, governance, and future of Loran-C with special focus on its application to avionics. The paper discusses how Loran-C has been challenged by the satellite-based Global Positioning System (GPS) but concludes that while the government has indicated that it might like to shorten its commitment to support the Loran program, it will still be around well into the 21st century.
“The need for an advanced navigation system developed from the great difficulties that the U.S. Navy experienced during world war two in the Pacific. Navigation was very difficult. The first system, Loran-A, was implemented in a small cluster of three stations in 1945. It was found to be only really effective during daylight and only over relatively short distances. Therefore, wherever a station was placed, it was not part of an effective or seamless web; there were many places throughout the Pacific where our ships could not receive the signals. The next set of stations were supported by balloon-lifted aerial antennae and utilized a lower-frequency signal and shorter pulses of information which proved to be more accurate. The experiments toward increasing accuracy and distance were discontinued and what had been labeled LF Loran was scrapped after the war was over. MIT had been originally responsible for the experimentation with Loran and also shut down its labs. Later that year, still in 1945, the US Air Force, a newly formed military wing that took the Army and Navy air squadrons, took the old Loran broadcast stations and receiver sets and installed them in Alaska to assist in navigation in the vast arctic region. Within a year, the Air Force had discovered significant information that revealed that with even lower frequencies, and greater station density, a seamless blanket of signals that could carry multiple frequencies that could provide for civilian and military use of the same stations. These stations utilized a signal technology called Cytac.”